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2008:132 CIV
M A S T E R ' S T H E S I S
An Energy Strategy for aResidential Scheme in London
Clas Persson
Luleå University of Technology
MSc Programmes in Engineering
Mechanical EngineeringDepartment of Applied Physics and Mechanical Engineering
Division of Energy Engineering
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I
Preface
This thesis is the work conducted by Clas Persson at Hoare Lea Consulting.
I would like to thank the following people. Phil Dow for letting me write my master thesis at
Hoare Lea Consulting. James Ford my supervisor and mentor at Hoare Lea Consulting foralways taking time to answer questions and continuously helping out with the report.
I would also like to thank my girlfriend and my family in Sweden for their support.
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II
Abstract
This thesis will investigate the option to implement onsite renewable and efficient energy
systems in an urban area in the UK. This is in order to lower the carbon dioxide emissions for
a residential scheme that is being developed at the Lots Road site in London. The energy
strategy target for the Lots Road site is to achieve a 50% reduction in carbon dioxideemissions compared to utilizing fossil fuelled energy.
Energy system studies and a Lots Road site investigation were made in order to gain
understanding of the energy generation process and where they could be placed onsite. Then
an evaluation of the energy systems carbon dioxide emissions and energy outputs were carried
out with the purpose of finding suitable systems for the Lots Road site. From the energy
system evaluation biomass, combined heat and power, solar water heating and photovoltaic
were selected as being suitable energy systems to be used at the Lots Road site.
The thesis shows that there are several options that could be implemented into the energy
strategy to achieve the 50% reduction target. The final option is to use biomass fuel for
thermal energy generation. It will be burnt in biomass boilers in two energy centres on the
Lots Road site. The biomass boilers will be utilized to deliver the major part of the sites
thermal demand. It will be used together with on site roof based solar water heating panels.
The panels will help to deliver thermal energy for the site. Roof based photovoltaic (PV)
panels will also be put in place to deliver electricity and will together with green roofs be used
as sustainable design features. The final option will achieve a carbon dioxide reduction of
54.5%.
The use of biomass boilers, solar water heating and photovoltaic panels at the Lots Road site
are the most suitable energy strategy options. This is because the selected renewable energies
reduce the sites carbon dioxide emissions and are available on sites across the UK.
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III
Table of Content
Preface ................................................................................................................................... I Abstract ................................................................................................................................. II Table of Content ................................................................................................................... III 1. INTRODUCTION ..............................................................................................................1
1.1 Current situation ...........................................................................................................1 1.2 Project Objectives .........................................................................................................2
2. Methodology and Problem description ................................................................................3 3. THE LOTS ROAD SITE ....................................................................................................5
3.1 The Site ........................................................................................................................6 3.2 Overview North and South side .................................................................................7 3.3 Rule of Thumb ..........................................................................................................8 3.4 Energy demand and emissions ..................................................................................9 3.4.1 Energy demand ......................................................................................................9 3.4.2 Carbon dioxide emissions.......................................................................................9
4. Energy systems ................................................................................................................. 10 4.1 Biomass ...................................................................................................................... 11
4.1.1 Carbon efficiency ................................................................................................. 11 4.1.2 Urban placement .................................................................................................. 11 4.1.3 Planning permission ............................................................................................. 11 4.1.4 Availability .......................................................................................................... 12 4.1.5 Cost ..................................................................................................................... 12
4.2 Biomass Combined Heat and Power (CHP) ................................................................ 13 4.2.1 Carbon efficiency ................................................................................................. 13 4.2.2 Urban placement .................................................................................................. 13 4.2.3 Planning permission ............................................................................................. 13 4.2.4. Availability ......................................................................................................... 14 4.2.5 Cost ..................................................................................................................... 14
4.3 Combined Heat and Power (CHP) ............................................................................... 15
4.3.1 Carbon efficiency ................................................................................................. 15 4.3.2 Urban placement .................................................................................................. 15 4.3.3 Planning permission ............................................................................................. 15 4.3.4 Availability .......................................................................................................... 16 4.3.5 Cost ..................................................................................................................... 16
4.4 Ground Source Heating (GSH) ................................................................................... 17 4.4.1 Carbon efficiency ................................................................................................. 17 4.4.2 Urban placement .................................................................................................. 17 4.4.3 Planning permission ............................................................................................. 17 4.4.4 Availability .......................................................................................................... 18 4.4.5. Cost .................................................................................................................... 18 4.5 Photovoltaic (PV) ....................................................................................................... 19 4.5.1 Carbon efficiency ................................................................................................. 19 4.5.2 Urban placement .................................................................................................. 19 4.5.3 Planning permission ............................................................................................. 20 4.5.4 Availability .......................................................................................................... 20 4.5.5 Cost ..................................................................................................................... 20
4.6 Solar Water Heating (SWH)........................................................................................ 21 4.6.1 Carbon efficiency ................................................................................................. 21
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4.6.2 Urban placement .................................................................................................. 21 4.6.3 Planning permission ............................................................................................. 21 4.6.4 Availability .......................................................................................................... 22 4.6.5 Cost ..................................................................................................................... 22
4.7 Wind power ................................................................................................................ 23 4.7.1 Carbon efficiency ................................................................................................. 23 4.7.2 Urban placement .................................................................................................. 23 4.7.3 Planning permission ............................................................................................. 23 4.7.4 Availability .......................................................................................................... 24 4.7.5 Cost ..................................................................................................................... 24
5 Evaluations and system selections .................................................................................. 25 5.1 Evaluation Matrixes .................................................................................................... 26 5.2 Energy system evaluation ................................................. .......................................... 29
5.2.1 Wind power ......................................................................................................... 29 5.2.2 Biomass ............................................................................................................... 30 5.2.3 Combined Heat and Power ................................................................................... 31 5.2.4 Biomass CHP ....................................................................................................... 32 5.2.5 Solar Water Heating ............................................................................................. 33 5.2.6 Photovoltaic ......................................................................................................... 34 5.2.7 Ground Source Heating ........................................................................................ 35
5.3 Energy system selection .............................................................................................. 36 5.3.1 Discussion ......................................................................................... ................... 36
5.4 Energy centre .............................................................................................................. 37 5.4.1 Energy system evaluation for an energy centre. .......... .......................................... 37 5.5 Sustainable design systems .................... ................................................................. 38 5.5.1 Selection of sustainable design systems ................................................................ 38
5.6 Site evaluation ............................................................................................................ 39 5.6.1.1 Direction ........................................................................................ ................... 39 5.6.1.2 Architectural Drawings Block JJ ....................................................................... 40 5.6.2 Block HH ............................................................................................................. 41 5.6.2.1 Direction ........................................................................................ ................... 42 5.6.2.2 Architectural Drawings Block HH .................................................. ................... 42 5.6.3 Block GG ............................................................................................................. 44 5.6.3.2 Architectural Drawings Block GG .................................................. ................... 45 5.6.4 Block FF .............................................................................................................. 46 5.6.4.2 Architectural Drawings Block FF ...................................................................... 47 5.6.5 Block AA to EE ................................................................................................... 49 5.6.5.2 Architectural Drawings Block EE ...................................................................... 50 5.6.5.4 Architectural Drawings Block DD .................................................. ................... 52 5.6.5.6 Architectural Drawings Block CC .................................................. ................... 54 5.6.5.8 Architectural Drawings Block BB .................................................. ................... 56 5.6.5.10 Architectural Drawings Block AA ................................................................... 58
6 Energy Strategy ............................................................................................................. 60 6.1 Lots Road Energy demand .......................................................................................... 60 6.2 Energy Strategy Option A ........................................................................................... 61
6.2.1 Evaluation Option A .................................................. .......................................... 62 6.2.2 Advantages and Disadvantages of Option A ......................................................... 63 6.2.4 Option A energy distribution ................................................................................ 65 6.2.5 Decision ........................................ ....................................................................... 66
6.3 Reviewing Option A ................................................................................................... 67
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6.4 Option B ..................................................................................................................... 68 6.4.1 The final recommendation .................................................................................... 68 6.4.2 Biomass ............................................................................................................... 69 6.4.3 Solar water heating............................................................................................... 70 6.4.4 Control of delivered thermal energy .................................................. ................... 70 6.4.5 Photovoltaic ......................................................................................................... 71 6.4.6 Control of delivered electrical energy ................................................................... 71 6.4.7 Backup ................................................................................................................. 72 6.4.8 Target 50 % CO2 reduction ................................................................................... 73 6.4.9 Placement of energy systems on the Lots Road site .............................................. 74
7 Schematics and Drawings .............................................................................................. 77 7.1 Legend Explanation ................................................................................................ 80 7.2 Schematics Explanation .......................................................................................... 81 7.2.1 Solar water heating............................................................................................... 81 7.2.2 Biomass and gas boilers ....................................................................................... 82
7.3 Drawings .................................................................................................................... 83 7.3.1 Explanation of electrical distribution .................................................................... 83 7.3.2 Explanation of thermal distribution ...................................................................... 84 7.3.3 Explanation of residential unit connection ............................................................ 85
9 Discussion ......................................................................................................................... 86 10 Conclusion ...................................................................................................................... 88
List of Figures .................................................................................................................. 89 List of Tables. ............................................................................................................... 90
References ........................................................................................................................ 91 Appendix A1-A1.7 & A2-A2.2: Energy Systems & Sustainable Design Systems………..…93
Appendix B1-B10.7: Calculations & Technical Data…………………………………...…..165
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1. INTRODUCTION
1.1 Current situation
When earth absorbs the energy delivered from the sun it emits thermal energy and this is what
heats the atmosphere. Carbon dioxide is a greenhouse gas and it helps to keep the earth’ssurface warm because it traps thermal energy, similar to a greenhouse, trying to leave the
atmosphere. Greenhouse gases in the atmosphere are increasing and one reason to the increase
are the carbon dioxide emissions from burning fossil fuel. [1]
Increase of greenhouse gas to the atmosphere will raise the temperature in the atmosphere and
will therefore add to global warming. This can disturb earth’s eco system and is a global
problem. [2]
The UK is now trying to decrease its emission of carbon dioxide into the atmosphere. One
major part of carbon dioxide emissions in the UK are from fossil fuelled energy providing
heat and electricity to buildings. Buildings are responsible for 50 % of the carbon dioxide
emissions in the UK. [3] In order to decrease emissions the building regulation target are set
to a 20% carbon dioxide reduction from 2002 standards for new dwelling developments.[4]
New developments in London also have guidelines from the London planning toolkit and
from the Mayor of London’s energy strategy. This is to make London more energy efficient
and to lower London’s carbon dioxide emissions. London’s energy consumption is currently
higher then Irelands. [5]
The Lots Road site is a residential scheme being developed in London and has approximately
700 residential flats. The energy strategy will provide heat and electricity to the residents with
significant reduction in carbon dioxide emissions compared to fossil fuelled energy. This will
decrease the greenhouse gas released into the atmosphere.
One alternative to achieve this is by renewable energies. Renewable energies do not add to the
increase of greenhouse gas to the atmosphere. There are several different types of renewable
energies such as photovoltaic, biomass and wind power. Another alternative to increase
energy efficiency and decrease emissions is to use combined heat and power (CHP). Natural
gas fired CHP will provide carbon dioxide emission savings and increase energy efficiency.
Renewable energy fuelled CHP exists but is still a relatively new technology in the UK.
As mentioned there are several energy systems to choose from but unfortunately urban areas
such as the Lots Road site are limited with renewable energy resources, for example the
amount of sunlight and wind speed available. This reduces the possibility to harvest
renewable energy onsite.
The task for this thesis is to recommend an energy strategy so the Lots Road site will have
low carbon dioxide emissions by utilizing a feasible substitute to fossil fuelled energy.
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1.2 Project Objectives
To recommend an energy strategy for the Lots Road site that has significant reduction in
carbon dioxide emissions. Compared to if the Lots Road site were powered and heated with
fossil fuelled energy.
The primary objective is achieved:
• When there is reduction in carbon dioxide emissions of 50%, compared to fossil
fuelled energy generation.
• When the energy systems selected for the Lots Road site are well known technologies
implemented in urban areas across the UK.
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2. Methodology and Problem description
The problem for this thesis is to design an energy strategy for the Lots Road site.
The energy strategy should have significant reduction in carbon dioxide emissions. Compared
to if the Lots Road site were powered and heated with fossil fuelled energy.
The Methodology to achieve this is to calculate the energy demand for the Lots Road site by
using rule of thumbs. When the energy demand is determined the carbon dioxide emissions
for the site can be calculated to establish the carbon dioxide reduction needed. The project
objective is achieved at a 50% reduction.
To find the most suitable energy systems for the Lots Road site a study and analysis of energy
systems were carried out. It included several renewable energy technologies. The renewable
energy technologies studied are stated in the Energy systems section. The analysis focused on
carbon dioxide emission savings and the possibility of implementing the energy systems in
urban areas.
After the energy system study an examination of the Lots Road site was completed. The site
consists of nine blocks and the examination was accomplished by investigating each blocks
possibility for energy generation. For example, roof orientation to see if solar water heating
panels can be installed.
Evaluation and selection of energy systems suitable at the Lots Road site were then carried
out. This was to establish the most suitable energy technologies for the Lots Road site. It was
achieved by evaluating the carbon dioxide emission efficiency, energy system output,
availability and cost for the different energy systems. The outcome of the evaluation was then
the basis of the selection for energy systems suitable at the Lots Road site.
Energy strategy options for the suitable systems were then evaluated and a selection for the
Lots Road site was recommended.
In the last part of the thesis schematics and drawings are shown of the energy systems
selected for the Lots Road site. The schematics show the energy system configuration and the
drawings will show the thermal and electrical distribution to the site.
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Methodolgy Flow Diagram
Energy Demand Assessment
CO2 Emission Assessment
Energy System Studies
Site Examination
Final Recommendation
System Configuration
Figure 1 methodology flow diagram
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3. THE LOTS ROAD SITE
The Lots Road site is a residential scheme in London providing approximately 700 private
residences in total. The scheme is being designed by Sir Terry Farrell architects and is a
building site adjacent to the Thames and Chelsea Harbour. The central feature of the project is
the conversion of the decommissioned power station which is around 105 years old and willbe converted into residential flats around a central atrium/street.
For this thesis boundary conditions (BC) are set for the Lots Road site. They are for
modification of the architectural design and are guidelines for when designing the energy
strategy.
This is important for the report since there are no other restrictions to the site. The boundary
conditions will help to focus on how to provide low carbon dioxide emission energy to the
buildings.
This is instead of focusing on building design and how to lower the energy demand for the
buildings. This is for example designing buildings to prevent heat gain. This is also important
but not a focus for this report.
The Lots Road site is as shown in the architectural drawings 2001[6] and the boundary
conditions solely set for this thesis are:
Can
• Add floors to buildings.
• Determine “best” usage of all internal area.
• Add buildings over ground as long as they are not directly connected to any of the
blocks and space, on the site, is available.
• Add buildings under ground they can be connected to block or blocks as long as spaceis available.
Can Not
• Raise new buildings for residential, office or retail purpose.
• Remove any of the proposed blocks for the site.
• Add floors to blocks under ground for residential, office or retail purpose.
• Add floors to blocks over ground.
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3.1 The Site
The Lots Road site consists of nine residential blocks. The buildings are described here from
the information provided in the Lots Road 2001 stage 3 Design Report [7] and is shown from
the architectural drawings [6]
Figure 2 over view of the site
North side:
South side:
The site is divided into two sides with a creek separating the North and South side. The creek
leads out to river Thames and has two towers each side of the creek. The North side consists
of the Power Station (Block JJ), Block HH and the North tower (Block GG). The south side
consists of the South tower (Block FF) and five residential blocks with Block EE next to the
tower and Block AA located where the creek narrows.
Block JJ Block HH Block GG
Block BB Block CC
Block DD
Block AA
Block FFBlock EE
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3.2 Overview North and South side
Figure 3 showing the Lots Road south side
Figure 4 showing the Lots Road north side
Block FFBlock EEBlock DDBlock CCBlock BBBlock AA
N
W
E
S
N
W
E
S
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3.3 Rule of Thumb
In order to calculate the energy demand for the Lots Road site, rule of thumbs for the energy
demand were used for residential, office and retail areas. This was for the thermal and
electrical demand. The thermal demand provided by natural gas is for space heating and hot
water. The electrical demand provided from the electrical grid is for lighting and appliances.
The Lots Road site is mainly residential and the rule of thumbs was provided by Hoare Lea
Consulting [8]. The thermal demand was 80kWh/m2 /year and the electricity demand for a
residential flat was 40kWh/m2 /year.
To determine the yearly energy demand the total floor area are multiplied with the rule of
thumbs.
Example: The energy demand for a residential flat with an area of 100m2
would be:
100m2
x (40+80) (kWh/(m2
x year)) = 12000 kWh/year. Equation (1)
The calculation from equation 1 shows that the yearly energy demand would be 12000 kWh.
If residential flats are using comfort cooling the electricity demand was estimated to
50kWh/m2 /year. The comfort cooling rule of thumb was also provided from Hoare Lea
Consulting [8].
The energy demand for retail areas on the Lots Road site were calculated from rule of thumbs
provided by the London planning toolkit [9].The thermal demand was 65kWh/m2 /year and the
electricity demand was 234kWh/m2 /year. The high electrical demand, compared to residential
units is due to the high usage of air conditioning (AC).
For office areas the rule of thumbs was also provided from the London planning toolkit [9].
They were for the thermal demand 97kWh/m2 /year and for the electrical demand
128kWh/m2 /year.
The blocks energy demand are shown in appendix B9 on pages 187-191.
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3.4 Energy demand and emissions
3.4.1 Energy demand
The total energy demand is calculated from adding all the nine blocks energy demand on the
Lots Road site. The total energy demand calculation is shown in appendix B9 page 191. TheLots Road sites energy demand is estimated to 13000MWh/year. Heat loss factors in the
energy system when delivering energy to the buildings have not been investigated in this
report.
The thermal and electrical proportion of the total energy demand is estimated, from appendix
B9 pages 181-191, to 8500MWh/year for the thermal demand and to 4500MWh/year for the
electrical demand.
3.4.2 Carbon dioxide emissions
The carbon dioxide emissions for the Lots Road site with energy generated from fossil fuels
are calculated below. Natural gas is assumed as fuel to provide the thermal energy and with
electricity delivered from the grid. This report has not investigated the carbon dioxide
emissions that will be emitted during fuel delivery.
The gas boiler efficiency is determined to 78% and will therefore increase the thermal CO2
emissions. The efficiency data is from the notional building data in SAP 2005 [10].
Carbon dioxide conversion factors to calculate the emissions are provided from BSRIA. It is
for natural gas 0.194(CO2 kg/kWh) [11] and for electricity from the grid 0.4222(CO2 kg/kWh)[12]. The emission conversion factors are multiplied with the energy demand per year to get
the kg CO2 emitted per year.
The total carbon dioxide emissions are calculated by multiplying the conversion factors with
the thermal and the electrical demand.
(8500000(kWh/year) / 0.78) x 0.194(CO2kg/kWh) + 4500000(kWh/year) x
0.4222(CO2kg/kWh) = 4013102.564 CO2 kg/year Equation (2)
The project objective target is to achieve a 50% reduction in carbon dioxide emissions. From
Equation (2) a 50% reduction is approximately 2000 ton/year CO2.
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4. Energy systems
The following are brief descriptions of different energy systems. Each energy system has a
short system description and sections of Carbon dioxide (CO2) efficiency, Urban placement,
Planning permission, Availability and Cost. Below are brief explanations of the different
sections.
Carbon dioxide reduction is investigated for the energy systems. The carbon dioxide emission
reduction is calculated from replacing approximately 20% of the sites total energy usage with
the evaluated energy system. The reduction is shown in the Carbon dioxide section for each
system. Utilizing 20% of renewable energies on the Lots Road site is a realistic energy target
and has been chosen here only as an example to compare carbon dioxide savings for the
different energies.
The energy systems are evaluated on if they are difficult or easy to implement in an urban
area. The evaluation considers for example system physical size compared to the energy
output achieved. The evaluation is carried out in the Urban placement section.
It is important with well established and available energy systems when implementing them
onsite because it increases reliability and lowers the need for backup. The Availability section
evaluates how established the energy systems are in the UK.
In order to develop a scheme it is essential to get planning permission. The Planning
permission section investigates the possibility for an energy system to get planning
permission.
Cost is not of a high priority to this report but the capital cost is calculated for a set energy
output for all energy systems. The cost can be seen in the Cost section for each energy system
and the calculations are shown in appendix B5 on page 173. The energy output,1500MWh/year, is chosen here only for cost comparisons between the different energy
systems. The selection of 1500MWh/year is on the basis that any selected energy output per
year will have the same outcome. For example if PV has the highest capital cost for
1500MWh/year it will have the highest cost for any selected energy output per year.
The energy systems chosen, explained and evaluated here are the ones that are the most
suitable for the Lots Road site. More energy systems have been evaluated and excluded from
this section they are shown in appendix A1.7 on pages 146-150.
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4.1 Biomass
Biomass can be utilized to generate heat and are considered to be a renewable energy source.
In this thesis the carbon dioxide emissions released during combustion are the carbon dioxide
absorbed from photosynthesis so the net emission for biomass is zero.
Biomass is bio organic material that is being processed to generate thermal energy (heat).
There are solid and wet biomass fuels for example solid fuel like woodchips and willow or
wet fuel in form of methane extracted from anaerobic digestion.
Solid fuel burnt in biomass boilers are considered more viable in urban areas then using wet
fuel. This is because solid fuel does not need processing before usage and it is easier to
transport. For example, methane needs to be extracted from bio waste in anaerobic digestion
and transported in a sealed tank or via a pipeline to the site before it can be utilized as fuel.
More information is shown the biomass section in appendix A1.1 on pages 93-99.
4.1.1 Carbon efficiency
Carbon dioxide reduction is investigated for biomass when utilizing biomass for 20% of the
Lots Road sites energy demand. The 20% are chosen only for CO2 reduction comparison
between the different energy systems. The reduction in CO2 emissions is then 16.2%.
Emissions for fuel delivery to end user are not considered for the 16.2% reduction.
The CO2 reduction comparison matrix is shown in Table 2 and the CO2 emission calculations
are shown in appendix B4.1 on page 170.
4.1.2 Urban placement
An evaluation on implementing biomass in an urban area was completed.
The key points for implementing biomass are that it can deliver all of the thermal demand to a
building and that the biomass boilers favourably can be placed in the basements or in a
separate building. It will then be out of sight for the residents and will not take up space in the
residential flats. It is also that when implementing biomass in an urban area investigation
should be carried out to ensure secure fuel deliveries and sufficient fuel storage.
4.1.3 Planning permission
Investigation of the possibility for biomass to obtain planning permission on the Lots Road
site was carried out.
The key points are that biomass boilers have a small visual intrusion and it can be placed
underground or in a separate building where it is out of sight. When implementing biomass
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boilers it should be design to be as unobtrusive as possible in order to obtain planning
permission [13]. It will require an external flue that will terminate above the roof of the
building.
4.1.4 Availability
Biomass is considered available and established from the research in this thesis and there are
biomass boilers currently providing energy for buildings onsite. For example in Barnsley
council where biomass is heating over 166 flats from a 470 kW wood fuelled heating scheme.
[14]
4.1.5 Cost
The energy output of 1500MWh/year is chosen here only for cost comparison between the
energy systems. The capital cost for implementing biomass is then £ 140, 000.
The cost comparison matrix is shown in Table 3 and the cost calculations are shown in
appendix B5 on page 173.
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4.2 Biomass Combined Heat and Power (CHP)
Biomass CHP is a combined heat and power plant utilizing biomass fuel and is considered to
be a renewable energy source. The net CO2 emissions released into the atmosphere is zero.
Biomass combined heat and power uses biomass to generate thermal energy. The thermalenergy drives a generator which generates electricity and is utilized in thermal applications.
More information on biomass CHP is shown in appendix A1.2 on page 107.
4.2.1 Carbon efficiency
Carbon dioxide reduction is investigated for biomass CHP when utilizing it for 20% of the
Lots Road sites energy demand. The 20% are chosen only for CO2 reduction comparison
between the different energy systems. The reduction in CO2 emissions is then 21.1%.
Emissions for fuel delivery to end user are not considered for the 21.3% reduction. The
biomass CHP system is for this thesis considered to have a power to heat ratio of 1:1.286. [15]
The biomass CHP system will then deliver 1.286 units of heat for every unit of electricity
produced.
The CO2 reduction comparison matrix is shown in Table 2 and the CO2 emission calculations
are shown in appendix B4.2 on page 171.
4.2.2 Urban placement
From the research in this thesis it is considered unreliable to utilize biomass CHP to deliveronsite energy for a residential scheme in the UK. No biomass CHP was found, except test
plants, being used in an urban areas delivering energy onsite. It is a promising technology
working in a basement or in an energy centre. Biomass CHP could deliver heat and power to
residents but the biomass fuel supply and storage space needs to be investigated.
4.2.3 Planning permission
Considering planning permission for biomass CHP is similar to CHP. Biomass CHP would
have a small visual intrusion placed in a basement or in a separate building. The biomass CHPengine would require an external flue that would terminate above the roof of the building. The
biomass CHP system and flue should be designed to be unobtrusive in order to obtain
planning permission. [13]
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4.2.4. Availability
Biomass CHP is the only energy system that is not considered available from the research
carried out in this thesis it is however utilized on the continent in countries like Austria and
Germany [16]. From the biomass CHP investigation there are only test plants located in urban
areas [17] in the UK providing heat and power for residents.
This is why biomass CHP is considered as a new technology to provide onsite energy in urban
areas. Even though biomass CHP is starting to be utilized more it is for example decided that
it will be implemented at Heathrow airport in terminal five. [18]
4.2.5 Cost
The energy output of 1500MWh/year is chosen here only for cost comparison between the
energy systems. The capital cost for implementing biomass CHP is then £ 380, 800.
The cost comparison matrix is shown in Table 3 and the cost calculations are shown in
appendix B5 on page 173.
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4.3 Natural Gas Fired Combined Heat and Power (CHP)
Combined heat and power is for this thesis selected, from the CHP evaluation in appendix
A1.2 on pages 109-110, as a natural gas engine CHP. The CHP engine is therefore not a
renewable energy source. There are several different CHP types for example steam, gasturbines or gas engines CHP.
Gas engine CHP is chosen for this report because it has a broad output range and is an
available technology.
More information on CHP is shown in appendix A1.2 on pages 100-110.
As mentioned in the biomass CHP section, CHP delivers heat and power. The process is that
thermal energy is released from combustion and drives a generator to create electricity. The
thermal energy not converted to electricity is then utilized for thermal applications.
4.3.1 Carbon efficiency
Carbon dioxide reduction for CHP is investigated when utilizing it for 20% of the Lots Road
site energy demand. The 20% are chosen only for CO2 reduction comparison between the
different energy systems. The reduction in CO2 emissions is then 5.3%. The CHP system is
for this thesis considered to have a power to heat ratio of 1:1.286 [15]. It will then deliver
1.286 units of heat for every unit of electricity produced.
The CO2 reduction comparison matrix is shown in Table 2 and the CO2 emission calculations
are shown in appendix B4.3 on page 171.
4.3.2 Urban placement
An evaluation on implementing CHP in an urban area was completed.
The key points for implementing CHP are that it can deliver a large part of the heat and power
demand to the building. The CHP system can also favourably be placed in the basements or in
a separate building where it will be out of sight for the residents and not taking up space in the
flats.
4.3.3 Planning permission
Investigation for CHP to obtain planning permission when being implemented on the Lots
Road site was carried out.
The key points are that CHP systems have a small visual intrusion and that it can be placed
underground or in a separate building where it is out of sight. When implementing CHP it
should be design to be as unobtrusive as possible in order to obtain planning permission. [13]
It will require an external flue that will terminate above the roof of the building.
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4.3.4 Availability
CHP is considered available and established from the research in this thesis. There are CHP
systems currently working efficiently delivering heat and power onsite to residents. Forexample in Bristol in the Barton hill community scheme. [19]
4.3.5 Cost
The energy output of 1500MWh/year is chosen here only for cost comparison between the
energy systems. The capital cost for implementing CHP is then £ 180, 000.
The cost comparison matrix is shown in Table 3 and the cost calculations are shown in
appendix B5 on page 173.
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4.4 Ground Source Heating (GSH)
Ground source heating systems utilize the grounds natural thermal conductivity to extract
geothermal energy to the heat pump. The thermal energy extracted is then elevated by the heat
pump to a level were it can be used for thermal applications in the building. The heat pump is
considered to be an electrical heat pump for this thesis. The GSH system is therefore not arenewable process since the electricity for the pump is delivered from the grid.
The heat pump is assumed to have a coefficient of performance of 4; one unit of electricity
delivers four units of heat.
More information is shown in the GSH section in appendix A1.3 on pages 111-122.
4.4.1 Carbon efficiency
Carbon dioxide reduction is investigated for a ground source heating system when utilizing
GSH for 20% of the Lots Road sites energy demand. The 20% are chosen here only for CO2
reduction comparison between the different energy systems. The reduction in CO2 emissions
is then 9.3%.
The CO2 reduction comparison matrix is shown in Table 2 and the CO2 emission calculations
are shown in appendix B4.4 on page 171.
4.4.2 Urban placement
An evaluation on implement GSH in an urban area was completed.
The key points for implementing GSH are that it can provide thermal energy to buildings inurban areas and that it can utilize different sources to extract energy.
It can for example be designed to extract heat from the river Thames which is located near by
the Lots Road site.
From the London toolkit GSH used in large building will only be utilized to provide a
proportion of the thermal demand [20] because of the long pipe length needed for larger
thermal loads.
4.4.3 Planning permission
Investigation for GSH to obtain planning permission when being implemented on the Lots
Road site was carried out.
The key points are that the visual intrusion for GSH is negligible as it can not be seen from
the outside and that the system is mainly underground with the heat pump in the building.
GSH can therefore be designed to be unobtrusive for the residents to obtain planning
permission. Implementing GSH can require pre-drilling for boreholes (vertical system) to
evaluate the drilling conditions.
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4.4.4 Availability
GSH is considered available and established from the research in this thesis. There are GSH
systems currently providing heat to residents in UK for example to Braddock house in
Nottingham. [21]
4.4.5. Cost
The energy output of 1500MWh/year is chosen here only for cost comparison between the
energy systems. The capital cost for implementing GSH is then £ 900, 000
The cost comparison matrix is shown in Table 3 and the cost calculations are shown in
appendix B5.3 on page 173
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4.5 Photovoltaic (PV)
Photovoltaic utilize the energy from the sun to create electricity. It is the Semiconductors in
the PV panels that convert the suns energy into electricity. Photovoltaic do not release any
carbon dioxide emissions and is a renewable energy source. The photovoltaic panels are
usually placed on the roof, in an angle or flat, facing a southerly direction to absorb as muchenergy as possible.
There are different types of semiconductors and the efficiency varies. Mono crystalline silicon
semiconductors delivers electricity with 15% efficiency, this is one of the highest efficiencies
commercially available. There is also for example the polycrystalline semiconductor which
has a 10% efficiency.
More information is shown in the photovoltaic section in appendix A1.5 on pages 130-136.
4.5.1 Carbon efficiency
Carbon dioxide reduction is investigated for photovoltaic when utilizing PV panels for 20% of
the Lots Road sites energy demand. From the roof space calculation in appendix B2on page
167 there is not enough roof space for PV to generate the 20% energy demand. It is chosen
here only for CO2 reduction comparison between the different energy systems. The reduction
in CO2 emissions is then 27.4%.
The CO2 reduction comparison matrix is shown in Table 2 and the CO2 emission calculations
are shown in appendix B4.5 on page 172.
.
4.5.2 Urban placement
An evaluation on implementing PV in an urban area was completed.
The key points for implementing photovoltaic is the low energy efficiency and it is therefore
difficult to find enough roof space to implant PV panels in order to generate energy. For
example to generate 10% of the Lots Road sites energy demand would require 16000 m2
of
roof space. Maximum roof space available on site from the roof space calculations in
appendix B2 on page 167 is 4100 m2. Finding enough external space to deliver a high amount
of PV electricity is therefore considered impossible.
In order to get an energy efficient PV system it is important to have the PV panels unshadedat all times. They should also be facing in a southerly direction to efficiently absorb the
energy from the sun. The PV efficiency is therefore depending on the roof angle and direction
of the building. Photovoltaic could be placed on the façade but that would lower the
efficiency further.
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4.5.3 Planning permission
Investigation for PV to obtain planning permission when being implemented on the Lots Road
site was carried out.
The key points are that PV panels can be placed on the roof to be integrated to look likeregular roof tiles so the visual impact is minimised.
Photovoltaic is favourably designed to have a minimised visual impact compared to being
designed as a visual renewable energy statement [13] in order to obtain planning permission.
In this thesis if photovoltaic is used it will be designed as a visual renewable energy statement
to raise public awareness even though planning permission could be more difficult to obtain.
4.5.4 Availability
Photovoltaic is considered available and established from the research in this thesis. There are
PV systems currently working efficiently providing electricity in the UK for example to
Bronllys Hospital in Powys, Wales. [22]
4.5.5 Cost
The energy output of 1500MWh/year is chosen here only for cost comparison between the
energy systems. The capital cost for implementing PV is then £ 13, 600, 000
The cost comparison matrix is shown in Table 3 and the cost calculations are shown in
appendix B5 on page 173.
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4.6 Solar Water Heating (SWH)
Solar water heating panels absorbs the energy from the sun to generate thermal energy. It does
not emit carbon dioxide emissions and is a renewable energy source. Collectors are used in
order to collect thermal energy. The two main types are the flat plate collector which utilize a
black absorber plate and the evacuated tube collector which is using black coating on theevacuated tubes. The SWH collector is usually placed on the roof, flat or in an angle, facing in
a southerly direction to absorb as much energy as possible.
More information is shown in the SWH section in appendix A1.4 on pages 123-129.
4.6.1 Carbon efficiency
Carbon dioxide reduction is investigated for solar water heating when utilizing SWH for 20%
of the Lots Road sites energy demand. From the roof space calculation in appendix B2 on
page 167 there is not enough roof space for SWH to generate the 20% energy demand. It is
chosen here only for CO2 reduction comparison between the different energy systems. The
reduction in CO2 emissions is then 16.2%.
The CO2 reduction comparison matrix is shown in Table 2 and the CO2 emission calculations
are shown in appendix B4.6 on page 172.
4.6.2 Urban placement
An evaluation on implementing solar water heating in an urban area was completed.
The key points are that SWH panels on the roofs of the Lots Road site can supply a part of thethermal energy demand but has an unreliable winter performance. Solar water heating panels
therefore needs to be complemented with other energy systems.
In order to be energy efficient the SWH panel should be unshaded at all times and facing in a
southerly direction. This can be difficult in an urban area and is depending on the roof angle
and elevation of the building.
4.6.3 Planning permission
Investigation for SWH to obtain planning permission when being implemented on the Lots
Road site was carried out.
To obtain planning permission the visual impact should be minimised. This is instead of being
design as a visual renewable energy statement [13]. Solar water heating panels can for
example be implemented to look like a roof window.
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4.6.4 Availability
Solar water heating is considered available and established from the research in this thesis.
There are SWH systems currently working efficiently providing heat to buildings in UK for
example SWH panels are placed on Ballyclare [23].
4.6.5 Cost
The energy output of 1500MWh/year is chosen here only for cost comparison between the
energy systems. The capital cost for implementing SWH is then £ 1, 200, 000.
The cost comparison matrix is shown in Table 3 and the cost calculations are shown in
appendix B5 on page 173.
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4.7 Wind power
Wind power is a renewable energy technology and uses the kinetic energy in the wind to
generate electricity. The blades are shaped like an airplane wing and utilize the aerodynamic
forces to rotate. Via an electric generator the wind turbine is then able to create electricity.
More information is shown in the wind power section in appendix A1.6 on pages 137-145.
4.7.1 Carbon efficiency
Carbon dioxide reduction is investigated for wind power when utilizing it for 20% of the Lots
Road sites energy demand. The 20% are chosen here only for CO2 reduction comparison
between the different energy systems. The reduction in CO2 emissions is then 27.4%.
The CO2 reduction comparison matrix is shown in Table 2 and the CO2 emission calculations
are shown in appendix B4.7 on page 172.
4.7.2 Urban placement
An evaluation on implementing wind power in an urban area was completed.
The key points are that large scale wind turbines would be difficult to implement because they
would take up large space over ground and they need none turbulent air to work efficiently.
Large wind turbines need none turbulent wind speeds of approximately 5 to 6 m/s. [24] When
implementing small scale roof based wind turbines on the Lots Road site it would be technical
difficult to connect the large amount of turbines needed to power buildings.
4.7.3 Planning permission
Investigation for wind power to obtain planning permission when being implemented on the
Lots Road site was carried out.
There are many factors to be considered in order to get planning permission for wind power.
Large wind turbines usually need special circumstances to obtain planning permission. [13]
Evaluation of turbine and gearbox noise needs to be assessed and for roof based turbines the
impact of structure borne vibrations needs to be considered. An important factor for noise isto compare the turbine noise to the background noise. If the background noise is high the
impact of turbine noise will be lowered [25]. Other aspects are safety in the event of turbine
failure. This is to make sure the risk of people getting hurt is minimized if for example a
turbine blade loosens.
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Wind turbines as mentioned takes up space over ground and can be noisy. They can also
produce a flickering shadow from rotating turbine blades which could be irritating for the
residents.
There have not been thorough evaluations to determine if planning permission for wind
turbines is possible at the Lots Road site. It is for this thesis considered difficult because of all
the factors mentioned above.
4.7.4 Availability
Wind power is considered available and established from the research in this thesis. There are
wind power systems currently providing power in UK for example to the Antrim area hospital
in Northern Ireland [26].
4.7.5 Cost
The energy output of 1500MWh/year is chosen here only for cost comparison between the
energy systems.. The capital cost for implementing wind power is then
£ 1, 140, 000
The cost comparison matrix is shown in Table 3 and the cost calculations are shown in
appendix B5 on page 173.
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5 Evaluations and system selections
The energy systems are evaluated from the information in the energy systems section and
from the additional information in appendix A & B.
Below is a brief explanation of the evaluation matrixes in this section:
The energy system matrix shows the system size and the energy output for the different
energy systems when achieving the 50 % carbon dioxide reduction for the Lots Road site.
It is also showing notes about the energy systems on for example working hours per year and
coefficient of performance. Investigations into reaching the 50% reduction target shows that it
is difficult to only utilize a single renewable energy without wasting energy or sizing the
system incorrectly. For example placing 120 wind turbines on the Lots Road site is seemed
impossible.
The CO2 reduction matrix shows the carbon dioxide reduction utilizing a selected energy
system for 20% of the sites total energy demand compared to fossil fuelled energy. Utilizing
20% of renewable energies on the Lots Road site is a realistic energy target and has been
chosen only as a comparison for carbon dioxide savings between energy systems.
The Capital cost matrix shows the capital cost of 1500MWh/year for the energy systems in
order to achieve a capital cost comparison. Cost is not of a high priority to this report and the
1500MWh/year is chosen only for cost comparisons between the selected energy systems.
The cost comparison is on the basis that any selected energy output per year will have the
same outcome. For example if PV has the highest capital cost for 1500MWh/year it will have
the highest cost for any selected energy output per year.
After the energy systems evaluation suitable energy systems are selected and then an energy
centre evaluation of the selected energy systems is carried out. It will establish if the selectedenergy systems are suitable in an energy centre.
There is also a brief evaluation and selection of sustainable design systems these systems do
not generate energy but can be used as sustainable design features.
The last part in section five is a block evaluation of the buildings present at the Lots Road site.
The evaluation will determine were onsite the selected systems can be placed and utilized.
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5.1 Evaluation Matrixes
The energy system matrix is showing the system size and energy output for different energy
systems when achieving 50 % carbon dioxide reduction at Lots Road site.
Energy system matrix
CO2 reduction Enery output System size Notes
WindPower 50%
4740MWh/year 120 x 15 kW For 15 kW wind turbines
there will have to be 120
units to meet the energy output
Biomass 50%8041
MWh/year 3655 kW The boilers are assumed to run
2200 hours per year.
This means there can be two1830 kW boilers to meet the energyoutput
CHP 50%24390
MWh/year 2134 kWe CHP with an efficiency of 80%
and a power to heatratio of 1:1.286. Assumed to work5000 hours annually
Biomass
CHP 50%
6164
MWh/year 540 kWe Biomass CHP with efficiency of80% and a power toheat ratio of 1:1.286.Assumed to work 5000hours annually
SWH 50%8041.02
MWh/year17711 m^2
panel The output is approximately
454 kWh/ m^2*year
PV 50%47340
MWh/year50553 m^2
panel The output is approximately
750 (kWh / year)
per 8 m^2 panel
GSH 50%13964
MWh/year 9309 kW COP of 4 working1500 hours annually
Table 1 energy system matrix. Note: (kWe) kilo Watt electricity
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The energy system matrix shows that in order to achieve the 50% CO2 reduction it is easy to
waste energy or size the energy system incorrectly. The numbers coloured in red in the energy
matrix are incorrectly sized systems or where energy will be wasted. For example to reach the
50% CO2 reduction for CHP it will have to deliver 24390 MWh/year which is a lot higher
then the Lots Road site energy demand of 13000MWh/year . This will be evaluated further in
the 5.2 energy system evaluation section.
The CO2 reduction matrix below is showing the carbon dioxide reduction of several different
energy systems when generating 20 % of the energy demand at the Lot Road site.
CO2 reduction matrix
Enery outputCarbon
reduction
Wind Power 2600 MWh/year 27,4 %(20 % of site
demand)
Biomass 2600 MWh/year 16,2 %(20 % of site
demand)
CHP 2600 MWh/year 5,3 %(20 % of site
demand)
Biomass CHP 2600 MWh/year 21,1 %(20 % of site
demand)
SWH 2600 MWh/year 16,2 %(20 % of site
demand)
PV 2600 MWh/year 27,4 %
(20 % of sitedemand)
GSH 2600 MWh/year 9,3 %(20 % of site
demand)
Table 2 carbon reduction matrix
The CO2 reduction matrix above shows an energy system carbon reduction comparison
when delivering 2600 MWh/year. For example wind power and photovoltaic are the
two energy systems that have the highest carbon dioxide reduction for the selected
energies. This is evaluated further in the 5.2 energy system evaluation section.
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Capital cost matrix
Cost £ / kWCapital cost (1500
MWh/year)
Wind 2000 £/kWe 1,140,000 £Power
Biomass 200 £/kWt 140,000 £
CHP 1000 £/kWt 180,000 £
Biomass 2720 £/kWe 380,800 £
CHP
SWH 1460 £/kWt 1,200,000 £
400 £/m^2
PV 2482 £/kWe 13,601,360 £
850 £/m^2
GSH 800 £/kWt 900,000 £
Table 3 showing the cost matrix, Note: kilo Watt electricity (kWe), kilo Watt thermal energy (kWt)
The capital cost matrix above shows a capital cost comparison for the different energy
systems when producing 1500MWh/year and an estimated £/kW installed for the different
energy systems. It can for example be seen that photovoltaic have the highest capital cost of
the selected renewable energy systems. This is evaluated further in the 5.2 energy system
evaluation section.
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5.2 Energy system evaluation
5.2.1 Wind power
To achieve the carbon dioxide reduction target of 50%, hundred and twenty 15 kW wind
turbines are needed and this is considered unrealistic for this thesis. Hundred and twenty windturbines would be very obtrusive for the residents and they would be difficult to place with
fifteen meter long masts and nine meter wide turbine blades. The electricity delivered from
wind power to lower the carbon dioxide reduction with 50% can be used to deliver part of the
sites electrical demand.
From evaluating the carbon dioxide reduction matrix wind power saves a high percentage of
carbon dioxide. The savings are higher then for example biomass and SWH.
In the capital cost matrix wind power is considered expensive compared to for example
biomass and CHP.
From the wind power section it is stated that wind power is used in the UK but planningpermission in urban areas can be difficult. Wind turbines can be noisy, produce flickering and
it takes up space over ground.
Decision:
Wind power will not be selected for the Lots Road site because:
• Reaching the 50 % target while implementing hundred and twenty turbines is
unrealistic.
• Planning permission is difficult to achieve
• Expensive compared to other renewable technologies
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5.2.2 Biomass
The carbon dioxide reduction target of 50% can be achieved from biomass with one 3655 kW
boiler or for example with two smaller 1830 kW boilers. The thermal energy delivered from
biomass can be used to deliver part of the sites thermal demand.
From evaluating the carbon reduction matrix biomass reduces carbon dioxide emissions not as
much as wind power but significantly more then none renewable energy sources such as CHP.
The capital cost matrix shows that the lowest cost to implement an energy system is for
biomass boilers.
More information on biomass fuel and cost are shown in appendix A1.1 on pages 93-99 in the
biomass section.
From the biomass section biomass is currently in use and getting planning permission can be
obtained when designed to be unobtrusive for the residents.
Decision: Biomass will be selected for the Lots Road site because:
• Reaching the 50 % target with biomass is realistic
• It is available and planning permission is seemed possible to achieve
• It has the lowest cost to implement
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5.2.3 Combined Heat and Power
From evaluating the carbon dioxide reduction matrix CHP do not have a high reduction in
carbon dioxide emissions compared to biomass or any of the renewable energy systems.
The carbon dioxide reduction target of 50% can be achieved with a CHP gas engine sized to2134 kW electricity (2134 kWe). The amount of energy wasted would be large and it is
seemed unreasonable to generate CHP for 50% CO2 Savings.
In the capital cost matrix it is shown that CHP have a low capital cost compared to both SWH
and PV.
From the CHP availability and planning permission sections CHP is currently in use and
planning permission can be obtained when being designed to be unobtrusive for residents.
Decision: CHP will be selected for the Lots Road site because:
• Reaching the 50 % target with CHP is seemed unrealistic but it can be used for CO2 savings
• It is available and planning permission is seemed possible to achieve
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5.2.4 Biomass CHP
The carbon dioxide reduction target of 50% can be achieved with a 540 kWe biomass CHP
engine and the energy output can be used onsite to deliver a part of the sites energy demand.
From evaluating the carbon dioxide reduction matrix biomass CHP saves more CO2 thenbiomass but less then for example wind power and PV.
In the capital cost matrix it is shown that biomass CHP is one of the most expensive energy
systems in £ per kW installed but it has a lower capital cost then wind power and
photovoltaic.
From the biomass CHP availability and planning permission sections biomass CHP is not
considered available. This is because there are only onsite test plants of biomass CHP in
urban areas in the UK [18]. Planning permission can be obtained if biomass CHP is designed
to be unobtrusive for the residents.
Decision: Biomass CHP is only considered as a future option it will not be selected for the
Lots Road site because:
• Biomass CHP is not seen available for this report
• It is one of the most expensive renewable technology (£/kW) to implement
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5.2.5 Solar Water Heating
The carbon dioxide reduction target of 50% can be achieved from SWH panels with 177711
m2
of panel. From evaluating the roof space on Lots Road this is unrealistic there are not
enough roof space available.
From evaluating the carbon dioxide reduction matrix the reduction for solar water heating is
similar to biomass.
From the capital cost matrix SWH has a lower implementing cost then photovoltaic and wind
power but is more expensive then ground source heating and CHP.
From the SWH availability and planning permission sections SWH is available and planning
permission can be obtained when being designed to have minimal visual impact.
Decision: SWH will be selected for the Lots Road site as a complement to other energies
because:
• The carbon dioxide reduction savings are similar to biomass
• SWH is available and planning permission is possible.
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5.2.6 Photovoltaic
The carbon dioxide reduction target of 50% can be achieved from photovoltaic panels with
50553 m2
of panel. From evaluating the roof space on Lots Road this is unrealistic there are
not 50553 m2
roof available.
From evaluating the carbon reduction matrix the reduction for photovoltaic is as high as for
wind power.
From the capital cost matrix photovoltaic is the most expensive energy system to implement.
From the PV availability and planning permission sections PV is available and planning
permission can be obtained.
Decision: PV will be selected for the Lots Road site but only to be implemented in small
amounts this is because:
• Carbon dioxide savings for PV is high
• The capital cost is high and the efficiency (W/m2) is low.
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5.2.7 Ground Source Heating
The carbon dioxide reduction target of 50% can be achieved from a GSH system with the
thermal energy output of 14000MWh/year. The GSH system would then waste heat since the
thermal demand for the Lots Road site is 8500 MWh/year. Reducing carbon dioxide
emissions with 50% from implementing GSH is therefore unrealistic.
From evaluating the carbon dioxide reduction matrix GSH do not have a high reduction in
carbon dioxide emissions compared to any of the renewable energy systems.
From the cost matrix GSH is an expensive energy system to implement. This is compared to
for example biomass and CHP.
From the GSH availability and planning permission sections GSH is currently in use and
planning permission can be obtained.
Decision: Ground source heating will not be selected for the Lots Road site because:
• The carbon reduction savings are low
• The CO2 target can not be achieved solely by GSH with out wasting energy.
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5.3 Energy system selection
The energy systems are selected from the energy system evaluation.
The selected energies to be implemented at Lots Road are:
• Biomass
• CHP
• SWH
• Photovoltaic
Future option to implement is:
• Biomass CHP
The excluded energies are:
• GSH
• Wind power
5.3.1 Discussion
From the energy system evaluation the energy systems that will be selected for the Lots Road
site are Biomass, CHP or SWH. Biomass and CHP can be used separately or together withother technologies. Solar water heating is only considered with other energy systems to meet
the thermal energy demand. This is because of the limitation of roof space and that SWH do
not have a good winter performance. Photovoltaic is also chosen to be implemented because it
is a suitable renewable energy technology generating electricity and it will be utilized as a
visual sustainable design feature.
The future option is to use Biomass CHP it is an interesting option to use in urban areas. It has
all the advantages of CHP and is a renewable technology. It can not be recommended for this
thesis since there is no biomass CHP working sufficiently in UK urban areas except for test
plants providing heat and power for residents.
More information on energy systems can be seen in appendix A1 on pages 93-150.
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5.4 Energy centre
To have an energy centre in urban areas providing heat and power for a site is an opportunity
to be energy efficient. It would reduce energy losses from for example buying electricity from
the grid. It is also unobtrusive for the resident from for example having a gas boiler in the flat
since the energy generation would be in a different building or underground.
5.4.1 Energy system evaluation for an energy centre
The definition of an energy centre for this report is energy generation under or over ground
delivering energy to more then one specific block. The evaluation is for the selected energies
from the energy system section.
The energy systems suitable for an energy centre are biomass boilers using biomass fuel and
gas engine CHP using natural gas. They can be placed in an underground energy centre to be
energy efficient and unobtrusive, out of sight, for the residents. The energy centre can also be
placed over ground unobtrusively in a separate building providing thermal power for residents
from biomass or heat and power from CHP.
Solar water heating and photovoltaic panels are not suitable to have in an energy centre for
the Lots Road site. This is because they are placed visible over ground and needs a large
space to produce a large percentage of the Lots Road sites energy demand.
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5.5 Sustainable design systems
Minor studies on sustainable design systems were carried out. It is systems that do not
generate any energy but can be utilized for sustainable design.
Brief system descriptions of green roof, rain water systems and grey water systems are shown
in the sustainable design system section in appendixA2 on pages 151-155.
5.5.1 Selection of sustainable design systems
The decision reached after evaluating the sustainable design systems was that green roof is
selected to be implemented at the Lots Road site.
Green roof is seemed suitable to implement at the Lots Road site because:
• It provides a passive solar design feature that acts as a thermal barrier to solar gain and
provides visual attraction. It is also at the same time a visual sustainable design feature
for the residents.
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5.6 Site evaluation
As mentioned earlier in the report the Lots Road site consists of nine blocks.
A site evaluation of the blocks are carried out on the basis of where and if the selected energy
systems can be implemented. All the figures are from the architectural drawings 2001 [5].
5.6.1 Block JJ (Power station)
If SWH panels or PV panels are placed on block JJ it should be placed in a southerly direction
and preferably in an angle to be energy efficient. See the SWH and the photovoltaic section in
appendix A1.4 & A1.5 on pages 123-136 for more details.
The power station has angled roofs which can be used to place solar water heating and
photovoltaic panels on. Photovoltaic is not considered suitable to be put on the façade because
it lowers the PV panel efficiency.
The angled roof facing in a northerly direction can be used for green roofs.
Biomass boilers and CHP if used in Block JJ would be placed in the basement. This is if
power is not distributed to the block from an energy centre. Since Block JJ is a large
residential block the basement is considered large for this report. Space in the basement is
essentials to fit the physical boiler and CHP engine as well as for biomass fuel storage. CHP
or biomass boilers are therefore considered suitable for Block JJ. See the biomass and CHP
section in appendix A1.1 & A1.2 on pages 93-110for more energy system details.
5.6.1.1 Direction
Direction of Block JJ is shown below.
Figure 5 Overview and direction of Block JJ
River
Thames
Creek
North Side
South Side
JJ
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It is important to know the direction of the building in order to evaluate where and if
renewable energies can be used, for example placement of solar water heating on the roof.
JJ is the front view it is shown below in the architectural drawings.
5.6.1.2 Architectural Drawings Block JJ
Figure 6 JJ - Front view
The old power station will be turned in to dwellings with approximately 237 units. There will
also be a small part of retailing and offices in the building. The Power Stations is here shown
in different views.
Figure 7 Top view of block JJ
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Figure 8 Left side view of block JJ
The Power station is approximately 135 meters long and 55 meter wide.
5.6.2 Block HH
Block HH has a flat roof and one option is to place SWH or PV panels flat on the roof or
arrange the panels in an angle for higher efficiency. Photovoltaic is not considered suitable to
be put on the façade because it lowers the PV panel efficiency.
Planting green roof on block HH would provide heat gain protection and is a visual
sustainable design solution.
Small biomass boilers and CHP units placed in the basement could be a suitable suggestion to
provide energy to block HH. Obstacles are that CHP is more favourable when there is a high
yearly heat demand and that if biomass boilers are utilized there needs to be sufficient space
for biomass fuel storage. See the biomass and CHP section in appendix A1.1 & A1.2 on pages
93-110 for more energy system details.
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5.6.2.1 Direction
Figure 9 Site overview and front view direction of Block HH
HH is the front view it is shown in the architectural drawings.
5.6.2.2 Architectural Drawings Block HH
The “Horse shoe” is directed towards the Power station and has the North tower to the left. In
Block HH there will be residential flats and a small part of retailing. Block HH is here shown
in different views.
Figure 10 HH - Front view
H
H
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Figure 11 Top view of block HH
Figure 12 Left side view of block HH
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5.6.3 Block GG
Block GG is the north tower and the tower roof is in a 45° angle facing southwest. Solar water
heating or photovoltaic panels could work efficiently placed on the roof.
Green roofs could be planted on Block GG but the steep angle of the north tower roof is
considered as an obstacle.
Small biomass boilers and CHP units placed in the basement could be a suitable suggestion to
provide energy to block GG. Obstacles are that CHP is more favourable when there is a high
yearly heat demand and that if biomass boilers are utilized there needs to be sufficient space
for biomass fuel storage. See the biomass and CHP section in appendix A1.1 & A1.2 on pages
93-110 for more energy system details.
5.6.3.1 Direction
Figure 13 Overview of block GG and front view direction
GG is the front view it is shown in the architectural drawings.
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5.6.3.2 Architectural Drawings Block GG
The north tower is located by river Thames and has a rhomb like design. The tower will be for
residential usage and a small part of retailing. Block GG is here shown from different views
Figure 14 GG - Front view
Figure 15 Top view
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Figure 16 Right side view
5.6.4 Block FF
Block FF is the south tower and the tower roof is in a 45° angle facing northeast. Solar water
heating and photovoltaic panels are not considered suitable for Block FF. The direction of the
roof makes the efficiency of SWH and PV to low. See appendix A1.4 & A1.5 on pages 123-
136 for more detail about SWH and PV efficiency.
Photovoltaic panels placed on the façade lowers the PV panel efficiency compared to roof
mounted panels. It could be placed on block FF on the facade for public awareness since the
roof is not suitable for SWH or PV panels.
Green roof is not considered suitable for Block FF the steep angle of the south tower roof is
considered as an obstacle.
Small biomass boilers and CHP units placed in the basement could be a suitable suggestion to
provide energy to block FF. Obstacles are that CHP is more favourable when there is a high
yearly heat demand and that if biomass boilers are utilized there needs to be sufficient space
for biomass fuel storage. See the biomass and CHP section in appendix A1.1 & A1.2 on pages
93-110 for more energy system details.
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5.6.4.1 Direction
Figure 17 Overview and front view direction of block FF
FF is the front view it is shown in the architectural drawings.
5.6.4.2 Architectural Drawings Block FF The South tower is located by river Thames and has a rhomb like design. The tower will be
for residential usage and a small part of retailing. Block FF is here shown from different
views
Figure 18 FF - front view
River
Thames
Creek
North Side
South Side
F
F
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Figure 19 Top view of block FF
Figure 20 Left side view of block FF
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5.6.5 Block AA to EE
The five blocks are considered to have similar possibilities for energy generation.
They all have flat roof where SWH or PV panels can be placed flat on the roof or for higher
efficiency angled in a southerly direction.
Photovoltaic is not considered suitable to be put on the façade because it lowers the PV panel
efficiency.
Planting green roof on the blocks are another solution working as thermal barrier and as a
visual sustainable design feature.
For the blocks AA to EE biomass boilers for heating and CHP for heat and power is a
possibility. They could be placed in the basements of the different buildings but the buildings
are small compared to the rest of the blocks. Limitations are therefore space for biomass fuel
storage as well as the small heat demand if using CHP.
5.6.5.1 Direction Block EE
Figure 21 Overview and the front view direction of block EE
EE is the front view it is shown in the architectural drawings.
River
Thames
Creek
North Side
South Side
E
E
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5.6.5.2 Architectural Drawings Block EE
Block EE has a rectangular design and will contain residential units only.
Block EE is here shown from different views.
Figure 22 EE - Front view
Figure 23 Top view for block EE
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Figure 24 Back view of block EE
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5.6.5.3 Direction Block DD
Figure 25 Overview and direction of front view for block DD
DD is the front view it is shown in the architectural drawings.
5.6.5.4 Architectural Drawings Block DD
Block DD has a rectangular design and will contain residential units only.
Block DD is here shown from different views.
Figure 26 DD - Front view
River
Thames
Creek
North Side
South Side
DD
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Figure 27 Top view of block DD
Figure 28 Back view of block DD
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5.6.5.5 Direction Block CC
Figure 29 Overview and direction of front view for block CC
CC is the front view it is shown in the architectural drawings.
5.6.5.6 Architectural Drawings Block CC
Block CC has a quadratic design and will contain residential units only.
Block CC is here shown from different views.
Figure 30 CC - Front view
River
Thames
Creek
North Side
South Side
CC
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Figure 31 Top view of block CC
Figure 32 Back view of block CC
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5.6.5.7 Direction Block BB
Figure 33 showing overview and direction of the front view for block BB
BB is the front view it is shown in the architectural drawings.
5.6.5.8 Architectural Drawings Block BB
Block BB has a rectangular design and will contain residential units only.
Block BB is here shown from different views.
Figure 34 BB - Front view
River
Thames
Creek
North Side
South Side
B
B
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Figure 35 Top view of block BB
Figure 36 Back view of block BB
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5.6.5.9 Direction Block AA
Figure 37 showing the overview and direction of front view for block AA
AA is the front view it is shown in the architectural drawings.
5.6.5.10 Architectural Drawings Block AA
Block AA has a specific architectural design which is shown below and will contain
residential units only.
Block AA is here shown from different views.
Figure 38 AA - Front view
River
Thames
Creek
North Side
South Side
A
A
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Figure 39 Top view of block AA
Figure 40 Back view of block AA
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6 Energy Strategy
This section will recommend an energy strategy for the Lots Road site.
From the energy systems evaluations the energy systems that are considered for Lots Road are
biomass, CHP and solar water heating. There are also possibilities to utilize photovoltaic andgreen roof in small amounts.
6.1 Lots Road Energy demand
6.1.1 Lots Road site
From the calculations in appendix B9 on page 191 the Lots Road site energy demand is
approximately 13000MWh/year. The thermal demand is then estimated to 8500MWh/year
and the electrical demand to 4500MWh/year)
The sites peak load is the instant thermal and electrical load the energy systems need to
deliver. It is calculated from Hoare Lea Consulting rule of thumb and is for the thermal
energy 5kW per flat which equals a thermal peak load of 3515 kW. For the electrical peak
load it is 2kW per flat which equals a peak load of 1406 kW [29]. The peak loads are low
because they are estimated with diversity over the site. Peak load calculations and diversity
explanations are shown in appendix B1 on pages 165-166.
The thermal base load is calculated in appendix B1 on page 166 to 1400 kW. It is calculated
from the minimum domestic hot water (DHW) demand per flat on the Lots Road site. The
thermal base load is the minimum load for the site and this is usually during the summer when
no heating is needed. This is why it is calculated on the DHW demand as mentioned above.
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6.2 Energy Strategy Option A
The first option (Option A) for an energy strategy for the Lots Road site is:
• Two CHP gas engines to supply the base load. One on each side of the creek connected to all the blocks on respective side. CHP is sized for the base load to not
waste heat.
• Nine biomass (solid fuel) boilers e.g. one in each block. Possible to supply the rest of
the thermal load after the addition of CHP.
• Solar water heating panels are placed on roofs across the site. Roof space evaluation
from the architectural drawings concludes that SWH can supply 20% of the yearly
thermal demand. [5]
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6.2.1 Evaluation Option A
The CHP engines will have a power to heat ratio 1:1.286 with an efficiency of 80%. It will for
every unit of electricity deliver 1.286 units of heat. The CHP engine is sized for the base load
so it will therefore deliver 1400 kW thermal energy and 1088.65 kW of electricity. The
calculation for delivered electricity is shown below
0.777 x 1400 = 1088.65 kW electricity Equation (3)
Biomass boilers are sized to meet the peak load subtracting the addition from CHP. Solar
water heating system has an unreliable winter performance it can therefore not be sized on the
peak load. The biomass boiler size will be 2115 kW from the calculations below.
3515 kW – 1400 kW = 2115 kW Equation (4)
If each boiler is preliminary of the same size there will be nine 240 kW boilers.
For this recommendation the CHP is sized on the rule of thumb that CHP should be working
approximately 5000 hours per year [30] to be economical viable. This means the CHP would
minimum generate 7000MWh/year thermal energy from the calculation below.
1400 x 5000 = 7000MWh/year Equation (5)
The biomass boilers would then deliver the rest of the yearly energy demand of
1500MWh/year.
From the CHP and biomass evaluation above SWH systems are redundant so it is no longer in
this recommendation.
The CHP engine would also minimum generate 5443MWh/year electricity.
1088.65 x 5000 = 5443MWh/year Equation (6)
This is almost 1000MWh/year electricity that needs to be sold back to the grid to not waste
energy since the total electrical demand is 4500MWh/year.
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6.2.2 Advantages and Disadvantages of Option A
The tables below are showing advantages and disadvantages of Option A
Table 4 Option A advantages
Table 5 Option A disadvantages
Disadvantages
- Delivery of biomass fuel to all
blocks.
- No backup if biomass fuel
deliveries fail.
-Storage of bio-fuel in each block
- Biomass as fuel source is still
considered unreliable
-Labour intense with boilers in each
block and the CHP engines.
-CHP is not a renewable energy
technology
-Selling electricity to the grid is
costly
Advantages
+If biomass boiler fails CHP can
provide some thermal energy during
winter time.
+If one boiler fails it’s a small % failure
+ South and north side have independent
energy generation
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6.2.3 Target
The target is a 50% carbon emission reduction for the Lots Road site and that is
approximately 2000000 kg CO2 / Year
The calculation to obtain the CO2 reduction uses the boiler efficiency data of 78% and theconversion factors from SAP 2005 [27]. The conversion factor for natural gas is 0.194
CO2kg/kWh and for electricity from the grid 0.422 CO2kg/kWh.
Biomass will then save:
(1500000/0.78) x 0.194 = 373076 kgCO2 /Year Equation (7)
CHP will then save:
((7000000/0.78) x 0.194 + (7000000 x 0.777) x 0.422) –
((12439000/0.8) x 0.194) = 1019826 kgCO2 /Year Equation (8)
Total carbon emission savings are then:
1019826 + 373076 = 1392902 kgCO2 /Year Equation (9)
This is a carbon dioxide reduction of:
(1392902/4000000) x 100= 34.8% Equation (10)
Conclusion: Target is NOT achieved
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6.2.4 Option A energy distribution
Figure 41 showing the energy distribution for Option A
Above is the simplified figure of the energy distribution for Option A. It is showing a biomass
boiler in each block and the two CHP engines. There are also a simplified distribution
network (the red line) for the CHP engines.
River
Thames
Creek
North Side
South Side
Biomass boilers in basements of
buildings
CHP in basements of buildings CHP distribution network
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6.2.5 Decision
The target is not achieved and it is necessary with some backup for the biomass boilers in case
of, for example, the fuel delivery is delayed.
To have a biomass boiler in each block that needs maintenance is labour intense and theboilers and fuel storage takes up space in all buildings.
The CHP engine is over sized and ends up wasting electricity or selling electricity back to the
grid. This it is not favourable because the CHP engine is using gas and is emitting carbon
dioxide.
Solar water heating panels can be placed on the roof to supply 20% of the thermal demand.
SWH panels are favourable to implement since they are renewable energy technology but
when using both SWH and CHP it can be difficult to not waste heat. Solar water heating is
most effective during the summer when the heat demand is at its lowest and the CHP engine
is sized to run a minimum 14 hours a day (5000 hours per year). Therefore if SWH and CHP
are utilized together there will have to be large heat storage. No heat waste calculations havebeen carried out when utilizing both CHP and SWH at the Lots Road site because of the time
limit for this thesis.
Photovoltaic panels generating electricity and green roofs can be utilized onsite as sustainable
design features.
Decision: Options A needs to be reviewed
Key points
• The50% CO2 target is not achieved
• CHP is not a renewable energy source
• The heat and power output from the CHP engine do not match the sites energydemand. Electricity needs to be sold back to the grid.
• Biomass needs backup
• Biomass boilers in each block is labour intense
• SWH is not used but can be implemented
• Photovoltaic and green roofs are not utilized.
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6.3 Reviewing Option A
In Option A combined heat and power is delivering a major part of the thermal and electrical
demand. CHP is after the review excluded because the carbon dioxide emission savings target
of 50% is not reached. The energy output of CHP is also difficult to match with the Lots Roadsites energy demand and when sized for the base load electricity has to be sold back to the
grid.
Instead of CHP the thermal energy demand is going to be delivered from biomass boilers and
SWH panels. The biomass heat output will increase to 80% of the sites thermal demand with
SWH still sized to deliver 20% of the sites thermal demand.
From Option A there is a biomass boiler in each block it is after the review changed into two
energy centres one on each side of the creek. The two sides are kept independent so if one
energy centre needs maintenance the other one will continue to deliver energy unaffected. No
thorough infrastructure investigation has been carried out because of the time limit for this
thesis.
From Option A biomass is used without any backup but it is considered necessary to have
some sort of backup when delivering biomass fuel to urban areas. This will secure the thermal
energy supply to the residents if for example the fuel deliveries are delayed.
From the case study of the district heating scheme in Barnsley Metropolitan Council the
backup is 50% and delivered from gas boilers [28]. After the evaluation, an energy centre for
this thesis is selected to also have a backup of 50% delivered from gas boilers.
Two biomass boilers and one backup gas boiler will be situated in each energy centre to
provide thermal energy to the site. The backup gas boiler will have the same energy output asthe biomass boilers. If one biomass boiler needs maintenance the gas boiler will then be able
to provide 100% backup.
In Option A there are no photovoltaic panels delivering electricity or any green roof providing
thermal barrier for buildings. For the reviewed Option A there will be implementations of
green roof and photovoltaic panels. The green roof will provide heat gain protection and act
as a sustainable design feature for the residents. The photovoltaic panels will deliver a small
amount of electricity and similar to the green roof act as a sustainable design feature.
Photovoltaic will also be placed around the site to power street lights and signs as part of
sustainable design.
It is seemed favourable to implement a small amount of electricity since CHP has beenexcluded and the most of the electricity have to be bought from the grid.
Buying electricity from the grid is considered as a temporary solution. There is no renewable
energy technology considered suitable to deliver the electrical demand for the Lots Road site
at the moment.
The reviewed option A is called Option B. Option B is considered as the final
recommendation for the Lots Road site.
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6.4 Option B
6.4.1 The final recommendation
The final recommendation (Option B) for the Lots Road site energy strategy is:
• Two energy centres one on each side of the creek to produce energy.
• The energy centres will have biomass boilers providing 80% of the thermal demand.
• Solar water heating panels providing 20% of the thermal demand.
• In the energy centres there will be backup gas boilers that are able to provide 50% of the thermal peak load.
• Photovoltaic will be placed on the roof of a building to provide electricity it will alsobe placed on street lights and signs.
• Green roof is placed on buildings as a thermal barrier and for public awareness of
sustainable design.
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Biomass and SWH will deliver 100 % of the thermal energy demand and as mentioned earlier
the thermal energy distribution for Lots Road will be 80 % from biomass boilers and 20%
from SWH panels.
6.4.2 Biomass
Since the solar water heating panels winter performance is unreliable the biomass boilers
needs to be sized to provide 100% of the thermal peak load.
The thermal peak load is divided for the north and the south side the peak load calculations
are shown in appendix B1 on pages 165-166.
The peak load for the north side is 2240kW and it will be delivered by two 1200 kW boilers.
The peak load for the south side is 1275 kW and it will be delivered by two 700 kW boilers
Figure 42 The north and south side loads delivered from biomass boilers
1200 kW
1200 kW
BB
BB
2240 kW
700 kW
700 kW
BB
BB1275 kW
North side
South side
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6.4.3 Solar water heating
Solar water heating will provide 20% of the thermal demand which is approximately
1700MWh/year. Energy output for SWH panels and roof space calculations are shown in
appendix B2 on page 167.
Figure 43 The SWH output delivered to the Lots Road site
6.4.4 Control of delivered thermal energy
The yearly peak load is 3515 and that is the instant thermal energy the energy centres have to
deliver. The energy centres will deliver:
2 x 1200 kW + 2 x 700 kW = 3800 kW Equation (11)
From the equation above the energy centres will deliver 3800 kW. Conclusion they can
deliver the thermal peak load.
Block AA SWH
SWHBlock BB
Block DD
Block EE
Block CC SWH
SWH
SWH
SWHBlock JJ
Over 1700 MWh/year
~ 1700 MWh/year
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Electricity delivered from the grid and a small amount of photovoltaic panels will deliver
100% of the sites electrical demand. Photovoltaic will approximately deliver 2.6% of the sites
demand.
6.4.5 Photovoltaic
Photovoltaic panels are placed on the north tower roof (Block GG) and will deliver
117.2 MWh/year. The photovoltaic calculations are shown in appendix B3 on page 168.
Figure 44 The PV output delivered to the Lots Road site
The electricity generated from photovoltaic on signs and street lights are very small, the total
amount of energy produced from photovoltaic on the Lots Road site are 117.2 MWh/year.
The rest 97.4% are then bought from the grid to meet the electrical demand it will deliver
4382.8 MWh/year.
6.4.6 Control of delivered electrical energy
The electricity bought from the grid will be sized to meet the electrical peak load of 1406kWe
and will deliver approximately 4382.8MWh/year. The photovoltaic panels will deliver
approximately 117.2MWh/year and this equals an electrical output of:
4382.8 + 117.2 = 4500MWh/year Equation (12)
Conclusion the output of 4500MWh/year meets the electrical energy demand for the Lots
Road site.
Streetlights
Signs
Block GG
117.2 MWh/year
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6.4.7 Backup
Backup gas boilers are installed to provide thermal energy if there is any technical problems
with the biomass boilers or if there is unforeseen fuel delivery delays. It is sized to 50% which
is considered reasonable since there are urban sites in the UK utilizing biomass with a 50%
backup. One biomass boiler in each energy centre can be switched off and the energy centreswould still deliver 100% of the thermal energy demand with the help of the gas boilers.
Gas boilers are used as backup on the north side and the peak thermal load is 2240 kW. The
gas engine will provide 50% of the thermal peak load which 1120kW so there will be one
1200kW gas boilers as backup in the north energy centre.
Gas boilers are also used as backup on the south side and the peak thermal load is 1125kW.
The gas engine will provide 50% of the thermal peak load which is 637.5kW so there will be
one 700kW gas boiler as backup in the south energy centre.
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6.4.8 Target 50% CO2 reduction
The target is a 50% carbon emission reduction for the Lots Road site and that is
approximately 2000000 kg CO2 / Year
The calculation to obtain the CO2 reduction uses the boiler efficiency data of 78% and theconversion factors from SAP 2005 [27]. The conversion factor for natural gas is 0.194
CO2kg/kWh and for electricity from the grid 0.422 CO2kg/kWh.
Biomass will then save:
(6800000/0.78) x 0.194 = 1691282kgCO2 /Year Equation (13)
SWH will then save:
(1700000/0.78) x 0.194 = 422820.5kgCO2 /Year Equation (14)
Photovoltaic will then save:
117200 x 0.422 = 49458.4kgCO2 /Year. Equation (15)
Total carbon emission savings are:
1691282 + 422820.5 + 49458.4 = 2163560.9kgCO2 /Year Equation (16)
This is a carbon dioxide reduction of:
(2163560.9/4000000) x 100= 54.5% Equation (17)
Conclusion: Target is achieved
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6.4.9 Placement of energy systems on the Lots Road site
The energy centres are placed under ground one on the north side and one on the south side.
Each energy centre will contain two biomass boilers and one gas backup boiler and space for
biomass fuel storage.
Solar water heating is placed on block JJ, EE, DD, CC, BB and AA in a southerly direction
and photovoltaic is placed on the angled roof of block GG in a southerly direction.
Green roof is placed on block HH and on available north facing roof of block JJ.
The placement of the energy systems and green roofs are shown in figure 45 and 46.
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F i g ur e 4 5 s h o wi n g t h e
n or t h s i d e e n e r g y c e n t r e a n d b ui l d i n g s
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F i g ur e 4 6 s h o wi n g t h e s o u t h s i d e e n e r g y c e n t r e a n d b ui l d i n g
s
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7 Schematics and Drawings
The schematics for the two energy centres that are recommended for the Lots Road site are
showing system configurations for thermal energy distribution. They are showing the biomass
boilers, the backup gas boilers and the solar water heating configuration.
In the drawing section there are simplified drawings of thermal and electrical energydistribution to the buildings and flats.
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F i g ur e 4 7 S c h e m a t i c s o v e r t h e s o u t h e n e r g y c e n t r e .
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F i g ur e 4 8 S c h e m a t i c s o v e r t h e n or t h e n e r g y c e n t r e
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7.1 Legend Explanation
The symbols utilized in the north and south energy centre schematics are briefly explained
below.
Flat plate heat exchanger:
The heat exchanger is used to transfer thermal energy from the energy systems to the
residential unit so it can be utilized.
Isolation valve (open):
The isolation valve is always open during system operation. It will only be closed in
emergencies or during maintenance.
Pump:
The pump drives the energy system and circulates the water in the closed boiler system.
One direction flow valve:
The one direction flow valve can only have water flowing through it in one direction. This is
to ensure that there is no back flow into boilers or pumps.
Flexible connection:
The flexible connection acts as a damper and protects the system from pump vibrations.
Mass flow measuring point:
The mass flow measuring points are points on the system where the mass flow can be
manually measured.
Inverter:
The inverter controls the mass flow rate in the system. It helps to saves energy by lowering
the electricity usage of the pump if the mass flow rate is too high.
Pressure sensor:
The electrical pressure sensor is connected to a control panel where the pressure can be
supervised.
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Temperature sensor:
The electrical temperature sensor is connected to a control panel where the temperature can be
supervised.
Isolation valve (closed):
The closed isolation valve is always closed during system operation. It will only be opened in
emergencies to bypass boilers or during maintenance.
7.2 Schematics Explanation
7.2.1 Solar water heating
In the energy centres there are SWH thermal storage. It will store thermal energy from for
example the day to the evening when the residents need to shower. The thermal storage is a
well insulated water tank.
The solar water heating panels are not shown but they absorb energy and deliver the energy in
form of warm water. This is shown in the return flow for SWH in the schematics. The warm
water delivered from the SWH panels can differ from 80° Celsius on a warm summer’s day to
15° Celsius during winter time. If the water is colder than 15° Celsius the SWH system is
bypassed because no thermal energy can be extracted.
The heat exchanger uses the thermal energy from the return flow of the SWH system and
transfers it to the main water supply line. The water supply is connected to the thermal waterstorage in the energy centre.
From the thermal storage the warm water is supplied to the buildings into the flats small
DHW storages. The warmed water from the SWH system is utilized for preheating the DHW.
In the simplified drawings there is more information on the flats energy distribution.
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7.2.2 Biomass and gas boilers
The two energy centres are both utilized with two biomass boilers, one gas boiler, biomass
thermal storage and space for a biomass fuel supply. The thermal storage is similar to the
SWH storage (also located in the energy centre).
The biomass boilers are feed with biomass fuel while the backup gas boiler has a main gas
pipe connection for when backup is needed.
The closed water system is driven by the pump. The system is controlled by sensors to ensure
it has the right pressure and temperature before entering the biomass boiler.
The water is then heated and after exiting the boiler sensors controls the mass flow rate,
pressure and temperature so the right amount of thermal energy is being delivered.
The heated water then enters the header where it is lead into the thermal storage. The thermal
storage is being heated when the boiler system is delivering thermal energy during lower heat
demands. The thermal store can then help to deliver thermal energy to residents duringunexpected peak loads.
A secondary reason to use the thermal store is that boilers prefer to work under optimal
conditions instead of being turned on and off. This helps to ensure a longer boiler life and
shortens boiler maintenance.
If there is a high heat demand and the thermal store is empty it can be bypassed so the system
directly provides thermal energy for the buildings. The temperature range can be varied for
the boilers in the schematics it is chosen to 80° Celsius. The temperature output range for tap
hot water has to be over 60° Celsius for the risk of legionella [31]. The SWH flow does not
have to be over 60° Celsius since it is only for preheating.
The flow is then pumped to the buildings where it dissipates its thermal energy through a flat
plate heat exchanger. See the simplified drawing section for more detail.
The return water from the buildings is returned to the energy centre through a header. It enters
the header with a temperature of around 60° Celsius and is then pumped back to the boiler to
restart the closed system cycle.
The backup gas boilers are connected similar to the biomass boilers in the energy centres. All
the boilers are connected parallel to each other. The only difference is that the gas boiler uses
natural gas instead of biomass fuel. It can sufficiently replace one of the two boilers to meet
the total thermal demand.
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7.3 Drawings
Figure 49 Block GG electrical connection
7.3.1 Explanation of electrical energy distribution
The photovoltaic panel is connected to the balance of the system so the electricity generatedfrom the PV panel can be utilized in the building. The BOS contains an invert to change the
DC from the panel to useful AC. It is then connected to the switch board where the PV
electricity helps to meet the peak load from different building services such as pumps and
lifts. The PV electricity is utilized to lower the amount of electricity bought from the grid.
The major part of the electricity delivered to the building is bought from the grid and is
transformed to useful 230 Volts electricity. It is connected to the switch board were it is
distributed to every floors and every flat through an electrical riser, rising from the bottom to
the top of the building. The electricity from the grid also powers the building services with
some help from photovoltaic as mentioned earlier.
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Figure 50 Thermal connection to block JJ
7.3.2 Explanation of thermal distribution
The thermal energy from the solar water heating panel is connected, through a water system,
to the thermal storage tank in the energy centre. It dissipates heat through a heat exchanger
and is then circulated back to absorbed more energy. The warmed water from SWH is then
circulated to every floor and every flat were it is used for preheating the DHW.
The closed boiler system is connected to every floor and every flat in the building. The flow
absorbs thermal energy from the biomass boilers and dissipates it in the building. It is then
returned to the energy centre to restart the process
SWH Panel
Block JJEnergy Centre
SWHReturn
SWHFlow
Warm waterpre-heated
from SWH
Flow and Return
Closed boiler system
Thermal energy
Distributed to Flats
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Figure 51 showing a residential unit energy distribution
7.3.3 Explanation of energy distribution to a residential unit
The electricity is delivered from the electrical riser to each flat. It is connected as a standard,
hole in the wall, connection.
The thermal connection has the preheated warm water delivered to each residential unit’s
domestic hot water storage. The small domestic hot water storage is then heated by the closed
boiler system to over 60° degrees Celsius because of the risk for legionella in tap hot water.
The boiler system transfer heat from a flat plate heat exchanger to the DHW storage. It also
heats the under floor heating system that are used for space heating in the flats.
Residential Unit
DHW Storage
Flat plate heatexchanger
Warm water pre-heated
from SWH
Flow and Return fromclosed boiler system
Hole in the wall
Electricalconnection
Under floor heating
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9 Discussion
Biomass is selected to deliver most of the thermal energy demand and will reduce carbon
dioxide emissions. It is selected on the basis that it does not increase carbon dioxide emissions
into the atmosphere and that the energy system output is not limited to for example fuel
storage space. The evaluation of capital cost shows that the cost to implement biomass is lowcompared to other renewable energy systems. Considering these factors biomass is the
technology to implement on the Lots Road site.
When utilizing biomass boilers it is the biomass fuel source and delivery that is considered
unreliable. The time frame of this thesis has restricted a thorough biomass fuel investigation.
Backup of 50 % delivered from gas boilers are used and is considered necessary since
biomass fuel delivery can be from remote locations. This report as mentioned earlier has not
investigated carbon dioxide emissions that will be emitted during fuel delivery.
The capital cost is not a high priority for the report but is showing how much it would cost to
implement a system. This favours biomass, CHP and biomass CHP since the fuel cost for
these energy systems are not incorporated in the capital cost or in the evaluation when
selecting suitable energy systems.
Solar water heating panels are implemented to deliver 20% of the yearly thermal demand.
When utilizing several energy sources it reduces the risk and the need of a 100% backup for
the biomass boilers. A solar water heating advantage compared to biomass is that the fuel
does not need to be bought.
Unfortunately SWH can not deliver 100% of the energy demand since it is relying on
absorbing the energy from the sun. The solar water heating energy output peaks during the
summer and is low during the winter. Biomass is therefore sized to meet the peak load since it
occurs during the winter months.
The limitation in time has meant that no annual energy output study for SWH have been
carried out. Unfortunately information found for SWH winter performance was very limited.
What can be said is that SWH is currently working in the UK and is known to have good
summer performance. It can in some occasions provide the entire base load during the
summer.
Photovoltaic is implemented to generate electricity to the site so not all electricity has to be
bought from the grid. Photovoltaic will also act as a sustainable design feature. These are the
reasons fore implementing PV even though it has low energy efficiency and a high capital
cost.
It is placed on block GG because of the south facing angled roof. The roof is elevated and this
decreases the risk of the panels getting shaded. The answer to why PV panels are placed on
block GG is that the angled roof enables the PV panels to work with as high efficiency as
possible.
Green roof is placed on block HH because it will prevent heat gain and will be a visual
attractive design feature on the Lots Road site. These are the reasons why green roof are
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implemented on block HH. It is seemed favourable to have different sustainable design
features across the site.
This thesis uses simplified data to reach satisfying results. In appendix B9, in the technical
data section, on pages 187-191 offices and retails energy demand are stated. They are only
utilized to calculate the total energy demand. Lots Road is then assumed to be a residential
site when calculating the peak and base load.
The carbon dioxide target for the report was set to 50% it is a high target that is reached in the
final recommendation. In the report the boiler efficiency of 78% and the carbon dioxide
conversion factors are taken from SAP 2005. This is the standard assessment procedure
published by the British government to assess building energy performance.
One of the tasks for this report was to find up to date information about renewable energies.
Information and data was mostly gathered from the internet and for some sources it has been
difficult to validate the credibility. The internet was used as the primary information source
since the thesis was carried out at a company with a small renewable information database. To
do the thesis at Hoare Lea Consulting had benefits in form of using the engineering
knowledge and experience in renewable energies and building design.
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10 Conclusion
The thesis shows that carbon dioxide reduction can be achieved from several energy systems.
The energy strategy recommended reaches the 50% CO2 reduction target by utilizing a
combination of renewable energy systems.
The final recommendation will implement biomass boilers and solar water heating panels to
generate 100 % of the thermal energy demand for the Lots Road site.
The conclusion is that biomass boilers will be utilised at the Lots Road site. They are a
favourable option to use in urban areas in the UK when considering carbon dioxide savings,
energy output and the low capital cost of implementing biomass. The final recommendation is
not considering biomass fuel delivery which should preferably be from a biomass fuel source
close to the site or the cost of biomass fuel.
Solar water heating panels are considered as a good alternative when implementing renewable
energies in an urban area in the UK. It delivers thermal energy and can be used as in the final
recommendation for preheating. The limitation for solar water heating is that it must be
combined with other technologies to deliver the total thermal demand.
Photovoltaic panels are implemented in the final recommendation to lower the amount of
electricity being bought from the grid and to be a visual sustainable design feature. The
energy efficiency for photovoltaic are low and it can therefore only deliver a small amount of
electricity to the site.
To buy electricity from the grid is still the favourable option for buildings in urban areas this
is because it is available and reliable. It will continue to be the favourable option until PV
becomes more efficient or until wind turbines can be implemented unobtrusively in urban
areas. Another option is biomass CHP it will generate both heat and power. Biomass CHP isused in other parts of Europe and will probably be more available in the UK in the future.
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List of Figures
Figure 1 Methodology flow diagram ...................................................................................................................... 4 Figure 2 Over view of the site ................................................................................................................................. 6 Figure 3 The Lots Road south side.......................................................................................................................... 7 Figure 4 The Lots Road north side ........... .............. ............. ............. ............. .............. ............. ............ .............. ..... 7 Figure 5 Overview and direction of Block JJ .......... .............. ............. .............. ............ ............. .............. ............. . 39 Figure 6 Block JJ - Front view ............ ............ .............. .............. ............. ............ .............. ............. .............. ....... 40 Figure 7 The Top view of block JJ ........... .............. ............. ............. ............. .............. ............. ............ .............. ... 40 Figure 8 The Left side view of block JJ ................................................................................................................ 41 Figure 9 Overview and front view direction of Block HH ............. ............ .............. ............. .............. ............ ...... 42 Figure 10 Block HH Front view ........... .............. ............ .............. ............. ............ .............. ............. .............. ....... 42 Figure 11 The Top view of block HH ................................................................................................................... 43 Figure 12 The Left side view of block HH ........................................................................................................... 43 Figure 13 Overview of block GG and front view direction .................................................................................. 44 Figure 14 Block GG Front view ........... .............. ............ .............. ............. ............ .............. ............. .............. ....... 45 Figure 15 The Top view of Block GG .................................................................................................................. 45 Figure 16 The Right side view of Block GG .............. ............. .............. ............ .............. ............. ............ ............. 46 Figure 17 Overview and front view direction of block FF ............. ............ .............. ............. .............. ............ ...... 47 Figure 18 Block FF front view .............................................................................................................................. 47 Figure 19 The Top view of block FF .................................................................................................................... 48 Figure 20 The Left side view of block FF .............. ............. ............. ............. .............. ............. ............ .............. ... 48 Figure 21 Overview and the front view direction of block EE ............................................................................. 49 Figure 22 Block EE Front view............... .............. ............. ............. ............. .............. ............. ............ .............. ... 50 Figure 23 The Top view for block EE ............. .............. ............. ............ .............. ............. ............ .............. .......... 50 Figure 24 The Back view of block EE .................................................................................................................. 51 Figure 25 Overview and direction of front view for block DD ............................................................................. 52 Figure 26 Block DD Front view ........... .............. ............ .............. ............. ............ .............. ............. .............. ....... 52 Figure 27 The Top view of block DD ................................................................................................................... 53 Figure 28 The back view f block DD .................................................................................................................... 53 Figure 29 Overview and direction of front view for block CC ............................................................................. 54 Figure 30 Block CC Front view ............. ............ .............. ............. ............ .............. ............. .............. ............ ...... 54 Figure 31 The Top view of block CC ................................................................................................................... 55 Figure 32 The Back view of block CC ............ .............. ............. ............ .............. ............. ............ .............. .......... 55 Figure 33 Overview and direction of the front view for block BB ....................................................................... 56 Figure 34 Block BB Front view ............................................................................................................................ 56 Figure 35 The Top view of block BB ................................................................................................................... 57 Figure 36 The Back view of block BB ............ .............. ............. ............ .............. ............. ............ .............. .......... 57 Figure 37 Overview and direction of front view for block AA ............................................................................. 58 Figure 38 Block AA Front view ........... .............. ............ .............. ............. ............ .............. ............. .............. ....... 58 Figure 39 The Top view of block AA ................................................................................................................... 59 Figure 40 The Back view of block AA ................................................................................................................. 59 Figure 41 Energy distribution for Option A .......................................................................................................... 65 Figure 42 North and south side output loads from biomass boilers ............. .............. ............. ............ .............. ... 69 Figure 43 SWH output from the Lots Road site ............ ............. ............ .............. ............. .............. ............ .......... 70 Figure 44 PV output from the Lots Road site ....................................................................................................... 71 Figure45 North side energy centre and buildings ................................................................................................. 75 Figure 46 South side energy centre and buildings ................................................................................................ 76 Figure 47 Schematics over the south energy centre. ............................................................................................. 78 Figure 48 Schematics over the north energy centre .............................................................................................. 79 Figure 49 Block GG electrical connection ............................................................................................................ 83 Figure 50 Thermal connection to block JJ ............................................................................................................ 84 Figure 51 A residential unit heat and power connection ....................................................................................... 85
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List of Tables
Table 1 Energy system matrix ............ ............. .............. ............. ............ .............. ............. .............. ............ .......... 26 Table 2 Carbon reduction matrix .......................................................................................................................... 27 Table 3 Cost matrix ............................................................................................................................................... 28 Table 4 Advantages of Option A........................................................................................................................... 63 Table 5 Disadvantages of Option A ...................................................................................................................... 63
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[21] Earth Energy [Home page on the Internet], Earth Energy [Updated 2006, Cited 05-06-2007], Available
from: http://www.earthenergy.co.uk/case_studies/social_housing.php
[22]Sustainable Development Commission [Home page on Internet], SDC [Cited 09-07-2007], Available from:
http://www.sd-
commission.org.uk/publications/downloads/Bronllys%20Hospital%20Solar%20Energy%20Project.pdf
[23] Energy Savings Trust [Home page on the Internet], Energy Savings Trust [Updated 2008, Cited 21-07-
2007], Available from:
http://www.energysavingtrust.org.uk/northern_ireland_advice_centre/case_studies/domestic_solar_water_heatin
g_case_studies
[24] Maunsell F, London Renewables Integrating renewable energy into new developments: Toolkit for
Planners, developers and consultants, London, Greater London Authority, 2004, p 35, ISBN:1852616601
[25] Proven Energy, Health and Safety Information for Installation of Proven Wind Turbines in Public Areas,
Scotland, Proven Energy, 2003
[26] Sustainable Development Commission [Home page on Internet], SDC [Cited 09-07-2007], Available from:
http://www.sd-commission.org.uk/communitiessummit/show_case_study.php/00177.html
[27] ] BRE, SAP 2005:The Government´s Standard Assessment Procedure for Energy Rating of Dwellings,
Watford, DEFRA, 2005, p.67
[28] The Ashden Award For Sustainable Energy [Home page on Internet], [Updated 2008, Cited 09-07-2007],
Available from: http://www.ashdenawards.org/winners/barnsley
[29] Hoare Lea Consulting [Verbal Source], Hoare Lea Consulting, Bristol, 2007
[30] ] Action energy, Good Practise Guide Combined heat and power in buildings, England, Carbon Trust,
2004, p.06
[31] Alberta Centre for Injury Control & Research [Home page on Internet], Alberta Centre for Injury Control &
Research [Updated 01-05-2007, Cited 20-05-2007], Available from:http://www.acicr.ualberta.ca/documents/HotWater2003PositionStatement.pdf
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Appendix A Energy Systems & Sustainable Design Systems
A1 Energy systems
This section reviews in greater detail varying energy systems. It includes Biomass,
CHP, Biomass CHP, GSH, PV, SWH and Wind power.
In this section there is also an evaluation to find the most suitable CHP method for
urban areas, together with a description and evaluation of energy for waste
possibilities.
A1.1 Biomass
Biomass is burned as fuel to generate energy there are different types such as wood
chips and willow. Biomass is derived from bio organic material and is a carbonneutral energy source this means that the net emission is zero. Biomass absorbs
carbon dioxide through photosynthesis and that is then the only carbon dioxide
emissions released back into to the atmosphere when it is used as fuel.
The biomass fuel is divided into dry and wet fuel types. Dry fuel is solid fuel from for
example forestry, woodchip or energy grass. Wet fuel is gas or liquids. Wet fuel is for
example methane extracted from anaerobic digestion.
Figure 1 Carbon dioxide cycle
Photosynthesis is the process plants and trees use to transform photon energy to
chemical energy. [1]
Energy plant
Biomass
Carbon
Dioxide
Carbon dioxide is being absorbed
through Photosynthesis
Biomass is being harvested and
transported to the energy plant
Carbon dioxide is being
released back into the
atmosphere from combustion.
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Dry fuel types and energy generation
Dry fuel is solid biomass fuel and can be grown for fuel generation or gathered
forestry residue. Here is a brief explanation of some dry biomass fuel types.
After the dry fuel section is a brief explanation of the three methods to generateenergy. They are conventional combustion, gasification and pyrolysis.
Dry Fuel types
Using biomass fuel for domestic and commercial use is widely known in countries
like Sweden, Denmark or North America. Biomass is also utilized for heating homes
in developing countries where burning wood in a fireplace is sometimes the only
available option. In the UK biomass is not a common option to heat and power
homes. UK has one straw fired power plant to generate electricity [2].
Material from forestry or timber residues such as sawdust and wood shavings is used
for biomass fuel. Forestry production in Europe is mainly for timber and pulp. This
leaves surplus material that can be utilized for energy generation. This is favourable
because the material utilized as fuel would otherwise go to waste.
Biomass is also grown with the intention to be utilized as fuel. One method is to use
small tree harvesting. Small trees are then grown and after harvesting the trees are
chopped up into, wood chips, biomass fuel. The advantage is that after harvesting re-
plantation can be done immediately.
The purpose of growing biomass fuel is to achieve a more reliable and available fuelsource than just forestry residue. Problems with residue material are its unreliable
density and calorific value (energy per kilo). This should be high to get a high energy
output. Another factor is the moister content in biomass if it is to high combustion is
hard to achieve.
Energy Crops are mainly willow and it is grown as biomass fuel as mentioned. The
willow is grown as Short Rotation Coppice (SRC). SRC is a known biomass source in
the UK and is well proven in Scandinavia. It has a growing cycle between 2-4 years
before harvesting and is relatively inexpensive to plant. Another advantage is that
after using the land for SRC it has a short recovery period before it can be reused.
An unproven energy crop in the UK with promising prospects is Miscanths.Miscanths is also known as elephant grass. The grass can be grown specifically for
biomass fuel and has a growing cycle of one year before harvesting. Disadvantage of
Miscanthus is that it is difficult to reuse the land for another purpose. [3] [4]
Wood pellets are a form of biomass fuel that can be formed from forestry residue.
Pellets are dryer and have a higher calorific value than wood chips, however they are
more expensive due to the more intensive manufacturing process.
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In 1994 in the UK the primary forestry user was in sawmills. A by product from
sawmills is sawdust and it can be turned into pellets. Advantages of pellets are that
they are dust free and easy to transport because they are compact.
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Energy generation
There are mainly three different methods of converting dry biomass fuel to energy.
The most common one is direct combustion. Through direct combustion the biomass
fuel is exposed to heat making it combust and releasing thermal energy.
Direct combustion
This could be directly in a stove or fire place for domestic heating. It could also be in
an energy plant. Different configurations of energy plants are heating, electricity or
CHP plants.
Direct combustion has the reaction:
CxHyOz+(x+y/4-z/2)O2 => xCO2 + (y/2)H2O Equation (65)
This is the overall reaction for a fuel of mean composition CxHyOz
It is the energy that is being realised during this combustion that can be used for
thermal power or/and electricity. [4]
Figure 2 Thermal energy, biomass fuel to a water circuit [5]
The thermal energy is generated from fuel being burnt in a combustion chamber. The
hot gases are lead to a heat exchanger where the thermal energy is transferred to water
to provide space heating and hot water. Another configuration is to circulate a fluid
Combustion Chamber
Boiler
Hot gas
To chimney
To chimney
Cold gas
FuelAirAir
Fuel
Heatexchanger
Heat
exchanger
Cold Fluid
Hot fluid
Cold water
Hot water
Cold water
Hot water
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through the boiler to absorb heat and then to a heat exchanger where it releases the
thermal energy to provide space heating and hot water.
Gasification and Pyrolysis
The other two methods to generate thermal energy for dry biomass fuel are throughgasification and pyrolysis.
The gasification process generally takes place in a temperature range between 800 to
1200 °C. Biomass fuel is heated up under a low oxygen condition to reach
gasification, a state of incomplete combustion. A gas called Syngas is created in a
thermal process with oxygen. The product from the gasification process will be a
mixture of hydrogen, carbon monoxide and waste products such as tar and ash
depending on process. The gas can be used in gas engines and turbines. To ensure
efficient use gas cleaning is essential.
The pyrolysis process generally takes place in a temperature range between 400 to
700 °C. The process is very similar to gasification but uses zero oxygen. The product
fuels from the pyrolysis are gas (also Syngas) or liquid fuel depending on the
manufacturing process. The gas can be used as fuel in gas engines or turbines and the
liquid can be used as liquid biofuel. Liquid fuel is more controllable and easier to
handle so Pyrolysis has a promising future for transportation and storage. To ensure
efficient use cleaning of the fuel is essential. [6] [7]
Infrastructure
Biomass fuel has to be bought it is not like the renewable energies of photovoltaic or
wind power. Harvesting photon energy from the sun and kinetic energy in the wind,for PV and wind power, are available and can be harvested cost free on site. This
means biomass will have a longer payback time and it is shown in the payback
calculation section in appendix.
The price for biomass fuel is usually referred to as the same as fossil fuel. The
important factor is to look at the calorific value. It is the value that determines how
much energy can be extracted from the fuel. For biomass dry raw bio fuel it is
approximately 20 MJ/kg (LHV) this is comparable to mid quality coal. The calorific
quality differs if it is dried or freshly harvested. Freshly harvested wood biomass has
usually a moister content of 50% and this lowers the caloric value to 8 MJ/kg (LHV)
[8]. As mentioned the calorific value is related to moisture content. The calorific
value also varies with the kind of biomass material that is being utilized.
Pellets have a higher calorific value then other biomass fuels and this is one of the
reasons to why pellets are more expensive. From a background document for pellets
the calorific value is estimated to 4.7 kWh/kg which is 16.9 MJ/kg. (LHV) [9].
There are two measures of calorific value. Lower heating value (LHV) and Higher
heating value (HHV). LHV is the Net calorific value. It measures the heat released on
the basis that the water remains in the vapour phase.
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HHV is the Gross calorific value. It measures the heat released when the fuel is burnt
and the water has condensed out of the combustion gases as a liquid.
Here is a comparison of the calorific HHV for different fuels [10].
Calorific value table
Fuel HHV MJ/kgEthanol 30
methanol 23
General purpose coal 32-42
Diesel fuel 46
Gas oil 46
Wood 15% water(Biomass) 16
North Sea Natural Gas 39Table 1 Showing calorific value of different fuels
In the table above biomass, with 15% water content, has a higher heating value of
16MJ/kg and natural gas has a value of 39MJ/kg. A larger amount of fuel is therefore
needed for biomass then natural gas to achieve the same energy output.
Fuel storage for biomass has the advantage from other renewable energies that it can
easily be stored in a storage room or a basement for later use. This is also a
disadvantage since it needs storage space and is not harvested and directly converted
to useful energy. For photovoltaic the photon energy is converted to energy directly
through the semiconductor. Another disadvantage is that since the calorific value isrelatively low for biomass. Biomass storage requires a larger space then for example
diesel fuel.
In the London toolkit there is a case study of King’s Mead Primary School, it has a
10m3
storage bunker. Providing fuel to a 50 kW biomass boiler, for this relatively
small project, fuel only needs to be delivered 3 to 4 times a year [11].
Biomass is a renewable energy source and, when transport emissions are not
considered, is not adding carbon dioxide to the atmosphere. It is important to consider
travelling emission because biomass fuel sometimes has to travel large distances
between harvesting and end user. From for example the forest to an energy centre
located in an urban area, this should be taken into consideration when choosing
biomass for energy generation. The carbon emission emitted to the atmosphere is
therefore not only the carbon emission emitted by the bio mass fuel when utilized and
subtracting the absorbed emissions through photosynthesis. It is also the emissions
from travelling to the end destination. The most environmentally friendly transport
alternative for biomass is considered to be by ship or boat [12].
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Wet fuel
Wet bio fuel can be created through a digestion process from bio degradable waste
such as garden residue, certain wood waste and agriculture residue.
Anaerobic Digestion and Landfill
Anaerobic digestion (AD) converts bio waste that otherwise would be difficult to
utilize such as agriculture waste and organic waste.
The AD method digests bio waste to produce biogas (mostly methane) in the absence
of oxygen.
Biogas from anaerobic digestion can be used in a steam turbine because of the
separation from the heat source and turbine. Bio gas is burnt in the boiler and water
(steam) is used as the medium that absorbs the thermal energy and drives the turbine.The biogas can also be cleaned and used in gas engines or gas turbines.
The landfill method extracts gas created from digestion, similar to AD, of bio waste.
The gas (mostly Methane) can then be burnt for energy generation
Land fill gas can effectively be used in a steam turbine. Land fill gas (LFG) when
cleaned can also be used in gas engines and multi fuel engines. Multi fuel engines are
engines utilizing different fuels for example landfill gas mixed with diesel. [13] [14]
How to deliver biomass fuel to the Lots Road site and fuel types such as bio diesel or
rapeseed oil have because of limitation in time not been investigated in this report.
Advantages
• Renewable technology
• Considered carbon neutral
• Well known technology
Disadvantage
• Fuel transport
• Fuel storage
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A1.2 Combined Heat and Power
Combined heat and power (CHP) generates electricity and thermal energy. CHP is an
efficient method to provide heat and power for residential blocks, hospitals or
industries.
It can also be used in smaller scale as micro CHP, providing heat and power to
specific buildings.
It is the heat recovery process from the electricity generation that makes CHP
efficient. It is therefore important to size the CHP after how much thermal energy that
is being produced in order to be energy efficient.
Due to the avoidance of transmission losses there is approximately a 30% reduction in
energy usage for CHP. From utilizing CHP the transmission losses from delivering
electricity through the grid and thermal energy losses from a distant energy plant can
be avoided. [1]
Natural gas fired CHP can be used to achieve energy savings, compared to burning
gas for heating and electricity delivered from the grid, when providing both heat and
power. A reduction in carbon dioxide emissions of 30% [1] is possible. Different CHP
technologies are investigated in this section.
Renewable energy fuelled CHP exist but the technology is still new in the UK.
Biomass fuelled CHP will probably in the future be a more available option. Biomass
CHP is investigated in the end of this section.
CHP can be used in connection with the domestic grid where any redundant
electricity generated from the CHP scheme is sold back to the grid. The grid can alsobe used as backup if the scheme has an electrical shortage.
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Below is a comparison between a conventional network and community scheme CHP
[2].
Figure 3 Comparison between CHP and conventional network
The figure above is showing fuel input and how large the losses are through energy
generation. The CHP plant has a total energy efficiency of 80% where 45 units of heat
is generated when 35 units of electricity is created. For the conventional network the
total efficiency is 57%. This is equivalent to a 23% more energy efficient CHP
scheme compared to a conventional network. The conventional network uses a power
plant feeding the grid to get electricity and gas boilers for thermal energy. The CHP
scheme would also result in significant carbon dioxide emission reductions since less
fossil fuel is being used.
Electricity 35% efficiency80 Units of fuel
30 Units ofelectricity
50 Units of losses
Thermal 85% efficiency60 Units of fuel
50 Units of heat
10 Units of losses
Conventional net work
CHP efficiency 80% in total100 Units of fuel
35 Units ofelectricity
45 Units of heat
20 Units of losses
Community CHP
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CHP Technologies
CHP Gas turbine:
Gas turbines have god reliability and high output ranges from 500kW to 250MW. Gasturbines expels a quality exhaust gas which means the gas has a high thermal energy
content that can favourably be utilized in CHP applications. Gas turbine CHP has low
maintenance and a long time between overhaul. Gas turbines can work on natural gas
but also biogas from gasification. They have high efficiency when working on full
load but the efficiency decreases when the load decreases [3]. Therefore if selecting
gas turbine CHP it is important that the turbine will work in optimal, full load,
conditions.
Gas turbine uses the Brayton Cycle. The Brayton cycle simplified is that air is
compressed heated and expanded.
In the gas turbine the air is lead through the inlet where it is compressed and mixed
with fuel then combusted which drives a turbine that is connected to a generator to
produce electricity. The exhaust heat is utilized by passing it trough a heat exchanger.
The thermal energy can then be used for space heating and hot water [4].
Figure 4 Simplified explanation of gas turbine CHP
The figure above shows a simplified, gas turbine, onsite CHP system providing
domestic hot water (DHW), space heating (SH) and electricity for the residents.
AIR
Compression
Combustion
Fuel
Turbine
Exhaust
DHW and SH
Cold Water
DHW and SH
Warm Water
GeneratorElectricity fordomestic use
Heatexchanger
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CHP Steam turbine
The steam turbine uses the Rankine cycle. The Rankine cycle is a thermo dynamic
cycle where a heat source transfers water into high pressure steam.
A boiler generates thermal energy that pressurised water absorbs to create highpressurized super-heated steam. The thermal energy in the steam then drives the
turbine to generate electricity via a generator. The thermal energy left in the steam is
then utilized for thermal applications.
Figure 5 Simplified explanation of steam turbine CHP
The figure above is showing a steam turbine CHP scheme where the boiler generates
hot steam that drives a turbine to generated electricity from the generator. The thermal
energy content left in the steam is then utilized for heating of DHW and SH. This is
by dissipating heat through a heat exchanger. The return heat from the heat exchanger
is then cooled through a condenser and the water is circulated back to repeat the
process [5].
In steam turbines as mentioned fuel is burnt to heat water to create steam. CHP steam
turbines have an advantage since the energy is transferred by hot steam from the
boiler to the turbine and is not directly connected with the turbine. The advantage is
that various types of fuels can be utilized in the boiler. It can for example work onbiogas from landfill.
Steam turbines sizes are available for ranges from 100 kW to 250 MW and are
expected to have a long life time if maintained correctly. Disadvantages for steam
turbines are that they have a long start up time compared to other CHP technologies.
Together with a low power to heat ratio compared to other CHP technologies [6].
It is therefore important when selecting steam turbine CHP that the heat demand is
high compared to the electrical demand.
Fuel
DHW and SH
Cold
DHW and SH
Warm
Heatexchanger
Boiler
Turbine
GeneratorElectricity for
Domestic usage
Condenser
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CHP Gas engine
CHP can use a combustion engine to generator electricity and the exhaust heat to
generate thermal energy. There are two types the spark engine (SI) and the
compression engine (CI). The main one that uses natural gas is the SI engine. The CI
engine can work on for example dual fuel. This is for example diesel mixed withbiogas.
The engine uses the Otto cycle
1, Intake stroke 2, Compression stroke 3, Power stroke 4, Exhaust stroke
An air and fuel mixture is introduced in the cylinder during the intake stroke it is then
compressed during the compression stroke and ignited by a spark plug for an SI
engine or through high pressure for the CI engine. After ignition the gases expand
pressing the piston downwards during the power stroke. The exhausts are then
expelled during the exhaust stroke so the process can start over again.
This brief overview below is for a CHP SI combustion engine.
Combustion engines have good efficiency working at different part loads. They are
available at different size from 10 kW to 5 MW and have fast start up time compared
to other CHP technologies. Another advantage for the CHP combustion engines is
also that the combustion engine is reliable. This means they have long life time and
have a low shut down period for maintenance [7].
There are four main sources of exhaust heat that can be recovered from a
reciprocating engine from the exhaust gases, jacket cooling water, lubrication cooling
water and if used, from turbo charger cooling. From this thermal power is recoveredthrough hot water or low pressure steam [8].
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Figure 6 Simplified explanation of gas engine CHP
Figure 6 shows a configuration of a small scale gas engine. It uses the heat from the
exhaust and the engine cooling system to deliver DHW and SH for an onsite CHP
scheme.
Cold water
Hot water
Exhaust heatexchanger
Engine exhaust
gases
Generator
Electricity
Engine heat
exchanger
Engine
exhaustEngine
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CHP matrix
Below is a CHP information matrix it contains available CHP output, CHP
efficiencies and the power to heat ratio.
Table 2 Information from EPA Catalogue of CHP technologies 2002 [9]
Other technologies
For small scale energy generation there is micro CHP. Micro CHP has the advantage
that it’s flexible in meeting varying heat loads and that it can run on different fuel
types.
Another technology is fuel cell CHP but the commercial application for fuel cell CHP
is small and the capital cost is high [10].
Steam turbine Gas engine Gas turbine Micro turbine
Available size 500kW to250MW 100kW to over 5MW 500kW to 40MW 30kW to 350kW
Efficiency 80% 70 to 80% 70 to 75% 65 to 75%
Power to heat ratio 0.1 to 0.3 0.5 to 1 0.5 to 2 0.4 to 0.7
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Biomass CHP
Here is a brief overview of Biomass CHP it is still considered as a new technology
even though it is utilized in countries across Europe.
In the UK biomass is not broadly utilized for domestic heating schemes together withthat CHP have not been well known in the UK for more than the last five to ten years.
A brief investigation were carried out for biomass CHP and from the investigation no
on site biomass CHP plant, delivering heat and power in urban area to residents, were
found. Biomass CHP was utilized as a test plant in Bedzed and there are a few small
scale biomass CHP plants working in the UK for example ECOS millennium centre in
Northern Ireland [12]. From this brief investigation biomass CHP were considered
unavailable early in the project. The best example found on residential onsite biomass
CHP is the Titanic mill in Huddersfield [13] it is being converted into flats and will in
later stages implement a small scale biomass CHP delivering heat and power to
residents.
As mentioned previously in this section steam turbines and gas turbines can be used
with fuel from gasification and pyrolysis. It could also use gas from landfill or
anaerobic digestion. Gasification and pyrolysis is still a new technology to use for
biomass CHP in the UK. Gasification is more widely used for waste processing there
is for example a small scale municipal waste plant in Bristol.
When using solid biomass fuel for CHP, gasification and pyrolysis are favourable
methods compared to conventional combustion. Solid biomass fuels are burnt in a
boiler for steam turbine CHP. Gasification and pyrolysis transform the biomass to
biogas and can therefore be used in a gas turbine or gas engine CHP [10].
Gas turbines or gas engines have a higher power to heat ratio compared to steam
turbines and can therefore generate more electricity.
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CHP Design
CHP can be connected to a building in parallel or in series together with other boilers
to provide the heating load. CHP is recommended to be the lead boiler in order to be
cost effective a rule of thumb is that it should be working 5000 hours per year to be
cost viable.
The sizing for CHP is generally on the thermal base load, i.e. the domestic hot water,
to not waste thermal energy. Another action to prevent heat waste, when
implementing CHP, is to utilize heat storage. It is usually a well insulated water tank
that acts as a heat store when the thermal demand is low. For example if CHP is
utilized for electricity during the day the heat produced can be stored for space
heating at night.
Implementing more CHP will help the UK to reach its CO2 targets. It can result in
more than a 30% reduction in carbon dioxide emissions compared to conventional
heat and power generation [11].
Advantages
• Energy savings compared to conventional energy generation
• Carbon emission savings compared to conventional energy generation
• Produces both heat and power
• Many different technologies to choose from to get a optimal CHP system for
the end user.
Disadvantages
• Renewable fuelled CHP is a very new technology in the UK
• Conventional CHP is not a renewable technology and emits carbon dioxide
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CHP Evaluation
The combined heat and power section are evaluated to find CHP systems suitable for
urban areas.
Steam Turbine CHP Micro turbine CHP Gas turbine CHP Gas engine CHP
Advantages Advantages Advantages Advantages
Long working life Compact size Reliable Well known technology
Broad output Range High thermal output Broad output range
Disadvantages Disadvantages Disadvantages Disadvantages
High Cost Broad output rangePoor efficiency at low
loading High maintenance costSuitable for larger
schemes Low efficiency Noisy
Long start up time high pressure
Low power to heat ratioTable 3 Showing CHP advantages and disadvantages
Micro CHP has limited energy output and lower efficiency then gas turbine and gas
engine CHP. Lower efficiency will mean higher carbon dioxide emissions and a low
energy output can limit micro CHP to smaller sites.
Micro CHP is therefore not seen as a suitable energy system at larger sites. Lots Road
is assumed to be a large site in this report.
Steam turbine CHP has longer start up time and a low power to heat ratio compared to
other CHP methods. It is important to have a fast start up time for the CHP to be able
to provide heat and power without delays to the residents. With a low power to heart
ratio there needs to be large heat storage to not waste energy.
Steam turbine CHP is therefore not seen as a suitable energy system for the Lots
Road site.
Gas turbine CHP is a high pressure process and has poor efficiency at low loading.
The gas turbine CHP if operating at a lower load will raise the carbon dioxide
emissions. Gas turbines are a high pressure process and are considered noisy. This
could be disturbing for residents when using onsite CHP.
Gas turbine CHP is therefore not seen as a suitable energy system for the Lots Road
site.
Gas engine CHP is a well known technology and have a broad output range. It canwork on natural gas and biogas when or if available.
Gas engine CHP is therefore seemed as the most suitable CHP technology to have in
an urban area.
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CHP Selection
The selection is made from the evaluation above.
If CHP is selected for the Lots Road site gas engine CHP will be utilized. It is the
most suitable CHP method for energy generation at urban areas.
The main reasons are:
• Well known technology in the UK
• Have a broad output range
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A1.3 Ground Source Heat Pumps (GSHP)
Ground source heat pumps use the grounds natural thermal conductivity to extract or
dissipate thermal energy. The ground is a favourably heat source since the
temperature in the ground don’t fluctuate much during the year. The temperature does
not change rapidly like the outdoor air which gets warm in the summer and cold in thewinter.
The GSHP for this report is considered to be a reversible heat pump. A reversible heat
pump can be used for heating in winter and cooling in the summer.
It is shown in this report that CO2 emission savings are achievable compared to
conventional natural gas heating. Ground source heat pump emission savings depends
on the heat pumps coefficient of performance (CoP). CoP of 4, means that 4 units of
heat are generated from 1 unit of electricity. The electric heat pumps CoP usually
range from 2.5 to 5 [1].
The electricity is used to lift the temperature to a useful level were it can be utilized in
the building. The type of heat pump discussed in this report is as mentioned an
electrical heat pump. This means that ground source heating is not a renewable energy
source because the pump uses electricity delivered from the grid.
HP Technical Description:
Figure 7 Describing the Heat pump cycle
The heat extracted from the ground is absorbed by the heat carrier fluid in the heat
pump it is then evaporated in the evaporator. The evaporated process uses the thermal
energy from the ground to turn the fluid into a gaseous state.
Compressor
Electrical
motor
Dissipate
Heat
ExpansionValve
Absorbs
Heat
HeatInput
HeatOutput
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The gas is then compressed by an electric driven compressor. This increase the
pressure and temperature of the gas i.e. the electric compressor lifts the temperature to
the wanted output temperature. The gas is then delivered to the condenser where it
dissipates its thermal energy to warm the building.
In the condenser when dissipating its thermal energy the gas condense to a liquidstate. The liquid is then expanded through an expansion valve this lowers its
temperature and pressure. After returning to a low temperature and pressure fluid the
heat pump, refrigeration, cycle can be repeated. [1]
There are two different types of ground source systems it is either a direct or indirect
system. It is called an indirect system because the heat is transferred to the evaporator
via a heat exchanger. In an direct system the ground source pipes are used as the
evaporator [2].
Ground Source heating closed loops
Pipes are buried under ground in a horizontal or vertical position. A fluid in the pipes
is circulated to extract heat from the ground. After extracting heat from the ground the
fluid is lead to the heat pump where it releases its thermal energy. There are open and
closed systems in the closed system the fluid is pumped back through the pipes to
repeat the process while it is dumped in the open system.
Figure 8 Vertical closed system
HP
Building
Ground
CooledWater
WarmedWater
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TrenchHorizontal
Pipe
Horizontal Series Horizontal Parallel
Horizontal Ground Source Heating
Horizontal pipes
Pipes are buried approximately 2 meters under ground in trenches the horizontal pipes
requires a wide surface area compared to vertical pipes. For a large individual house
approximately 100 m2 of area is needed for technical feasibility e.g. to get a sufficient
thermal output. [3]. This is a disadvantage for horizontal systems, when beingimplemented in urban areas, because space if often limited.
Figure 9 Horizontal pipe configurations [4]
For horizontal systems the trench can contain one or several pipes. The pipes can be
connected in series or parallel as shown on the figure above.
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Vertical pipes
Pipes are fitted into the ground in boreholes that is drilled 15 to 150 meter down into
the ground. The depth depends on the heating load and soil type. The heat load is how
much thermal energy the system is set to produce for the end user. Before drilling
boreholes, planning consent from local authorities are needed [5].
The boreholes need to be spaced apart so absorption or dumping of heat is kept
optimal. The recommendation is at least 5 meters apart with preferably 15 meters [5].
The spacing differs depending on the soils ability of temperature recovery. It is the
ability of the soil to return to the normal ground temperature.
Figure 10 Vertical pipe configurations [6]
For vertical systems the borehole contains a U-tube. The pipes can be connected in
series or parallel as shown on the figure above. There can also be more then one U-
tube in a single bore hole.
Bore hole
Vertical Parallel
Vertical Ground Source Heating
Vertical Series
Bore hole
Single U-tube
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Slinky Coil
The spiral coil also know as a slinky coil is laid out in a trench with the benefit that it
needs less surface area then for horizontal piping .
The trench length for a heating system is approximately only 30% compared tohorizontal pipes. Even though the trench is shorter the coil length needs to be longer
then to achieve the same thermal output [7].
Figure 11 Spiral coil design
Spiral Coil
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Energy Piles
Energy piles work as a closed heat pump system. The Energy pile is placed in the
foundation of the building where it provides heating or cooling to the building. The
Piles uses the grounds natural thermal conductivity to extract or dissipate thermal
energy. Piles are usually embedded in concrete which acts as good energy transfermedium. A fluid is used to absorb or release heat in the tubing of the piles. The fluid
is pumped around the system and releases its thermal energy to the heat pump. The
typical configuration for energy piles is to use a reversible heat pump. A reversible
heat pump is used for heating in the winter and cooling in the summer [8].
There are several different types of configurations were the energy system is
connected to the foundation. Below are energy piles and energy slabs.
An energy pile configuration were the tubing is attached on the inside of a steel cage
is shown below.
Figure 12 Energy pile configuration [9]
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An energy slabs configuration were the tubing is laid out horizontally in the
foundation is shown below.
Figure 13 Energy slab configuration [9]
Ground Loop Open Systems
A borehole is drilled down to the water level. Water is then extracted from an aquifer
(layer of water-bearing rock) or from the ground water. It is pumped through a heat
exchanger where it dissipates its thermal energy and is then discharged into another
drilled borehole. This can be done for both heating and cooling.
System description
Figure 14 Open loop cooling system
Cold Warm
HeatPump
Filter
WarmCold
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Surface Water System
It works with the same principle as an open loop borehole system but uses a different
water source. Here an open source such as a river is used for heating or cooling by
extracting warm or cold water from a deep point in the river. It is then pumped
through a heat exchanger where it dissipates its thermal energy and is then discharged
back to the source. The returning water is discharged close to the surface of the river.
Figure 15 Surface water cooling system
Other open loop systems are for example a ground air system. Then air is heated bydrawing air through an underground matrix to absorb thermal energy from the ground
below the building. It is then passed through a heat pump realising its thermal energy.
Disadvantages for an open loops system is that it requires regular maintenance to
make sure filters do not collect to much debris and that pumps are more open to
erosion then in a closed system. [10]
River
Cold
Filter
Heat
Pump
Warm
Warm
Cold
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GSH design
Calculations from www.canren.gc.ca [11]
In order to estimate the length of the pipe needed for ground source heating these
simplified equations can be used.
Vertical pipe length (m) heating
L=0.05506 x Ea/(Tg-Tlmin) Equation(66) Ea = Energy absorbed from the ground (MJ)
Ea= Eh x EFLh x ((CoP-1)/CoP Equation(67)
Eh = Peak heat Load (MJ)
EFLh = Full load hours of the system (Hours)
Tg = Ground temperature (°C)
Tlmin = Minimum entering liquid temperature (°C)
Horizontal pipe length (m) estimation for heating
L = [Eh x ((CoP-1)/CoP) x (51 + Rs x PLFh)] / (Tg-Tlmin) Equation(68) Eh =Peak heat Load (MJ)
Rs = Soil/Field resistance (m2°C/kW)
PLFh = Design month, part load factor
Tg = Ground temperature (°C)
Tlmin = Minimum entering liquid temperature (°C)
CoP = coefficient of performance for the heat pump
A typical solid field resistance value [12] is 742 (m2°C/kW)
This is for medium soil conditions.
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A simplified equation from BSRIA [13] for the mean ground temperature is:
tm = to + 0.02 x h(°C) Equation(68)
tm is the mean temperature in the ground
h is the dept below the surface (m)
to is the annual mean air temperature
The equation to calculate the CoP from BSRIA [14] is
CoP = (Heat output (kWthermal)) / (Electricity input (kWelectricity)) Equation(69)
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The figure below shows how the coefficient of performance for a heat pump changes
depending on condensation (output) temperature. This is for the heat pump when the
source temperature is kept at zero degrees. The curves in the figure are measured heat
pump efficiency curves except for the top theoretical curve. [15]
Figure 16 CoP changing with the condensation temperature. [15]
In order to achieve a high CoP for the heat pump it is important to have a small gap
between the condensation (output) and evaporation (source) temperature. This means
that for heating the ground source should be as warm as possible while thedistribution temperature to the building should be as low as possible. This is to
minimise the electrical input for heating.
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The Low Temperature Hot Water (LTHW) from the ground source heating system
can be used as under floor heating for space heating or as a pre heater for the domestic
hot water.
The heat pump efficiency is lowered for higher temperature outputs such as for
domestic hot water. This is because higher output temperatures require a higher
electricity input to lift the temperature. The temperature if used for DHW needs to beraised over 60°C to minimize the risk for legionella [16].
Advantages:
• The ground is a large heat sink and the temperature is fairly constant over the
year.
• It lowers the carbon foot print compared to conventional heating, heating with
fossil fuel.
Disadvantages:
• Large area needed for horizontal piping
• Needs planning consent from local authorities
• Needs soil type examination to determine system performance
• Electric heat pumps is not a zero carbon emission source
• Heat pump efficiency, the (CoP) needs to be high for high energy savings.
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A1.4 Solar Water Heating (SWH)
A solar collector is used to convert the photon energy from the radiating sun into
thermal energy. There are different variations of collectors in this section the flat plate
collector and the evacuated tube collector will be explained.
Technical description flat plate collector
The sun heats up water contained in a flat plate collector and uses both direct
radiation and diffuse radiation for solar water heating.
Figure 17 showing a flat plate collector
Flat plate collector configuration: [ 2]
1 Frame for collector
2 Glazing (Glass plate)
3 Flow tubes
4 Absorption plate
5Insulation
6 Back frame (support)
7 Inlet
8 outlet
Solar arrays hit the flat plate collector and passes through the glazing the photon
energy in the arrays are then absorbed by an absorption plate. The absorption plate
transfers the energy through convection to liquid in the pipes which are well insulated
to limit heat losses. The liquid enters through the inlet to the flow tubes, absorbs
1
23
4
5
3
6
7
8
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energy and exit through the outlet to a heat exchanger so it can be utilized to heat
domestic hot water. [5]
Technical description Evacuated tube collector (ETC)
General configuration of an ETC is a transparent outer tube with an inner black
painted metal absorption tube. Between the two tubes the air has been extracted tocreate a vacuum this is to stop convection of heat to the outer shell after the
absorption tube has absorbed energy. [3]
Figure 18 Cross section tube Figure 19 ETC
ETC configuration: [3][4]
1 outer glass shell
2 inner glass shell
3 Vacuum
4 absorption layer
5 copper sheet
6 inlet fluid
7 outlet fluid
8 inlet from manifold
9 outlet from manifold
10 manifold
3
42
1
5
67
1
28
9
10
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There is also a reflective layer in the ETC configuration it is not shown in the figure
but it helps to reflect the energy onto the absorption tubes. [3]
The heat transfer fluid enters through the inlet to the manifold and is distributed to the
flow tubes. The fluid then absorbs thermal energy through convection and exit
through the outlet to a heat exchanger. The thermal energy is then utilized to heat
domestic hot water similar to the flat plate collector.
The preferable collector has a high absorption factor with low heat losses. This is
achieved by a thin layer of absorption (black paint) material that has a high absorption
rate. The materials of the plate and the tubes are generally metal such as stainless
steel, aluminium or copper. Stainless steel collector plates have an advantage since
they are not affected to oxygen environments, corrosion, as other metals. [5]
The tubes that contain the heat carrier fluid needs to be well integrated with the
absorption plate to achieve a high U-value of approximately (5700 W/(m2K). This is
one of the most important factors for a high efficiency collector according to Ashrea
application handbook [5]. The high U-value enables the tubes to absorb thermal
energy efficiently from the absorption plate.
Another important factor is the glazing material. Glass transmits around 90% of the
incoming radiation but is not transparent to wave lengths in the IR spectrum (heat
radiation). This means the glazing traps the heat trying to escape from the absorption
plate after the photon energy has been converted to thermal energy.
The strength and isolation of the glazing material can be enhanced by using double
layers of glass. [6]
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SWH simplified system description
Figure 20 Showing a combi boiler [112(8)]. Note: SH stands for Space Heating.
Cold water enters in through the tank and is heated from the SWH system via a coil
heat exchanger. The coil heat exchanger is generally placed at the bottom of the tank
and acts as a pre heater to the boiler system. The boiler brings the water to a sufficient
temperature, over 60 °C for DHW, because of the risk of legionella.
The advantage with SWH system is that during the summer month the SWH system
can deliver most of the hot water demand to the building. The boilers can then acts as
backup [7].
Solar water heating can be used for space heating (SH) but is mostly used for
domestic hot water (DHW). In a combi-boiler as shown in figure 4 there is dualstorage space so the whole tank can be used for storage of thermal energy from the
solar water heating system if the boiler is switched off.
The fluid in the systems is circulated by an electrical pump, which can be powered by
photovoltaic, or by natural convection (no pump) to get a renewable energy system
[7].
DHW
SH
CombiBoiler
Boiler
S u n l i g h t
Inlet
Outlet
Heat
Exchangers
S W H P a n e l
Cold Water
Warm Water
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Efficiency
The energy contribution to domestic hot water is given by the equation.
Qs=S x Zpanel x Aap x η0 x UF x f(a1 / η0) x f(Veff x Vd) Equation(69)
The equation is from SAP 2005 [8]
Explanation to the variables:
Qs: Solar input available from the system (after losses), kWh/year
S: Total solar radiation on collector. Solar radiation is shown in table 17
Tilt H-V
Direction Horizontal 30degrees 45degrees 60degrees Vertical
South 933 1042 1023 960 724
SE 933 997 968 900 684
SW 933 997 968 900 684
E 933 ------------- ------------- ------------ ----------
W 933 ----------- ----------- --------- --------Table 4 Showing average kWh/m2 and changes with tilt and direction
The directions to the north are excluded because of the low energy efficiency from the
collector when facing north. The output for the east and west direction are also
excluded in the table when the SWH panel are tilted because it has a low energy
efficiency.
Zpanel: The shadowing factor for the panel is shown in table 18.
Shadowing factor
Percentage of
panel shaded %
More then 80% 0.5
Between 60 and
80%
0.65
Between 20 and
60%
0.8
Less then 20% 1.0Table 5 Showing the shadowing factor for SWH
Aap: Aperture area (m2) of the collector is the area that can absorb radiation. It differs
from the gross area (Agross) of the collector which is the total area.
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η0: Zero-loss collector efficiency, which depends on the transmittance of the glazing
and the absorption of the black paint. It also depends on the temperature difference
between atmosphere and absorber plate and a heat loss coefficient.
Note: The general expression η for collector efficiency can be seen in Ashrea
application hand book [9]
UF: Utilisation factor
a1: Linear heat loss coefficient
Table 6 shows numbers from SAP to calculate expected energy output for an SWH
system.
Collector type η0: a1: Ratio Aap:Agross
Evacuated
tube
0.6 3 0.72
Flat plate
collector
0.75 6 0.90
Table 6 Showing collector parameters
f(a1 / η0): Collector performance factor
f(a1 / η0) = 0.78–0.034*( a1 / η0) +0.0006(a1 / η0)2
Equation(70)
f(Veff *Vd): Solar storage factor
f(Veff *Vd)=1.0+0.2ln( Veff /Vd) Equation(71)
Veff : Effective solar storage volume in litres
Vd: Daily hot water demand in litres
SWH design
SWH panels should preferably be placed on an elevated angled roof from east to west
facing south. The roof should have an inclination angle between 10-60 degrees to be
effective. Another key point to get efficient use of SWH systems is to ensure that it is
not shadowed at any point during the day. Shadowing usually occurs from trees or
closely located buildings. Shadowing prevents direct radiation on the SWH system
and therefore lowers the efficiency. [10]
SWH systems needs frost protection if it has to endure the cold temperatures achieved
in the UK. The Solar water heating systems do not have a reliable winter performance
and there needs to be a separate system to provide heating during the winter months.
The time limitation of the report has denied a thorough investigation on SWH winter
performance.
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Flat plate collectors are often utilized for SWH systems in domestic homes because it
has a lower capital cost then evacuated tube collectors. The advantage for the
evacuated tube collector is that it has a better winter performance [11]. Approval from
authorities needs to be achieved for listed houses before placing a SWH panel on the
roof.
Advantages
• Well know technology
• Delivers zero carbon emission thermal energy
• Work well together with other energy systems
Disadvantages
• Needs to be uncovered at all time
• Needs to be angled to be efficient
• Winter performance, SWH systems needs backup to supply the yearly DHW
demand.
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A1.5 Photovoltaic
The name photovoltaic can be translated to light electricity. The photovoltaic (PV)
panel do as the name implies convert solar energy to electricity. There are over
thousand PV systems delivering electricity in the UK [1].
Technical description
Sunlight hits a photovoltaic panel that consist of semiconductor cells. Semiconductors
produce direct current (DC) in a process of absorbing photons. Photons carry energy
particles from the sun.
The release of energy when photons are absorbed excites electrons. An excited
electron can reach a free state. This means it is free to travel and this creates
electricity. The photons that hits the PV module has different amount of stored energy
and wave lengths. This is important since the photons being absorbed by the
semiconductor depends on the band gap.
The band gap of the semi conductor is the difference of energy (measured in electron
voltage eV) required for an electron to travel from the bound state to a free state.
Semiconductors with high band gap only absorb photons with high energy content
and photons with lower energy content will be ignored. When a low band gap is used
it absorbs more energy but this result in a weaker electromagnetic field compared to a
high band gap semiconductor.
The electromagnetic field is a force that is measured in voltage (V). The
electromagnetic field makes the free electrons travel from the negative to the positive
charged side of the PV panel. It is important to optimize the band gap (Strength in theelectromagnetic field to band gap) to achieve an energy efficient semiconductor. For a
single cell material an efficient band gap is approximately 1.4 eV (electron Volt). [2]
Materials
The performance for different semiconductor materials are depending on there
absorption coefficient and the band gap. The absorption coefficient is a coefficient for
how long the photon has to travels before being absorbed in the semiconductor.
The most common materials used for semiconductors in PV are Silicon as crystalline,
amorphous or multi-crystalline material.
Poly-crystalline materials and single crystalline materials are produced as thin film to
be used as semiconductors in PV panels. Different types of poly-crystalline materials
are silicon, copper indium diselenide (CIS) or cadmium telluride.
The single crystalline materials are for example materials such as gallium arsenide.
These materials provide high efficiency solar cells. [3]
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Photovoltaic Cell
PV cells are generally built of different layers which are shown in the figure below.
Figure 21 PV panel configuration
PV layers [8]
1 Cover Glass
2 Transparent adhesive
3 antireflective coating
4 Front contact
5 Negative semi conductor
6 Positive semi conductor
7 Back contact
8 Substrate
Figure 77 illustrates a semiconductor with a positive and negative layer. The positive
and negative layer is achieved by doping the semiconductor to ensure instability. The
negative layers are over charged with electrons which mean it has electrons that don’thave a space to fill and the positive layers lacks electrons and therefore have available
spaces.
How the semiconductor works is that electrons cross over from the negative to the
positive side and fill an empty space. This then forms a barrier (an electromagnetic
field) between the layers. Then an alternative route between the positive and negative
side is introduced so the electrons can travel and be utilized for electricity. [9]
12 3
4
56
7
8
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Figure 22 negative and positive semiconductor layers
Manufacturing
The conventional process for manufacturing semiconductor cells is a high energy
process the cells are sawn out on wafers from silicon ingots. To lower costs new
manufacturing processes are using as little energy as possible. The manufacturing
process is that a thin layer of semiconductor material is depositioned on inexpensive
substrate. [10]
As photovoltaic only produces electricity when it is sunny it may be required to store
the electrical energy. There are different ways to store the energy. Deep cycle
batteries discharge a small amount of energy over a long period of time. They can be
charged in the day from sunlight and deliver electricity during the night when there is
no sunlight. Disadvantages for batteries are that they need to be exchanged and
maintained on regular basis. Another option is to use the electric grid. This means all
excess energy is sold to the grid and electricity is bought when PV electricity is not
available. Exchanging energy with the grid tends to be more expensive than storing it
onsite [11].
Electromagnetic field
Load
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Figure 23 Simple schematic of PV [11].
Balance of the system (BOS):
BOS are the essential parts that need to be connected to the PV module to achieve
energy generation in a building. [12] The module is usually put in a steel frame to be
assembled on the roof. Steel is efficient conductor material so the frame can be used
as an electrical contact as well as structural support. An inverter has to be connected
to invert the DC to AC and for electrical protection ground equipment needs to be
installed. Batteries are installed for storage if there is no connection to the grid. PV
also needs a charge controller that makes sure that if batteries are used they do not
overcharge or get drained. This ensures battery duration. The charge controller also
makes sure correct voltage and current is delivered to the end user. [13]
There are efficiency losses in the BOS of around 20%. PV also loses efficiency with
increasing temperature. Therefore two correction factors are used L=0.8 (BOS loss)
K= 0.9 (Temp loss). [14]
The equation to calculate the annual out put of the panel then comes to [15]
Ew= Rθ*esc*A*K*L Equation(72)
Explanation to variables:
Ew: The annual energy output from the panel
Rθ: The annual radiation absorbed by the panel depending on tilt and direction.
esc: Efficiency of the semiconductor
A: Area of the panel
SUN LIGHT
CHARGE CONTROLL
DCBATTERY
ACINVERTER
Only if necessary
CHARGE CONTROL
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K: Efficiency loss with increasing temperature
L: Efficiency losses in the BOS
Efficiency
Photovoltaic works all over the UK and the panels can be integrated to the roof design
to look like regular roof tiles. It can also be used to cover the façade of a building.
Estimated energy produced is around 750 KWh/year for 1 kilowatt peak (kWp) of
panel. Kilowatt peak is the peak amount of energy, in full sunlight, produced from the
panel. 750 kWh per year is approximately 45 to 50% of the electricity demand for a 2
bedroom flat of 4 people according to the London Toolkit. Typically peak energy
from photovoltaic (8-12 % Poly-crystalline Silicon) is 100 Watt per m2
of panel. For a
domestic house the usual panel size is between 9 to 18 m2
to get an output of 1 to 2
kWp. [16]
A series of cells are connected to meet the energy load. To get the most efficient useof PV different factors have to be considered for example house orientation, roof
elevation and the inclination of the roof. A key point to get efficient use of PV is to
ensure that the PV panel is not shadowed at any point during the day. Shadowing
usually occurs from trees or closely located buildings. Shadowing prevents direct
radiation on the PV panel and therefore lowers the efficiency. [19]
Table 21 is showing percentage of annual irradiation absorbed ((kWh/m2)/yr)
regarding tilt (from horizontal to vertical) and orientation.
TILT H to V Orientation % of radiation absorbed
30 degrees South East 95%
30 degrees South West 95%
10 to 55 degrees South Approx 100%
90 degrees V Less then 80%
0 H 90 %Table 7 Data of radiation for London [18]
Irradiation over London is approximately 1059 kWh/m2 /year (2.9 (kWh/m
2)/day),
estimated value from DTI [17].
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Table 20 below shows the efficiency for different semiconductors from the London
toolkit [4].
Type of Semiconductor
Efficiency of the material,
(output / Input)
PV panel area
(for 1kWp) Mono crystalline Silicon 15% efficiency 8 m^2 (1kWp)
Poly-crystalline Silicon 8-12% efficiency 10 m^2 (1kWp)
Amorphous Silicon 4-6% efficiency 20 m^2 (1kWp)
Multiple junction Over 15% efficiency [5]
SemiconductorsTable 8 Semiconductor efficiencies
Multi junction semiconductor is a semiconductor with different layers. The advantage
is that each layer absorbs energy from a specific part of the light spectrum. This
results in a high efficiency semiconductor. [6] Multi junction semiconductors are a
new technology and the efficiency can exceed 15% but are not yet commercially
available in the UK. From the British Photovoltaic Association website, silicon and
single crystalline materials are mentioned as PV cells available on the market [7].
The energy efficiency for a PV panel is measured in the energy output (kWh/yr) from
the panel divided with the energy input (kWh/yr).
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Advantages
• Supplies “green” electricity
• Public awareness
Disadvantages
• Needs to be uncovered (not shaded) at all time.
• Annual sunlight hours in the UK
• Loading capacity for the roof.
• Listed buildings require permission in order to put PV panels on the roof
• Cost efficiency.
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A1.6 Wind Power
The wind has been used as a force for many hundred years. The wind flow rate has a
velocity and when it hits an item it exerts a force. The quantity of this force has to do
with the density of the medium (wind) and the velocity at impact. The other force is
the aerodynamic force and this has to do with equilibrium. If the velocity is decreasedthe pressure will increase to keep equilibrium. This theory is shown below in
Bernoulli’s equation. [1]
P + (1/2 ρV2) = Constant Equation (73)
p= pressure, V=velocity, ρ=density.
When wind turbine blades rotate the kinetic energy in the wind is transferred into
mechanical energy. The mechanical energy can then be used to generate electricity
from a generator.
Aerodynamics
A wind power station uses the same technology as an aircraft to generate lift. The
blades are shaped as an aerofoil to generate lift that exceeds the gravity of the aerofoil
so it moves upwards. On an aircraft wing there are four aerodynamic forces Lift,
Gravity, Thrust and Drag.
An aerofoil is usually rated on a lift to drag ratio. Lift and Drag are design parameters
and gravity is constant at (9.81 m/s2). Drag is depending on the shape of the aerofoil
and has to do with the air flow over the aerofoil exerting a certain friction between the
air and aerofoil surface. This creates turbulence and slows the air down.
The reason for all wings and blades looking very similar is that the design lets the air
to speed up (bulge design) over the wing and is constant (flat design) under the wing.
This creates suction on top of the wing (low pressure) and pressure under the aerofoil
(higher pressure), to get equilibrium. This generates lift which makes the aerofoil
move upwards. [2]
Figure 24 showing an aerofoil.
Gravity
Lift
Drag
Thrust
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Technical description Horizontal Axis Wind Turbines (HAWT)
Different parts in a wind turbine
1. Foundation: The foundation is usually of concrete that are reinforced with
steel rods into the ground [6]
2. Tower: The tower is anchored to the foundation in a vertical direction.
Further up in the air the wind speed are higher so a taller tower means higher
energy input. The material for towers is usually steel.
3. Rotor: The rotor consists of the hub and the blades and is the front of the
nacelle. The blades aerodynamics makes the blades move so the hub rotates.
The blades are connected to the hub at there base. The hub transfers the
rotation to a low speed shaft. The material of the rotor is usually reinforced
plastics. [ 3]
4. Nacelle: the nacelle holds the key components of the wind turbine.
Figure 25 showing a wind turbine [4]
Tower
Rotor
Foundation
Nacelle
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Inside the nacelle:
5. Low speed shaft: The shaft uses mechanical energy transferred from the hub
and transfers it to a high speed shaft through a gear box.
6. Gear box: The gear box transfer the mechanical energy from a low speed shaft
to a high speed shaft to approximately 50 times higher speed output. This isfor larger turbines [3]
7. High speed shaft: The high speed shaft is connected to the generator that
creates electricity. It is also connected to an emergency break
8. Emergency break: The emergency break is generally a mechanical disc break
but can be a hydraulic or electrical break. It is used if emergency braking is
needed for example in high wind speeds over 25 m/s
9. Generator: The generator converts mechanical energy to electricity by
electromagnetic induction. Rotating magnets around a coil inducts a current in
the coil.
10. Cooling: The Generator is usually cooled by fan cooling.
11. Controller: The controller starts and stops the turbine and shuts it down if
necessary. The controller also controls the electrical output and makes sure the
voltage and current output to the grid or domestic housing is correct.
12. Anemometer: The Anemometer measures the wind speed and sends data to the
controller.
13. Yaw motor: The motor powers the yaw drive to get the rotor in favourable
direction.
14. Yaw drive: The yaw drive turns the blades and hub into the wind to get a high
kinetic energy input.
15. Wind Vanes: Measure the wind direction and send data to the yaw drive.[ 5]
[3]
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Figure 26 showing simplified drawings over the Nacelle
The electricity from the generator is sent to a transformer. It transforms the electricityup to between 10000-30000 Volts. This is because there are few losses in sending a
high voltage alternating current (AC) through the grid. The voltage is then
transformed down before being utilized in buildings. The voltage in most European
households is 230 volts and the AC at 50 Hz. [7]
4
15
12
11
7
10
6
8
5
Nacelle
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Wind Power design
Betz law states that only conversion of approximately 59% of the kinetic energy from
the wind flow is possible. If more kinetic energy tries to be exerted to mechanical
energy the wind speed leaving the turbine is to low. Therefore an ideal wind turbine
slows down the wind speed with 2/3 (59% kinetic energy exerted, proved in Betz law(see page 144) of its original velocity.
Generally the larger the rotor diameter the larger the energy output and the higher the
wind speed the higher the kinetic energy. Also at higher altitudes there is less
turbulent wind and higher wind speeds. Therefore designing a tall tower with a large
rotor diameter at a site with high wind speed is preferable.
If the rotor is doubled in size the energy output becomes approximately four times
higher.
Below is a table with numbers from the Danish Wind Industry Association [9]
27 meter 225 kW
40 meter 500 kW
48 meter 750 kW
54 meter 1000 kW
80 meter 2500 kWTable 9 Showing rotor diameters and energy output
The rated energy output for a turbine is the energy it can produce during optimal wind
conditions. . A rule of thumb is that approximately 30% of the rated energy is
delivered from the wind turbine. [10]
Example a 600W turbine delivers approximately 1500kWh/year.
(600W x 356days/yr x 24hr) x 0.3(30%) = 1500kWh/yr Equation(74)
If the wind speed is increased with a factor of 2 the kinetic energy, in the wind,
becomes approximately eight times higher. Below is a table showing wind speeds and
kinetic energy with numbers from the Danish Wind Industry Association [11]
5 m/s 76.2 W/m2
6 m/s 132.3W/m2
7 m/s 210.1W/m2
12 m/s 1058.4 W/m2
14 m/s 1680.7W/m2
Table 10 Kinetic energy in the wind for average wind speeds
This is with an air density of 1.225 kg/m3, dry air at 15 °C.
Note: Kinetic energy should always be calculated from the Weibull distribution and
not with average wind speeds because the real kinetic energy over a year is
considerably higher then the average kinetic energy. Weibull distribution is a,
mathematical statistics technique that is used to get an approximation of the kinetic
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energy per year. It takes into consideration the probability of wind speeds occurring
and the power (kinetic energy) that a specific wind speed carries (The Weibull
distribution function is shown on page 145).
Small turbines usually have rotor diameter of 2 to 9 meter and can favourably be used
in remote location where there is no national grid connection. When located without
grid connection batteries can be used to store electricity [13]. Large turbines can beused for energy generation to communities or as supplier from wind farms (several
wind turbines together in an energy centre) to the national grid.
In urban areas such as London it is difficult to use large scale wind turbines. Small
scale turbines can be used on buildings. Special design small scale turbines can
manage to work efficiently on lower wind speed and in turbulent air around 3.5 m/s.
Normal turbines have to be located away from the building to get undisturbed air and
usually requires wind speeds of 5 to 6m/s. [14] [17]
When planning to place a wind turbine in an urban area the visual impact needs to be
considered. Wind turbines will always stick out and can not be hidden in a basement
or underground as other renewable energies.
An aspect that also needs to be considered is the noise. Wind turbines without
gearbox is considered quieter then “gearbox” turbines. The noise level at the base of a
“none gearbox turbine” has been measured to 60 dB [15].Recommended maximum
level of noise, in a living room, from CIBSE is 30 dB [16].
Other planning issues are placing wind turbines on listed buildings or in conservation
areas. Local authorities also need to be notified to approve the system installation if
the wind turbine is installed to the national grid.
Vertical Axis Wind Turbines (VAWT) is not discussed here they have been
considered but they are not seemed feasible because they have a lower efficiency then
HAWT
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Below is technical data for horizontal axis wind turbines from Proven Engineering
LTD [19]
TYPE (Turbine) 5 m/s 6 m/s 7 m/s
600 W 1,354 kWh/yr 1,948 kWh/yr 2,504 kWh/yr
2,5 kW 4,282 kWh/yr 6,333 kWh/yr 8,403 kWh/yr
6 kW 11,622 kWh/yr 16,900 kWh/yr 21,944 kWh/yr15 kW 29,054 kWh/yr 42,250 kWh/yr 54,860 kWh/yrTable 11 Technical Data: Energy output for turbines at different wind speeds
Below is a wind speed chart over the UK. It is showing the annual mean wind speed
25 meters above ground level.
Figure 27 Annual mean wind speeds for the UK [18]
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Proof Beltz law [8]
The energy the wind turbine generates is the difference in kinetic energy of the air
before and after passing the turbine. Air has the kinetic energy formula
(½)*m*V2
(m=mass V= wind speed). Equation(75a)
The mass can be expressed in
m =ρ*Volume= ρ*A*V (after one second of flow (A=area)) Equation(75b)
According to simplified aerodynamics energy can not be destroyed only changed to
different forms.
The energy extracted from the wind to the turbine is the difference in energy before
and after the turbine. The Power (energy) equation is
P = Power = (½)*m*V2
Equation(75c)
The energy extracted is (Before – After)
(½)*m*ρ*V12
-(½)*m*ρ*V22
Equation(76)
The mass of the air flow is constant before and after the rotor blades according to
conservation of mass.
This becomes
(½)*m*V12- V2)2= P Equation(77)
Where P is the Power extracted
m can be expressed as m after one second of flow as
m= ρ*A(V1+V2)/2 Equation(78)
with (V1+V2)/2 as the average wind speed over the rotor blades
m is then exchanged in the Power equation = >
P= (ρ /4)*(V12
– V22)*(V1+V2)*A Equation(79)
This is the equation for power extracted with A as rotor swept area.
Original kinetic energy equation is
P0 = (ρ /2)*(V1)3A Equation(80)
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The maximum power ratio between extracted power and the original power (P/P0) is
0,59 with the wind speed ratio of 1/3
Weibull distribution
Probability distribution function of wind speeds over a period of time [12] [22]
PW (V0) = 1-exp[-(V0 /C)k ] Equation(81)
Explanation of variables:
PW (V0): Probability function that V is lower than V0
V0: Is the wind speed (limit)
C: Is the scale parameter and can be evaluated from real wind data
K: Is the shape parameter and can also be evaluated from real wind data
To characterise the probability of wind speeds for a turbine, the Rayleigh function is
generally utilizes. The Rayleigh function is the weibull distribution when K=2
Wind turbines advantages and disadvantages
Disadvantages
• Wind Speed
• Wind Turbulence
• Noise
• Height (visibility)
• Cost
Advantages
• Supplies zero carbon emission electricity
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A1.7 Energy From Waste (EFW)
Energy from waste utilizes the stored energy in waste products. There are several
different methods of generating energy from waste such as incineration, digestion,
gasification or pyrolysis.
Incineration generates thermal power through combustion of waste. Gasification and
pyrolysis generates fuel, combustible gas, which can be used for energy generation.
Digestion also generates gas mostly methane and it can also be used as energy fuel.
Generating energy from waste is not a renewable energy source. It emits carbon
dioxide and other greenhouse gases to the atmosphere. The level it emits depends on
the waste content. If the waste is 100% bio waste it can be considered as a renewable
energy source.
Waste
Municipal solid waste (MSW) is collected waste and is mostly household waste. It is
increasing with 3% per year in the UK [1]. The EU directives on MSW are to stop
MSW going to landfill especially biodegradable waste. Biodegradable waste emits
methane and this can be utilized for energy generation. It is important to take care of
the methane gas because it is a greenhouse gas more damaging to the environment
then carbon dioxide [2].
The government has set a waste hierarchy to try to reduce waste going to landfill [3]:
1 Reduce
2 Reuse
3 Recycling
4 Disposal
Waste incineration methods
This section describes how waste is used as fuel for energy generation.
Municipal solid waste incineration is preferable to land filling. Studies from DEFRA
show that EFW can be a preferable long term waste solution [4]. EFW still emits
carbon dioxide and is there for not a carbon neutral energy producer.
Moving grate incineration plants have as the name suggests a moving grate. The
waste is being moved through the combustion chamber on a grate. This is where the
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waste is being combusted/incinerated. The ash from the waste is removed to landfill.
[5]
The fluidised bed incineration plant is a technology that removes metal and heavy
particles before combustion. The fluidised bed is usually a hot sand bed being
fluidised by an air stream. The air stream is directed vertically to the bed. The
fluidised bed moves the waste into the furnace and is incinerated. [6]
Oscillating kiln incineration plants have the waste loaded onto a hopper which
regularly feeds waste to the kiln. Waste is delivered into the kiln and mixed with air to
get combusted. [7]
Other EFW methods
Mechanical Biological Treatment (MBT) with an anaerobic digestion to generate fuel
is one waste handling solution. MBT is a waste management process of several steps.
Sorting of waste is necessary to separate the biological waste. The biological waste is
then sent to Anaerobic Digestion (AD) which produces methane. It can then be used
as fuel for example in gas engines. The waste left is then re-sorted for metals and the
fraction of metals found is sent for recycling. This only leaves the RDF waste which
can be burnt in a small incineration plant on site. RDF is refused derived fuel. It is
waste such as paper, plastic, textiles and is considered to have a good combustion
quality [8].
Pyrolysis and Gasification processing can be used for handling waste. If the facility
were placed on site the waste would be heated under low oxygen (gasification) or no
oxygen (pyrolysis) presence. This creates a fuel that can be used in for example gas
turbine CHP plants. Cleaning of the gas is important before using it as fuel for energy
generation [9].
Energy From Waste Design
For MBT with AD processing involves pre sorting to separate the recycled objects.
The rest is then divided to AD and RDF. From AD the end products is mainly
methane which can be used for fuel. From the waste going into the MBT 20% is still
sent to landfill.
The energy output from the MBT plant with AD of 100000 tonne waste per year is
1.5MWel. This is created from the anaerobic digestion. The optimum size for an MBT
plant is 100000 tonne per year with the physical size approximated to 8 hectare to beeconomical viable. The technology is relatively unproven in the UK there is only one
full scale plant in Leicester city council.
For gasification and pyrolysis pre treatment and sorting of waste can be necessary.
The only proven plant in the UK is of clinical waste. Cleaning of the emission gases is
important. First it is held at 1250 °C for 2 second to destroy organic pollutants. The
gas then pass through a sodium bicarbonate filter to remove acidic residue. Before
being realised through a stack it passes a catalyser to remove nitrogen oxides.
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Gasification and pyrolysis is a clean process and is within the waste incineration
directive (WID) limit. It leaves between 10 to 15% bottom ash for non hazardous
landfill and approximately 5% fly ash. The fly ash is sent to a hazardous landfill.
The energy output from 30000 tonne wastes per year is 1.4MWel. The optimum size
for a plant is approximately less then 2 hectares for a 30000 tonne plant to beeconomical viable. The technology is a relatively unproven technology there is one
working gasification waste plant in the UK and it is dealing with hospital waste.
There is also one test plant for gasification municipal waste in Bristol.
Incineration by oscillating kiln, the waste can go untreated into the furnace. It reaches
temperatures of 1100 °C. Emissions for oscillating kilns are minimised by burning the
waste at a high temperature with the gas being cooled rapidly. Together with that the
emitted gas is filtered and chemical treated to remove particles and acidic residue. The
bottom ash created is 20 % of the waste input and is sent to a non hazardous landfill.
The fly ash created is 5 % of the waste input and it is sent to a hazardous landfill. This
means 25 % of the waste input to the oscillating kiln is sent to landfill. A 60000
tonnes plant per year would generate around 3MWel with a physical size of 1 hectare.Oscillating kiln incineration is a well proven technology in the UK [10].
Dioxins
Dioxins are persistent organic pollutants (POP). They are know to cause cancer in
humans and are carcinogenic. Dioxin levels in humans are mainly from the food
chain. They can also be absorbed from breathing from for example waste incineration
facilities emitting dioxins into the atmosphere.
To keep the dioxin levels low for waste incineration plants the temperatures whendioxins are created are avoided. Dioxins are formed when waste is being combusted
in temperature ranges of 250 to 400 °C. Dioxins are also formed in the cooling flues
in temperatures of 200 to 350 °C. It is created from unburnt carbon and metal
chlorides in the temperature ranges mentioned. Modern waste incineration plants are
within the WID limits allowed for dioxin.
According to a study (1996) on residents living near an incinerator plant in an urban
area in Italy it was found that there was a 6.7 fold increase in deaths from lung cancer
[11].
Advantages
• EFW can be used instead of landfill
Disadvantages
• EFW is not a renewable energy technology
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Energy from waste evaluation
The evaluation is assessed from the energy from waste section. There are three
different types of waste plants evaluated.
• MBT (Mechanical Biological treatment) with AD (Anaerobic digestion)
• Gasification and Pyrolysis
• Incineration (Oscillating kiln)
Evaluation of an MBT facility with an AD plant.
MBT with AD
Advantages
100000 tonne waste / year would generate1.5 MW energy
Well know technology in Europe
DisadvantagesLarge footprint 8 hectare when dealing with
100000 tonne waste/yr
The waste needs to be sorted
Emits carbon dioxideTable 12 shows key points for MBT with AD
The MBT waste needs space for sorting before processing and space is also needed
for the AD. The large space needed makes it a difficult process to have onsite in an
urban area. Together with that AD is odorous and the digestion process contains
bacteria’s which can be harmful for people. If the AD process is located away fromthe MBT site the transport between the two sites will increase the carbon dioxide
emissions.
Evaluation of a gasification and pyrolysis plant.
Gasification & Pyrolysis
Advantages
Relatively clean method to process waste
30000 tonne waste / year would generate1.4MW energy
DisadvantagesNew technology in the UK
The waste needs pre treating
2 hectare site for dealing with 30000tonne waste /yr
Emits carbon dioxideTable 13 shows key points for Gasification/Pyroysis
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The main advantages for gasification and pyrolysis are that it is seen as a clean
process and is promising for fuel generation.
Gasification and pyrolysis is a relatively new technology in the UK and
approximately 20% of the waste needs to be transported to landfill. There is one test
plant in Bristol with gasification of municipal waste. Hospital waste plant is the only
proven plant utilizing gasification in the UK
Evaluation of an oscillating kiln incineration.
Incineration Oscillating Kiln
Advantages60000 tonne / year would generate 3
MW energy
Technology well proven in the UK
Disadvantages60000 tonne waste/yr needed to be
economical viable25% of the waste residue is sent tolandfill
Emits carbon dioxideTable 14 shows key points for Oscillating kiln
It is a conventional incineration process and the waste plant can be designed to be
compact. It has higher emission values then gasification and pyrolysis 25% needs to
be sent for landfill.
EFW Selection
The selection is made from the energy from waste evaluation above and it is to not
have energy from waste systems on the Lots Road site.
The main reasons are:
• Energy from waste processes emits carbon dioxide and other pollutants
• The vast space required for a plant over ground in a dens urban area
• Transport of waste residues from an urban area to landfill increase emissions
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A2 Sustainable design systems
Sustainable design systems do not necessarily have to be energy generating systems in
the section below a few sustainable design systems are described.
A2.1 Green Roof
Green roof are sustainable design by planting vegetation on the roof. The main
purpose for green roof is as a passive solar design feature providing thermal barrier to
solar gains. It also decreases the fabric heat losses but this profit is secondary
compared to the main feature. Green roofs also reduce water run off from the building
and are visual attractive.
There are two types of green roofs intensive and extensive
Intensive green roofs:
Green roofs that require a lot of maintenance and artificial irrigation to stay functional
it can in addition to sustainable design also act as a roof garden and leisure space for
the residents.
Extensive green roofs:
Green roofs that requires low maintenance and no artificial irrigation it is design to be
a self sustaining plant community. Extensive green roofs are not used as a garden or
for leisure space. [1]
Technical description:
A green roof is constructed of several layers.
1 Vapour control
2 Insulation
3 Root resistant
4 Drainage and water protection
5 Filter fleece
6 Light weight substrate
7 Vegetation
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The vapour control is installed on the roof and then the other layers are stacked on top
from insulation to vegetation. [2]
Advantages
• Thermal barrier to solar gain• Reduces heat losses
• Visual attraction
• Reduce water runoff
• Insulation, reduce sound into the building
• CO2 reduction into the atmosphere, plants acquires an amount of CO2 for
photosynthesis.
Disadvantages
• Green roofs are not an energy generating system.
• A large load on the roof from planting a green roof requires a better (more
expensive) building structure.
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A2.2 Water Recovery
Rain Water Harvesting
The purpose is to get a sustainable water source by collecting rainwater and using it in
buildings. Rain water harvesting is mainly for toilet flushing if processed to potable
economical viability is difficult to achieve. It is usually more feasible to use rain
water harvesting for commercial and industry use than in domestic buildings.
Technical description:
1 Collection point on the roof
2 The water is lead through a filter to loose leaves and debris
3 The water is lead into the tank through the tank inlet
4 Water is pumped up through the suction filter at the tank outlet
5 The water passes through the filter up to pumps that distribute it to the toilets for
flushing
6 The system uses the main water supply as a back up system
7 In the tank there is an over flow trap in case of flooding
Figure 28 Simplified Harvesting system
It is always a question of health hazard to reuse water. Water is taken nearby the
water surface into the suction pumps. This is where the water is cleanest, heavy
particles and debris sink to the bottom of the tank. The tank water needs to be kept
aerobic to prevent malodour. There is minimal health risk to use rain water for toilet
flushing but some discoloration has to be accepted by the end user. [1] [2]
Collection point
Filter
Tank
Inlet
Suction filter
Pumps
WC WC WCOverflow trap
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Advantages
• Energy savings through water recovery
Disadvantages
• Low cost efficiency
• Requires high maintenance to ensure sufficient system operation
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Grey Water Recovery
The purpose is to save water by re-using water from the building (grey water). This is
for example shower water for toilet flushing.
Gray water needs to be disinfected and system controls have to be carried outregularly to ensure a sufficient operation. It can be used in residential buildings for
toilet flushing but economical feasibility is difficult to achieve. [3]
Advantages
• Energy savings through water recovery
Disadvantages
• Low cost efficiency
• Requires high maintenance to ensure sufficient system operation
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Appendix A List of Figures
Figure 1 Carbon dioxide cycle................................................................................................................ 93
Figure 3 Comparison between CHP and conventional network ........................................................... 101
Figure 4 Simplified explanation of gas turbine CHP ............ ............. ............ .............. ............. ............ 102
Figure 5 Simplified explanation of steam turbine CHP ........................................................................ 103 Figure 6 Simplified explanation of gas engine CHP ............................................................................ 105
Figure 7 Describing the Heat pump cycle ............................................................................................ 111
Figure 8 Vertical closed system............................................................................................................ 112
Figure 9 Horizontal pipe configurations [91] ....................................................................................... 113
Figure 10 Vertical pipe configurations [94] ......................................................................................... 114
Figure 11 Spiral coil design .................................................................................................................. 115
Figure 12 Energy pile configuration [97] ............................................................................................. 116
Figure 13 Energy slab configuration [98] ............................................................................................. 117
Figure 14 Open loop cooling system .................................................................................................... 117
Figure 15 Surface water cooling system .......... .............. ............. .............. ............ ............. .............. ..... 118
Figure 16 CoP changing with the condensation temperature. [104] ............. ............. .............. ............ . 121
Figure 17 showing a flat plate collector ............................................................................................... 123
Figure 18 Cross section tube……………………………………………………………………………………………………32
Figure 19ETC………………………………………………………………………………………….124
Figure 20 Showing a combi boiler [112(8)]. Note: SH stands for Space Heating ............. .............. ..... 126
Figure 21 PV panel configuration ........................................................................................................ 131
Figure 22 negative and positive semiconductor layers ......................................................................... 132
Figure 23 Simple schematic of PV [11]. .............................................................................................. 133
Figure 24 showing an aerofoil. ............................................................................................................. 137
Figure 25 showing a wind turbine [139, 4] ............ ............. ............ .............. ............. .............. ............ . 138
Figure 26 showing simplified drawings over the Nacelle .................................................................... 140
Figure 27 Annual mean wind speeds for the UK [152, 18] .................................................................. 143
Figure 28 Simplified Harvesting system .............................................................................................. 153
Appendix A List of Tables
Table 1 Showing calorific value of different fuels ................................................................................. 98
Table 2 Information from EPA Catalogue of CHP technologies 2002 [80 (13 ............. .............. ......... 106
Table 3 Showing CHP advantages and disadvantages ......................................................................... 109
Table 4 Showing average kWh/m2
and changes with tilt and direction ............................................... 127
Table 5 Showing the shadowing factor for SWH ................................................................................. 127
Table 6 Showing collector parameters ................................................................................................. 128
Table 7 Data of radiation for London [133, 18] ................................................................................... 134
Table 8 Semiconductor efficiencies...................................................................................................... 135
Table 9 Showing rotor diameters and energy output ............................................................................ 141
Table 10 Kinetic energy in the wind for average wind speeds ............................................................. 141 Table 11 Technical Data: Energy output for turbines at different wind speeds ............. .............. ......... 143
Table 12 shows key points for MBT with AD ..................................................................................... 149
Table 13 shows key points for Gasification/Pyroysis ........................................................................... 149
Table 14 shows key points for Oscillating kiln .................................................................................... 150
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Appendix A References
Biomass
[1] Royal Commission on environmental pollution, Biomass as a renewable energy source, UK, Royal
Commission on environmental pollution, 2004, p. 03
[2] ODPM, planning for renewable energy, A companion guide to PPS22, UK, OPDM, 2004, p.81-85
[3] Royal Commission on environmental pollution, Biomass as a renewable energy source, UK, Royal
Commission on environmental pollution, 2004, p. 09-29
[4] Royal Commission on environmental pollution, Biomass as a renewable energy source, UK, Royal
Commission on environmental pollution, 2004, p. 30
[5] Royal Commission on environmental pollution, Biomass as a renewable energy source, UK, Royal
Commission on environmental pollution, 2004, p. 03 figure 3-1
[6] U.S. Department of Energy [Home page on Internet] Energy Efficiency and Renewable Energy
[Cited 21-06-2007] Available from: http://www1.eere.energy.gov/biomass/pyrolysis.html#thermal
[7] U.S. Department of Energy [Home page on Internet] Energy Efficiency and Renewable Energy
[Cited 21-06-2007] Available from: http://www1.eere.energy.gov/biomass/gasification.html
[8] Petrov, Miroslav P, Biomass and Natural gas Hybrid combined cycles, M. Sc. Thesis report, Royalinstitute of technology, Stockholm Sweden, 2003
[9] Pettersson Mariane , Bakgrundsdokument for kriterieutveckling for pellets, for SIS miljomarkning
AB, SIS, Sweden, 2005
[10] The Engineering Toolbox [Home page on Internet] The Engineering Toolbox [Cited 10-04-2007]
Available from: http://www.engineeringtoolbox.com/fuels-higher-calorific-values-d_169.html
[11] Maunsell F, London Renewables Integrating renewable energy into new developments: Toolkit for
Planners, developers and consultants, London, Greater London Authority, 2004, p.62-63
ISBN:1852616601
[12] Royal Commission on environmental pollution, Biomass as a renewable energy source, UK,
Royal Commission on environmental pollution, 2004, p. 54
[13] ODPM, planning for renewable energy, A companion guide to PPS22, UK, OPDM, 2004, p.94-
113
[14] BIOS BIO ENERGY SYSTEMS Gmbh [Home page on Internet] BIOS [Cited 10-04-2007]
Available from: http://www.bios-bioenergy.at/en/electricity-from-biomass/biogas.html
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CHP
[1] Action energy, Good Practise Guide Combined heat and power in buildings, England, Carbon
Trust, 2004, p.30
[2] Town And Country Planning Association, Sustainable energy by design a TCPA `by design´ guide
for sustainable communities, London, TCPA, 2006, p. 37, ISBN:0902797395
[3] EPA U.S. Environmental and Protection Agency , Catalogue of CHP technologies, Technology
characterization: Gas turbines, U.S., EPA, 2002, p.06
[4] EPA U.S. Environmental and Protection Agency , Catalogue of CHP technologies, Technology
characterization: Gas turbines, U.S., EPA, 2002, p.04
[5] EPA U.S. Environmental and Protection Agency , Catalogue of CHP technologies, Technology
characterization: Steam turbines, U.S., EPA, 2002, p.04
[6] EPA U.S. Environmental and Protection Agency , Catalogue of CHP technologies, Technology
characterization: Steam turbines, U.S., EPA, 2002, p.09
[7] EPA U.S. Environmental and Protection Agency , Catalogue of CHP technologies, Technologycharacterization: Reciprocating engine, U.S., EPA, 2002, p.10
[8] EPA U.S. Environmental and Protection Agency , Catalogue of CHP technologies, Technology
characterization: Reciprocating engine, U.S., EPA, 2002, p.02
[9] EPA U.S. Environmental and Protection Agency , Catalogue of CHP technologies, performance
characteristics, U.S., EPA, 2002, p.07
[10] Royal Commission on environmental pollution, Biomass as a renewable energy source, UK,
Royal Commission on environmental pollution, 2004, p. 34
[11] Action energy, Good Practise Guide Combined heat and power in buildings, England, Carbon
Trust, 2004, p.04
[12] Maunsell F, London Renewables Integrating renewable energy into new developments: Toolkit for
Planners, developers and consultants, London, Greater London Authority, 2004, p.167
ISBN:1852616601
[13] Lowry Renaissance [Home page on Internet] Lowry Renaissance [Cited 05-06-2007] Available
from:
http://www.lowryhomes.com/titanicmill/sustainable_energy.asp?did=14&devPic1=titanic_logo.gif&de
vName=Titanic%20Mill
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GSHP
[1] IEA Heat ump Centre [Home page on Internet] IEA [Updated 14-05-2008, Cited 21-05-2007]
Available from: http://www.heatpumpcentre.org
[2] Rawlings Rosie, Ground source Heat Pumps a technology review, A BSRIA
Technical note, TN 18/1999, UK, 1999, executive summary section 2
[3] Maunsell F, London Renewables Integrating renewable energy into new developments: Toolkit for
Planners, developers and consultants, London, Greater London Authority, 2004, p.73,
ISBN:1852616601
[4] Rawlings Rosie, Ground source Heat Pumps a technology review, A BSRIA
Technical note, TN 18/1999, UK, 1999, p.07 figure 2.2
[5] Maunsell F, London Renewables Integrating renewable energy into new developments: Toolkit for
Planners, developers and consultants, London, Greater London Authority, 2004, p.72,
ISBN:1852616601
[6] Rawlings Rosie, Ground source Heat Pumps a technology review, A BSRIA
Technical note, TN 18/1999, UK, 1999, p.08 figure 2.3
[7] Rawlings Rosie, Ground source Heat Pumps a technology review, A BSRIA
Technical note, TN 18/1999, UK, 1999, p.08 section 2.3
[8] Enercret [Homepage on Internet] Enercret [Cited 18-07-2008] Available from:
http://www.enercret.com/page/english/enercret_system/how_it_works/how_it_works.html
[9] Cementation Foundations Skanska, [Homepage on Internet] Skanska [Cited 01-05-2008] Available
from: www.skanska.co.uk/files/graphics/CFS/Datasheets/Energy%20Piles.pdf
[9] Cementation Foundations Skanska, [Homepage on Internet] Skanska [Cited 01-05-2008] Available
from: www.skanska.co.uk/files/graphics/CFS/Datasheets/Energy%20Piles.pdf
[10] AGS The Association of Geotechnical and Geoenvironmental Specialists [Homepage on Internet]
AGS [Cited 10-05-2007] Available from:
www.ags.org.uk/aboutus/GeothermalEnergyandEnergyPiles.ppt
[11] Canada Renewable Energy Network Canren [Homepage on Internet] Canren [Cited: 05-04-2008]
Available from: www.canren.gc.ca/app/filerepository/B0126630E3FD4FFD91D2FC21C213724C.pdf
[12] Natural Resources Canada, Commercial Earth Energy Systems: A Buyers Guide, Canada, 2002
ISBN 0-662-32808-6
[13] Rawlings Rosie, Ground source Heat Pumps a technology review, A BSRIA
Technical note, TN 18/1999, UK, 1999, p.04
[14] Rawlings Rosie, Ground source Heat Pumps a technology review, A BSRIA
Technical note, TN 18/1999, UK, 1999, p.23
[15] IEA Heat ump Centre [Home page on Internet] IEA [Updated 14-05-2008, Cited 21-05-2007]
Available from: http://www.heatpumpcentre.org
[16] National Energy Foundation NEF [Homepage on Internet] NEF [Cited 21-04-2007] Available
from: www.nef.org.uk/gshp/documents/CE82-DomesticGroundSourceHeatPumps.pdf
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SWH
[1] Maunsell F, London Renewables Integrating renewable energy into new developments: Toolkit for
Planners, developers and consultants, London, Greater London Authority, 2004, p.50,
ISBN:1852616601
[2] U.S. Department of Energy EERE [Homepage on Internet] EERE [Cited: 18-07-2008] Available
from: http://www1.eere.energy.gov/solar/sh_basics_collectors.html#flatplate
[3]U.S. Department of Energy EERE [Homepage on Internet] EERE [Cited 18-07-2008] Available
from: http://www1.eere.energy.gov/solar/sh_basics_collectors.html#evacuatedtube
[4] Ashrae, HVAC application handbook, SI, Solar energy use, Ashrea, UK, 2003, p.33.7, figure 9
[5] Ashrae, HVAC application handbook, SI, Solar energy use, Ashrea, UK, 2003, p.33.8
[6] Ashrae, HVAC application handbook, SI, Solar energy use, Ashrea, UK, 2003, p.33.7
[7] Energy Savings Trust, Factsheet 3 Solar Water Heating, Energy Savings Trust, UK, 2005
[8] BRE, SAP 2005:The Government´s Standard Assessment Procedure for Energy Rating of Dwellings, Watford, DEFRA, 2005, p.29
[9] Ashrae, HVAC application handbook, SI, Solar energy use, Ashrea, UK, 2003, p.33.10
[10] Maunsell F, London Renewables Integrating renewable energy into new developments: Toolkit for
Planners, developers and consultants, London, Greater London Authority, 2004, p.51,
ISBN:1852616601
[11] Maunsell F, London Renewables Integrating renewable energy into new developments: Toolkit for
Planners, developers and consultants, London, Greater London Authority, 2004, p.52,
ISBN:1852616601
PV
[1] How Stuff Works [Homepage on Internet] How Stuff Works [Cited: 08-06-2008] Available from:
http://science.howstuffworks.com/solar-cell4.htm
[2] How Stuff Works [Homepage on Internet] How Stuff Works [Cited: 08-06-2008] Available from:
http://science.howstuffworks.com/solar-cell7.htm
[3] U.S. Department of Energy EERE [Homepage on Internet] EERE [Cited 18-07-2008] Available
from: http://www1.eere.energy.gov/solar/solar_cell_materials.html
[4] Maunsell F, London Renewables Integrating renewable energy into new developments: Toolkit for
Planners, developers and consultants, London, Greater London Authority, 2004, p.41,
ISBN:1852616601
[5] U.S. Department of Energy, DOE Solar Energy Technologies Program overviews and highlights,
U.S., 2006, p.07, DOE/GO-102006-2314
[6] Renewable Energy UK (REUK), [Homepage on Internet] REUK [Cited: 25-06-2007] Available
from: http://www.reuk.co.uk/40-Percent-Efficiency-PV-Solar-Panels.htm
[7] British Photovoltaic Association [Homepage on Internet] BPA [Cited: 20-04-2007] Available
from: http://www.greenenergy.org.uk/pvuk2/about/index.html
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[8] U.S. Department of Energy EERE [Homepage on Internet] EERE [Cited: 25-06-2008] Available
from: http://www1.eere.energy.gov/solar/solar_cell_materials.html
[9] How Stuff Works [Homepage on Internet] How Stuff Works [Cited: 10-05-2007] Available from:
http://science.howstuffworks.com/solar-cell3.htm
[10] U.S. Department of Energy EERE [Homepage on Internet] EERE [Cited: 23-06-2008] Availablefrom: http://www1.eere.energy.gov/solar/pv_basics.html
[11] How Stuff Works [Homepage on Internet] How Stuff Works [Cited: 13-05-2007] Available from:
http://science.howstuffworks.com/solar-cell6.htm
[12] DTI, Photovoltaic in Buildings, A design guide, UK, 1999, p.62
[13] U.S. Department of Energy EERE [Homepage on Internet] EERE [Cited: 23-06-2008] Available
from: http://www1.eere.energy.gov/solar/bos.html
[14] DTI, Photovoltaic in Buildings, A design guide, UK, 1999, p.12
[15] DTI, Photovoltaic in Buildings, A design guide, UK, 1999, p.9-12
[16] Maunsell F, London Renewables Integrating renewable energy into new developments: Toolkit for
Planners, developers and consultants, London, Greater London Authority, 2004, p.41-42,
ISBN:1852616601
[17] DTI, Photovoltaic in Buildings, A design guide, UK, 1999, p.9 figure 2.13
[18] DTI, Photovoltaic in Buildings, A design guide, UK, 1999, p.10 figure 2.14
[19] Maunsell F, London Renewables Integrating renewable energy into new developments: Toolkit for
Planners, developers and consultants, London, Greater London Authority, 2004, p.42,
ISBN:1852616601
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Wind Power
[1] Princeton [Homepage on Internet] Princeton [Cited: 11-06-2008] Available from:
http://www.princeton.edu/~asmits/Bicycle_web/Bernoulli.html
[2] Danish Wind Industry Association [Homepage on Internet] Danish Wind Industry Association
[Cited: 11-06-2008] Available from: http://www.windpower.org/en/tour/wtrb/lift.htm
[3] Danish Wind Industry Association [Homepage on Internet] Danish Wind Industry Association
[Cited: 11-06-2008] Available from: http://www.windpower.org/en/tour/wtrb/comp/index.htm
[4] [Homepage on Internet] Princeton [Cited: 11-04-2007] Available from: http://www.renewables-
made-in-germany.com/fileadmin/user_upload/product/51/51_subimg1_web_web.jpg
[5] How Stuff Works [Homepage on Internet] How Stuff Works [Cited: 08-05-2007] Available from:
http://science.howstuffworks.com/wind-power1.htm
[6] Hoare Lea Consulting [Internal Report], Wind turbine installation preliminary feasibility study for
National marine aquarium, Bristol, Hoare Lea Consulting, 2005
[7] Danish Wind Industry Association [Homepage on Internet] Danish Wind Industry Association[Cited: 11-06-2008] Available from: http://www.windpower.org/en/tour/wtrb/electric.htm
[8] Danish Wind Industry Association [Homepage on Internet] Danish Wind Industry Association
[Cited: 11-06-2008] Available from: http://www.windpower.org/en/stat/betzpro.htm
[9] Danish Wind Industry Association [Homepage on Internet] Danish Wind Industry Association
[Cited: 11-06-2008] Available from: http://www.windpower.org/en/tour/wtrb/size.htm
[10] Energy Savings Trust, Factsheet 6 Small Scale Wind Energy, Energy Savings Trust, UK, 2005
[11] Danish Wind Industry Association [Homepage on Internet] Danish Wind Industry Association
[Cited: 11-06-2008] Available from: http://www.windpower.org/en/stat/unitsw.htm#anchor1345942
[12] Danish Wind Industry Association [Homepage on Internet] Danish Wind Industry Association
[Cited: 11-06-2008] Available from: http://www.windpower.org/en/tour/wres/weibull.htm
[13] Energy Savings Trust, Factsheet 6 Small Scale Wind Energy, Energy Savings Trust, UK, 2005
[14] Building service journal, wind and the global warming imperative, BSJ, UK, 2006
[15] Hoare Lea Consulting [Internal Report], Wind turbine installation preliminary feasibility study for
National marine aquarium, Bristol, 2005
[16] CIBSE, Guide A: Environmental Design, CIBSE, UK, p.28
[17] Maunsell F, London Renewables Integrating renewable energy into new developments: Toolkit for
Planners, developers and consultants, London, Greater London Authority, 2004, p.92-93,ISBN:1852616601
[18] DTI [Homepage on Internet] DTI [Cited: 11-06-2008] Available from:
http://www.mike.munro.cwc.net/alt_e/windpow/windmon/nobl_c.gifa
[19] Hoare Lea Consulting [Internal Report], Wind turbine installation preliminary feasibility study for
National marine aquarium, Bristol, 2005
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[20] Maunsell F, London Renewables Integrating renewable energy into new developments: Toolkit for
Planners, developers and consultants, London, Greater London Authority, 2004, p.43,
ISBN:1852616601
[21] Danish Wind Industry Association [Homepage on Internet] Danish Wind Industry Association
[Cited: 11-06-2008] Available from: http://www.windpower.org/en/tour/econ/index.htm
[22] Hoare Lea Consulting [Internal Report], Wind turbine installation preliminary feasibility study for National marine aquarium, Bristol, 2005
EFW
[1] DEFRA, Waste implementation programme version 2, 2005 July, UK, DEFRA, p.02,
[2] ODPM, planning for renewable energy, A companion guide to PPS22, UK, OPDM, 2004, p.94
[3] DEFRA, Waste implementation programme version 2, 2005 July, UK, DEFRA, p.03
[4] DEFRA , Impact of energy from waste and recycling policy on UK Greenhouse gas emissions,
2006, UK, DEFRA
[5] DEFRA, Waste implementation programme version 2, 2005 July, UK, DEFRA, p.15
[6] DEFRA, Waste implementation programme version 2, 2005 July, UK, DEFRA, p.15 [7] Viridor, The Exeter Area Energy for Waste Initiative, Don’t let Devon go to waste, 2006, UK,
Viridor p.06
[8] Viridor, The Exeter Area Energy for Waste Initiative, Don’t let Devon go to waste, 2006, UK,
Viridor p.05
[9] DEFRA, Waste implementation programme version 2, 2005 July, UK, DEFRA, p.16
[10] Viridor, The Exeter Area Energy for Waste Initiative, Don’t let Devon go to waste, 2006, UK,
Viridor p.05-07
[11] Greenpeace [Homepage on Internet] Greenpeace [Cited: 20-04-2007] Available from:
www.greenpeace.org.uk/MultimediaFiles/Live/FullReport/3809.PDF
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Green Roof
[1] Hoare Lea Consulting,[Internal Report] Hoare Lea sustainable report: Adnams Distribution Centre
– Reydon, Bristol, Hoare Lea Consulting,
[2] Blackdown Horticultural Consultants Limited [Homepage on Internet] Blackdown HorticulturalConsultants Limited [Cited: 22-06-2007] Available from:
http://domain879190.sites.fasthosts.com/greenroofs.htm#construction
Water Recovery
[1] Hoare Lea Consulting,[Internal Report] Hoare Lea sustainable report: Adnams Distribution Centre
– Reydon, Bristol, Hoare Lea Consulting,
[2] BSRIA, Rainwater and Greywater in buildings Project report and case studies, Section Rainwater,
UK, BISRA
[3] BSRIA, Rainwater and Greywater in buildings Project report and case studies, Section Rainwater,
UK, BISRA
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Appendix B Calculations & Technical Data
B1 Peak Loads, Diversity and Thermal Base load
The thermal peak load for a flat estimated below is small because of the diversity
around the site. This is the probability of thermal energy usage, e.g. the probability of
every one using showers and space heating at the same time is very low.
The electrical peak load for one flat is also small because of the diversity around the
site. This is the probability of electrical energy usage e.g. the probability of every one
using there electrical appliances at the same time is very low.
B1.1 Peak Load Calculations
North side
The north side thermal demand is 5900 MWh/year
The thermal peak load is the instant thermal load.
Hoare Lea consulting uses a rule of thumb of 5 kW for a regular flat to get the total
thermal peak load. [1]
There are 448 flats and the instant thermal load per flat is 5 kW
This equals a Thermal Peak load of 5 x 448= 2240 kW Equation (1a)
The biomass boilers are sized for the thermal peak load since the solar water heating
performance is unreliable.
The peak thermal load of the north side is achieved by two 1200 kW boilers.
The electrical peak load is the instant electrical load
For the electrical peak load Hoare Lea consulting uses a rule of thumb of 2 kW for a
regular flat. [2]
There are 448 flats and the instant electrical load per flat is 2 kW
This equals an Electrical Peak load of
2 x 448= 896 kW Equation (1b)
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South side
The south side thermal demand is
8500 – 5900 = 2600 MWh/year Equation (3)
There are 255 flats and the instant thermal load per flat is 5 kW
This equals a Thermal Peak load of 5 x 255= 1275 kW Equation (2a)
There are 255 flats and the instant electrical load per flat is 2 kW
This equals an Electrical Peak load of 2 x 255= 510 kW Equation (2b)
B1.2 Thermal base Load
The thermal base load is the minimum thermal demand for the Lots Road site.
From discussions with Hoare Lea consulting the thermal base load were selected to
2000 watts per flat. [3] The Lots Road site has approximately 700 flats so the sites
base load is set to 1400kW.
2 x 700 = 1400 kW Equation (4)
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B2 Roof Space for the Final Recommendation
The roof space on the Lots Road site blocks are checked from the architectural
drawings [13]. Solar water heating panels are placed on available roof space where
they are efficient e.g. facing in a southerly direction and not being shaded at any
point. They are not placed on Block GG, Block FF and Block HH.
Available roof space (m2) from the architectural drawings:
Block AA: 20 x 10
Block BB: 40 x 10
Block CC: 20 x 10
Block DD: 40 x 10
Block EE: 20 x 10
Block JJ: 135 x 20
= 4100 m2
The energy output available from one square meter of SWH panel per year is
454 kWh. 454 kWh/(year*m2) is a rule of thumb from the (London toolkit 2004) [4].
Available roof space multiplied with the SWH panel rule of thumb equals
454 x 4100 = 1861 MWh/year Equation (5)
Equation (5) shows that SWH can provide approximatley1800 MWh/year. For the
final recommendation 1700 MWh/year are assumed to be provided from SWH
panels.
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B3 Photovoltaic for the Final Recommendation
Photovoltaic is placed on the north tower (Block GG) Estimated roof space on the
tower is 50m2
x 25m2
= 1250m2
1 kW peak (kWp) delivers approximately 750 (kWh/year) from a photovoltaic panelwith 15 % efficiency. The roof space needed to deliver 1 kWp is 8 m
2of panel from
the London toolkit 2004 [5].
In order to get the photovoltaic energy output, the total roof area is divided with 8 m2
to get the total kWp available. The kWp is then multiplied with 750 (kWh/year) to get
the energy output.
1250/8=156.25 kWp Equation (6)
156.25 x 750 = 117.2 MWh/year Equation (7)
117.2 (MWh/year) are approximately 2.6 % of the electrical demand for the Lots
Road site.
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B4 Carbon dioxide efficiency
The carbon dioxide efficiency for the different energy systems are evaluated from
delivering 20 % of the yearly energy demand. Total energy demand for the Lots Road
site is 13000 (MWh/year)
20% of the Lots Road site energy demand is then 2600 MWh/year
13000 x 0.20 = 2600 MWh/year Equation (8)
The carbon dioxide reductions for the Lots Road site are compared to conventional
heating from a gas boiler and electricity delivered from the grid.
The total Lots Road site carbon dioxide emissions are approximately
4000000 CO2 kg/year.
This is from the equation:
(8500000 / 0.78) x 0.194 + 4500000 x 0.4222 = 4013.103 CO2 ton/year Equation (9)
8500000 (kWh/year) is the thermal demand for the Lots Road site
4500000 (kWh/year) is the total electrical demand for the Lots Road site
0.194 (CO2 kg/kWh) is the conversion factor for natural gas [6]
0.4222 (CO2 kg/kWh) is the conversion factor for electricity from the grid [6
0.78 is the estimated boiler efficiency from appendix R, notional building, in SAP
2005 [7].
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B4.1 Biomass
The biomass boilers provide thermal energy and when delivering 20% of the yearly
energy demand (2600 (MWh/year)).
The savings will be:
2600000 / (0.78) x 0.194 = 646666.7 kgCO2 /year Equation (10)
The percentage carbon dioxide emissions saved are then:
(646666.7/4000000) x 100 = 16.16 % Equation(11)
B4.2 Biomass CHP
Biomass CHP with an efficiency of 80% and a power to heat ratio of 1:1.286, from
the carbon trust [8]
When producing 1137358 (kWh/year) electricity and 1462642 (kWh/year) of heat the
CHP system produces approximately 20% of the yearly energy demand.
The savings will be:
(1462642/0.78) x 0.194 + 1137358 x 0.4222= 843750.4 kgCO2 /year Equation(12)
The percentage carbon dioxide emissions saved are then:
(843750.4 /4000000) x 100 = 21.09 % Equation (13)
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B4.3 CHP
Gas engine CHP with an efficiency of 80% and a power to heat ratio of 1:1.286 from
the carbon trust [8]
When producing 1150000 (kWh/year) electricity and 1477750 (kWh/year) of heat theCHP system produces roughly 20% of the yearly energy demand.
The savings will be:
((1462642/0.78) x 0.194 + 1137358 x 0.422) – (2600000/0.80 x 0.194) =
213250 kgCO2 /year Equation (14)
This is the emissions saved from conventional energy generation subtracting the
emissions for the natural gas used in the CHP engine.
The percentage carbon dioxide emissions saved are then:
(213250/4000000) x 100 = 5.33 % Equation (15)
B4.4 GSH
The ground source heating system will deliver thermal energy and when delivering
20% of the yearly energy demand (2600 (MWh/year))
It is calculated assuming that the heat pump has a CoP of 4 i.e. electricity to thermalratio 1:4.
The savings will be:
(2600000/0.78 x 0.194) – ((1/4) x (2600000 x 0.4222)) =
372366.7 kgCO2 /year Equation (16)
The savings are the thermal energy (gas boiler) emissions subtracting the emissions
from the electrical pump in the GSH system.
The percentage carbon dioxide emissions saved are then:
(372366.7/4000000) x 100 = 9.31 % Equation (17)
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B4.5 Photovoltaic
The photovoltaic system will deliver electricity and when delivering 20 % of the
yearly energy demand (2600 (MWh/year)).
The savings will be:
2600000x 0.422= 1097200 kgCO2 /year Equation (18)
The percentage carbon dioxide emissions saved are then:
(1097200/4000000) x 100 = 27.43 % Equation (19)
B4.6 Solar Water Heating
The solar water heating system will deliver thermal energy and when delivering 20%
of the yearly energy demand (2600 (MWh/year)).
2600000/(0.78) x 0.194 = 646666.7 kgCO2 /year Equation(20)
The percentage carbon dioxide emissions saved are then:
(646666.7/4000000) x 100 = 16.16 % Equation(21)
B4.7 Wind power
The wind power system will deliver electricity and when delivering 20 % of the
yearly energy demand (2600 (MWh/year)).
The savings will be:
2600000x 0.422 = 1097200 kgCO2 /year Equation (22)
The percentage carbon dioxide emissions saved are then:
(1097200/4000000) x 100 = 27.43 % Equation (23)
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B5 Cost
The cost estimation for the systems below is from information found in the London
toolkit [9] and from the Hoare Lea Consulting internal report (The Holland street
buildings Energy Review) [10].
No considerations have been made to site limitations of for example if it is physical
possible to have solar water heating panels all over the site.
The cost for an energy system differs depending on source. Here the lowest
reasonable cost for an energy system is selected. This is seemed reasonable since
renewable energy and CHP is becoming more and more available.
The cost below is in pounds per kilowatt (£/kW) or pounds per square meter (£/m2)
Energy Cost Unit
SWH 1460
400
£/kW
£/m2
GSH 800 £/kW
Biomass 200 £/kW
Wind Power 2000 £/kW
PV 2482
850
£/kW
£/m2
Biomass CHP 2720 £/kWe
CHP 1000 £/kWthTable 1 Ccost per kilowatt or square meter of the energy technologies
kWe is when the output is in electricity and kWth is when the output is in thermal energy.
The estimated capital cost of the energy systems is calculated for 1500 (MWh/year)
by multiplying the system size kW with the cost (£/kW). The cost it is shown below
in Table 2.
Energy & System size Cost (£)
SHW 822 (kW) 1,200,000
GSH 1125 (kW) 900,000
Biomass 700 (kW) 140,000
Wind Power 570 (kW) 1,140,000
PV 5480 (kW)
13,601,360
Biomass CHP 140 (kWe) 380,800
CHP 180 (kWth) 180,000
Table 2 Showing cost for energy systems.
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B6 System sizing
The system sizing uses rule of thumbs and Hoare Lea Consulting guidelines to
achieve a reasonable system size for delivering 1500 MWh/year. Below are
explanations to the system sizing in table 2 in appendix B5 on page 173.
B6.1Solar water heating
The required roof area to provide the 1500 (MWh/year would be
approximately 3000 m2
the system size for SWH is then 822 kW.
This report has made an approximation to 5 working hours per day with 100%
efficiency for the SWH panel.
The solar water heating system approximately delivers 500 (kWh / (m2xyear))
[10].
Below is a calculation to show that it meets the 1500 (MWh/year) energy
demand.
822 x 5 x 365 = 1500150 (kWh / year) Equation (24)
B6.2 Ground source heating
The heat pump is estimated to have a coefficient of performance (CoP) of 4.It
means that for 4 units of thermal energy 1 unit electricity is used.
The working hours for the heat pump are set to 1,500 hours per year which is
chosen from the Hoare Lea Consulting internal report [10].
The system size is then 1125 kW.
Below is a calculation to show that it meets the 1500 (MWh/year) energy
demand.
1125 x 1500 = 1687500 (kWh / year) Equation (25)
B6.3 Wind power
The wind turbine efficiency is estimated to 30% of the turbine rating. This is a
rule of thumb from the energy savings trust [11].
The estimated turbine size is set to 570 kW.
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Below is a calculation to show that it meets the 1500 (MWh/year) energy
demand.
570 x 0.3 x 365 x 24 = 1497960 (kWh / year) Equation (26)
0.3 is the 30 %570 is the turbine output.
365 x 24 is the amount of hours in a year.
B6.4 Photovoltaic
The PV panel is estimated to 750 (kWh/per kWp) with a 15% efficiency it
then needs 8 m2
panel per kWp [4].
This report has made an approximation to 5 working hours per day for the PV
panel.
The cost from the London toolkit is 850 £/m2
[9].
The system size is then 5480 kW. This would require a panel physical size of
approximately 16002 m2. There is therefore not enough roof space available at
the Lots Road site to deliver 1500 MWh/year.
Below is a calculation to show that it if space were available it would have
meet the 1500 (MWh/year) energy demand.
5 x 365 5480 x 0.15 = 1500150 (kWh / year) Equation (27)
B6.5 Biomass
The system size for biomass is estimated to 700 kW working 2200 hr/year.
The working hours for biomass are set to 2,200 hours per year which is chosen
from the Hoare Lea Consulting internal report [25].
Below is a calculation to show that it meets the 1500 (MWh/year) energy
demand.
700 x 2200 = 1540000(kWh / year) Equation (28)
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B6.6 Combined heat and power
The working hour for the CHP is from a Hoare Lea Consulting internal report
[25It is estimated to 5000 hours per year. The system size for the CHP engine
is 180 kW (thermal energy) with a power to heat ratio of 1:1.286. The power
to heat ratio is from the carbon trust [8].
Below is a calculation to show that CHP meets the 1500 (MWh/year) energy
demand.
180 x 5000 x 0.777 + 180 x 5000 = 1600000 (kWh /year) Equation(29)
B6.7 Biomass CHP
The 1500 (MWh/year) is achieved when working 5000 hours per year. The
system size is estimated to 140 kWe with a power to heat ratio of 1:1.286. Thepower to heat ratio is from the carbon trust [8].
Below is a calculation to show that it meets the 1500 (MWh/year) energy
demand.
140 x 5000 + 140 x 5000 x 1.286 = 1600000 (kWh / year Equation(30)
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B7 Payback time
The payback time for the different renewable energies are not shown in the report it is
only calculated here in appendix B7. The capital cost is divided with the savings for
one year. For example the wind power savings are 106800 pounds per year and the
capital cost from table 5 in appendix B5 on page 173 is 1,140,000 £.
The payback time for wind power is then:
1140000 / 106800 = 11.3 years Equation (31)
The payback times investigated are for the system output of 1500 (MWh/year). The
capital cost can be seen in table 5
The prices used are from SAP 2005 [12]
Main gas: 1.63 p/kWh
The price for electricity the standard tariff is 7.12 p/kWh.
The price for natural gas is 1.39 p/kWh.
The price for biomass fuel (wood chips) is 1.60 p/kWh.
B7.1 Wind power
1500000 kWh x 7.12 p/kWh)= 10680000 pence = 106800 pounds (£) Equation(32)
The savings for one year of wind power is 106800 £. Wind power then have a
payback time of 11.3 years.
B7.2 Biomass
Savings in one year
(1500000 kWh x 1.63 p/kWh) x 10-2
= 24450 £ Equation(33)
Subtracting the cost of the biomass fuel
24450 – (1500000 x 1.60) x10-2
= 450 £ Equation(34)
The savings for biomass for one year is 450 £. Biomass then has a payback time of
over 100 years.
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B7.3 Photovoltaic
1500000 kWh x 7.12 p/kWh)= 10,680,000 pence = 106,800 pounds (£) Equation(35)
The savings for photovoltaic for one year is 106,800 £. Photovoltaic then have apayback time of over 100 years.
B7.4 Ground source heating
GSH using a CoP of 4
Savings in one year
(1500000 kWh x 1.63 p/kWh) x 10
-2
= 24450 £ Equation(36)
Subtracting the electricity bought from the grid
(1500000 kWh x ¼ x 7.12 p/kWh) x 10-2
= 26,700 Equation(37)
24450 - 26700 = - 2250 £ Equation(38)
2250 £ per year and that is more expensive then to generate 1500 MWh energy with
conventional energy.
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B7.5 CHP
CHP with the ratio 1:1.286
Savings in one year
(656167.97 kWh x 1.63 (p/kWh)) + (843832 kWh x 7.12 p/kWh)
= 7077637 Pence Equation(39)
This equals 70776.37pounds (£)
Subtracting the cost of natural gas used in the gas engine CHP
(1,500,000 x 1.39 (p/kWh)) x 10-2
= 20850 pounds (£) Equation(40)
70776.37 – 20850 = 49926.37 £ Equation(41)
The savings for CHP for one year is roughly 50000 £. CHP then have a payback time
of 4 years.
B7.6 Biomass CHP
Savings in one year
(656167.97 kWh x 1.63 (p/kWh)) + (843832 kWh x 7.12 p/kWh)
= 7077637 Pence Equation(42)
This equals 70776.37 pounds (£)
Subtracting the cost of biomass fuel
1,500,000 x 1.60(p/kWh) = 24000 £ Equation(43)
70776.37 – 24000 = 46776.37£ Equation(44)
The savings for biomass CHP for one year is 46776.37 £. Biomass CHP then has a
payback time of approximately 8 years
B7.7 Solar water heating
Savings in one year
(1500000 kWh x 1.63 p/kWh) = 24450 £ Equation(45)
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The savings for SWH for one year is 24450 £. SWH then have a payback time of 50
years.
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B8 Guidelines and Regulations
This section shows some of the national targets the UK has set out to reduce its
carbon dioxide footprint.
Parts of the Mayors energy strategy and supplementary planning guidance are statedto show London’s attempt to be more energy efficiency and to emit less carbon
dioxide. The supplementary planning guidance also states that 10% carbon emission
reduction should be made from onsite renewable energies. The planning guidance
promotes sustainable design for building developments and states that the Mayors
preferred standard is to have zero carbon emission developments (ZED).
Excerpts of Part L1A are included because Part L1A is the building regulations
section on conservation of fuel and power for new dwelling developments. In Part
L1A is the regulations on emission reductions for new dwelling developments.
The last part of this section is on the government’s standard assessment procedure
SAP. This is the government’s method to assess dwelling developments energy
performance.
The Lots Road site is in this report assumed to be a new dwelling development.
In 2006 the new development standard changed to 20% carbon dioxide reduction
from the current building standard [14].
B8.1 National targets from the government
The Government has set out targets to reduce UK carbon dioxide emissions.
Excerpt of Government targets, form The Mayors Energy strategy 2004 [15]
• Reduce UK greenhouse gas emissions to 12.5 % below 1990 levels by 2008-
2012 (legally binding obligation of the Kyoto Protocol)
• Reduce UK carbon dioxide (CO2) emissions to 20% below 1990 levels by2020. Aiming for CO2 emissions equivalent to 22-29 % below 2000 levels by
2020.
• A goal of putting the UK on a path to achieving a 60% reduction in CO2
emissions, relative to 2000, by 2050
• To meet 10% of UK electricity demand from renewable energy
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B8.2 The Mayors energy strategy
The Mayor of London, Ken Livingstone, has published the Mayor’s energy strategy
this is to decrease the carbon dioxide emissions in London. The Mayor wants to make
it easier for Londoners that want to install renewable energy sources. The Mayor also
wants all boroughs within London to have at least one Zero Carbon emissionDevelopment (ZED) by 2010 [16].
Below are excerpts from The Mayors energy strategy
Figure 1 Excerpts from the Mayors energy strategy
The Mayor’s Energy Hierarchy
Figure 2 The Mayors energy hierarchy
The Mayor of London will use his powers to achieve targets for London. They are
aimed at 665 GWh and 280 GWh generated from renewable energies by 2010. This
will generate electricity for 100000 homes and heat for 10000 homes.
This will be achieved by the targets below [17]:
-7000 domestic photovoltaic systems
-250 public and commercial photovoltaic systems
-Reducing London’s contribution to climate change by minimizing
emissions of carbon dioxide from all sectors (commercial, domestic, industrial
and transport.
-Helping to eradicate fuel poverty by giving Londoners, particularly the
most vulnerable groups, access to affordable warmth.
-Contributing to London’s economy by increasing job opportunities
and innovation in delivering sustainable energy, and improving London’s
housing and other building stock.
1 Use less energy (Be Lean) - To minimize demand for energy
2 Use renewable energy (Be Green) -As much energy as possible should comefrom zero-carbon sources, so climate change impact is reduced, and natural
resources conserved
3 Supply energy efficiently (Be Clean) - Where it is not practical to use renewable
energy, the energy should be supplied as efficiently as possible - for example from
combined heat and power, so that the fossil fuel is minimized, further reducing
overall carbon dioxide emissions.
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B8.4 Part L compliance
The regulations for conservation of fuel and power that new developments have to
comply with are confined in the Part L document. It is part of the British
government’s building regulations. Part L1A a section of part L is the part for newdwelling developments for conservation of fuel and power.
Below is an excerpt from Part L1A [20]
Figure 4 Excerpt from Part L1A
Part L Conservation of fuel and power
L1. Reasonable provision shall be made for the conservation of fuel and
power in buildings by:
A, limiting heat gains and losses
i, through thermal elements and other parts of the building fabricii, from pipes ducts and vessels used for space heating space cooling and hot
water services
B, providing and commissioning energy efficient fixed building services with
effective controls
C, providing to the owner sufficient information about the building ,the fixed
building services and their maintenance requirements so that the building
can be operated in such manner as to use no more fuel and power than is
reasonable in the circumstances
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Criterions are shown below from Part L1A [21]
Figure 5 Excerpt from Part L
Explanation of Part L1A criterions:
Criterion1: To make sure the buildings do not have to high CO2 emissions. This
means the DER emissions shall be lower then the TER emissions. TER is a 20%reduction in emissions compared to a notional building. A notional building is
explained in the SAP section.
Criterion2: Limit flexibility in design so tradeoffs are discouraged. This means that
because renewable energies are implemented the building can not have poor design,
for example high heat gain and poor insulation and pass the energy efficient
requirements.
Criterion3: Elimination of AC, if possible, to save energy by countering internal heat
gains.
Criterion4: To achieve specified air permeability rate to limit excessive energy losses.
Criterion5: Awareness amongst residents as a part of sustainable design, for example
using low energy light bulbs.
Criterion 1: the prediction rate of CO2 from dwelling (the dwelling
emission rate DER) is not greater then Target emission rate (TER).
Criterion2:Building fabrics and building service performance arewithin limits.
Criterion3: limit the effect of solar gain in the summer.
Criterion 4: Air tightness is checked with pressure tests (NDT) and
commissioning.
Criterion 5: Awareness to residents to achieve energy efficiency in use
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B8.5Standard Assessment Procedure (SAP)
The government’s method of assessing dwellings energy and environmental (CO2)
performance are with SAP. The important performance in order to get planning
permission is the CO2 emission rate. The dwelling carbon dioxide emission rate is
assessed by using a notional building as a reference frame with the same dimensionsas the dwelling development. Then the dwelling development is calculated and
compared to the notional building regarding to the CO2 emission rate. The dwelling
development should perform better, lower emission rate, then the notional building.
According to the new building standards the target is a carbon dioxide emission rate
reduction of 20%. [22]
The total carbon dioxide emissions are calculated in CO2 kg/year for the development.
It is then divided with the area (m2) of the dwelling to get the dwelling CO2 emission
rate (CO2 kg/m2 /year). If renewable technologies are used the CO2 emissions saved by
the renewable technologies are subtracted from the total CO2 emissions to get a lower
dwelling carbon dioxide emission rate.
The energy performance is assessed through how large the energy demand is for a
dwelling (kWh/year) multiplied with the cost/kWh to get the total energy cost. The
total energy cost is then multiplied with a cost deflator, the value of the deflator is
found in the SAP documents. The SAP guide tables then provide the SAP rating
number.
The rating for the energy performance is between 1 to100 (high score equals good
performance e.g. low energy cost per year).
SAP work as a general assessment tool for CO2 emissions this means that it is
independent of the resident’s energy use or usage of the floor area. It only depends on
general factors of energy performance such as building ventilation and energy sources
used.
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B9 Block Technical Data
Below are the net areas and the energy demands for the nine blocks at the Lots Road
site, information from Hoare Lea Consulting.[23]
B9.1 Technical Data for Block JJ
Block JJ Net area 40446 m2
Residential
Residential area of Block JJ: 85% oftotal
Units with Comfort cooling: 237
Affordable units:0
Electricity use 50/kWh/m2 /year
Gas use 80/kWh/m
2
/yearEnergy demand for the residential area: 4469283kWh/year
Office
Office area of Block JJ: 10% of total
Electricity use 128/kWh/m2 /year [
Gas use 97/kWh/m2 /year
Energy demand for the office area: 910485kWh/year
Retail
Retail area of Block JJ: 5% of total
Electricity use 234/kWh/m2 /year
Gas use 65/kWh/m2 /year
Energy demand for the retail area: 604667.7kWh/year
Total energy demand for Block JJ: 5984435 kWh/yearTable 3 showing technical data for block JJ
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B9.2 Technical Data for Block HH
Block HH Net area 9263m^2
Residential
Residential area of Block HH: 88% of
total
Units with Comfort cooling: 0
Affordable units:136
Electricity use 40/kWh/m2 /year
Gas use 80/kWh/m2 /year
Energy demand for the residential area: 978172kWh/year
Retail
Retail area of Block HH: 12% of total
Electricity use 234/kWh/m2 /year
Gas use 65/kWh/m
2
/yearEnergy demand for the retail area: 332356.44kWh/year
Total energy demand for Block HH 1310528.44 kWh/yearTable 4 showing technical data for block HH
B9.3 Technical Data for Block GG
Block GG Net area 12931m^2
Residential
Residential area of Block GG: 95 % oftotal
Units with Comfort cooling: 75
Affordable units:0
Electricity use 50/kWh/m2 /year
Gas use 80/kWh/m2 /year
Energy demand for the residential area: 1596978.5kWh/yearRetail
Retail area of Block GG: 5% of total
Electricity use 234/kWh/m2 /year
Gas use 65/kWh/m2 /year
Energy demand for the retail area: 193318.45kWh/year
Total energy demand for Block GG 1790296.95 kWh/yearTable 5 showing technical data for block GG
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B9.4 Technical Data for Block FF
Block FF Net area 6997 m^2
Residential
Residential area of Block FF: 95 % of
total
Units with Comfort cooling 51
Affordable units:0
Electricity use 50/kWh/m2 /year
Gas use 80/kWh/m2 /year
Energy demand for the residential area: 864129.5 kWh/yearRetail
Retail area of Block FF: 5% of total
Electricity use 234/kWh/m2 /year
Gas use 65/kWh/m2 /year
Energy demand for the retail area: 104605.15kWh/year
Total energy demand for Block FF 968734.65 kWh/yearTable 6 showing technical data for block FF
B9.5 Technical Data for Block EE
Block EE Net area 4465 m^2
Residential
Residential area of Block EE: 100 % oftotal
Units with Comfort cooling 36
Affordable units:0
Electricity use 50/kWh/m2 /year
Gas use 80/kWh/m2 /year
Energy demand for the residential area: 580450 kWh/year
Total energy demand for Block EE 580450 kWh/yearTable 7 showing technical data for block EE
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B9.6 Technical Data for Block DD
Block DD Net area 4856 m^2
Residential
Residential area of Block DD: 100 % of
total
Units with Comfort cooling 36
Affordable units:0
Electricity use 50/kWh/m2 /year
Gas use 80/kWh/m2 /year
Energy demand for the residential area: 631280 kWh/year
Total energy demand for Block DD 631280 kWh/yearTable 8 showing technical data for block DD
B9.7 Technical Data for Block CC
Block CC Net area 2706
Residential
Residential area of Block CC: 100 % oftotal
Units with Comfort cooling 18
Affordable units:0
Electricity use 50/kWh/m2 /year
Gas use 80/kWh/m2 /year
Energy demand for the residential area: 351780 kWh/year
Total energy demand for Block CC 351780 kWh/yearTable 9 showing technical data for block CC
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B9.8 Technical Data for Block BB
Block BB Net area 5105 m^2
Residential
Residential area of Block BB: 100 % of
total
Units with Comfort cooling 0
Affordable units:80
Electricity use 40 kWh/m2 /year
Gas use 80 kWh/m2 /year
Energy demand for the residential area: 612600 kWh/year
Total energy demand for Block BB 612600 kWh/yearTable 10 showing technical data for block BB
B9.9 Technical Data for Block AA
Block AA Net area 3030 m^2
Residential
Residential area of Block AA: 100 % oftotal
Units with Comfort cooling 26
Affordable units:8
Electricity use 40 kWh/m2 /year
Electricity use 50 kWh/m2 /year [
Gas use 80 kWh/m2 /year
Energy demand for the residential area:386770 kWh/year
Total energy demand for Block AA 386770 kWh/yearTable 11 showing technical data for block AA
From the tables above the energy demand is set to 13000 (MWh/year).
The thermal demand is then estimated to 8500 MWh/year and the electrical demand
to 4500 MWh/year.
The demands are roughly 35 % electrical and 65% thermal for the Lots Road site. In
the report the Lots Road site is refereed to as a residential site for simplicity.
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B10 Evaluation calculations
Here are the calculations that are shown in section 5.1 on page 26 of the report in
table 1 the energy system matrix. The energy system matrix shows the system size
and energy output for different energy systems when achieving 50 % carbon dioxide
reduction at Lots Road site. It is also showing notes about the energy systems such asworking hours per year and coefficient of performance.
Energy system investigations shows that utilizing a single renewable energy to reach
the 50% CO2 reduction is difficult without wasting energy or sizing the system
incorrectly.
B10.1 Wind power
The carbon dioxide emission conversion factor for electricity is 0.422 (kgCO2 / kWh)and is used to get the energy output needed for wind power.
50 % carbon dioxide reduction per year is 2,000,000 kg CO2 / year
This equals the energy output of:
(2,000,000 / 0.422) = 4740.0 MWh/year Equation (46)
It is verified by earlier CO2 reduction calculations:
(50/27.43) x 2600 = 4740.0 MWh/year Equation(47)
From proven engineering [23] a 15 kW wind turbine will have a rotor blade of 9
meter with a 15 meter tower.
Using the rule of thumb of 30 % turbine efficiency [11], the power output for one 15
kW wind turbine equals to:
1500 x 365 x 24 x 0.3 = 39420 kWh/year Equation (48)
This means in order to achieve a 50 % reduction there will have to be 120 wind
turbines on the Lots road site.
B10.2 Biomass
The carbon emission conversion factor to get the energy output needed for biomass is
0,194 (kgCO2 / kWh). That is the carbon dioxide emission factor for heating with
natural gas.
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50 % carbon dioxide reduction per year is 2,000,000 kg CO2 / year
This equals the energy output of:
(2,000,000 / 0,194) = 10309.0 MWh/year Equation(49)
The efficiency from gas boilers is assumed to be 0.78 [24] so biomass will have to
deliver.
0.78 x 10309 = 8041.0 MWh /year Equation (51)
It is verified by earlier CO2 reduction calculations:
(50/16.166) x 2600 = 8041.0 MWh/year Equation(50)
The biomass boiler is assumed to work for 2200 hr/year and is taken from a Hoare
Lea Consulting internal [25] report. The system size then needs to be at least:
8041020 / 2200 = 3655 kW Equation (52)
B10.3 CHP
The conversion factors to get the energy output needed for CHP is 0,194 (kgCO2 /
kWh) for heating with natural gas and 0.422 (kgCO2 / kWh) for electricity.
50 % carbon dioxide reduction per year is 2,000,000 kg CO2 / year
Gas engine CHP will have an efficiency of 80% and a power to heat ratio of 1:1.286
[8].
When the CHP engine is assumed to a 2133.8 kW system in order to run for 5000
hours [25] the energy output will be:
2133.8 x 5000 + 2133.8 x 5000 x 1.286 = 24390.2 MWh/year Equation(53)
It is verified by earlier CO2 reduction calculations:
(50/5.33) x 2600 = 24390.2 MWh/year Equation(54)
The carbon emission reduction for a year is then:
((10669400 x 0.422) + (13720846/0.78) x 0.194)) – ((24390246/0.80) x 0.194)
= 2000473 kgCO2 / year Equation (55)
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B10.4 Biomass CHP
The conversion factor to get the energy output needed for biomass CHP is 0,194
(kgCO2 / kWh) for heating with natural gas and 0.422 (kgCO2 / kWh) for electricity.
50 % carbon dioxide reduction per year is 2,000,000 kg CO2 / year
The biomass CHP will have an efficiency of 80% and a power to heat ratio of 1:1.286
assumed same as for the CHP engine. [8]
When the biomass CHP engine is assumed to a 550kW system and to run for 5000
[25] hours the energy output will be:
539.3 x 5000 + 539.3 x 5000 x 1.286 = 6164.2 MWh/year Equation (56)
It is verified by earlier CO2 reduction calculations:
(50/21.09) x 2600 = 6164.1 MWh/year Equation(57)
The carbon emission reduction for a year is then:
(( 2696500 x 0.422) + (3467699/0.78 x 0.194))
= 2000401 kgCO2 / year Equation (58)
B10.5 Solar water heating
The conversion factor to get the energy output needed for solar water heating is 0,194(kgCO2 / kWh). That is the carbon dioxide emission factor for heating with natural
gas.
50 % carbon dioxide reduction per year is 2,000,000 kg CO2 / year
This equals the energy out put of:
(2,000,000 / 0,194) = 10309.0 MWh/year Equation (59)
The efficiency from the gas boilers is assumed to be 0.78 [10] solar water heating
panels then have to deliver:
0.78 x 10309 = 8041.0 MWh/year Equation (60)
It is verified by earlier CO2 reduction calculations:
(50/16.166) x 2600 = 8041.0 MWh/year Equation(61)
The energy output for solar water heating panel is assumed to 454 kWh / (yr * m2)
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This equals a system physical size of:
8041020 / 454 = 17711 m2
panel Equation(62)
B10.6 Photovoltaic
The conversion factor to get the energy output for PV electricity is 0.422 (kgCO2 /
kWh). That is the carbon dioxide emission factor for electricity from the grid.
50 % carbon dioxide reduction per year is 2,000,000 kg CO2 / year
This equals energy out put of:
(2,000,000 / 0.422) = 4740.0 MWh./year Equation(63)
It is verified by earlier CO2 reduction calculations:
(50/27.43) x 2600 = 4740.0MWh/year Equation(64)
System efficiency of 15 % means that 8 m2
of panel delivers one 1 kWp which equals
approximately 750 kWh per year [4].
The system physical size will then be:
(47393000 / 750) x 8 = 50553 m2
panel Equation (65)
B10.7 Ground source heating
The conversion factor to get the energy output needed for GSH is 0,194 (kgCO2 /
kWh) for heating with natural gas and 0.422 (kgCO2 / kWh) for electricity from the
grid.
The coefficient of performance is assumed to 4.
For the ground source heating system to save 2,000,000 (kg CO2 per year) the system
will have to deliver roughly14,000 MWh/year.
It is verified by earlier CO2 reduction calculations:
(50/9.31) x 2600 = 13963.5 MWh/year Equation(66)
The carbon emission reduction for a year is then:
(13963500/0.78 x 0.194) – ((1/4) x 13963500 x 0.422)
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= 2000000 kg CO2 / year Equation(67)
The system size will have to be 9309 kW and it will be operating 1500 hours per year.
The estimated operating hours is from a Hoare Lea internal report [10].
9309 x 1500 = 13963500 MWh/year Equation(68)
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Appendix B List of Figures
Figure 1 Excerpts from the Mayors energy strategy ............. ............. ............ .............. ............. ............ 182 Figure 2 The Mayors energy hierarchy ................................................................................................ 182 Figure 3 Sustainable design factors ...................................................................................................... 183 Figure 4 Excerpt from Part L1A ........................................................................................................... 184 Figure 5 Excerpt from Part L ............ .............. ............. ............. ............. .............. ............. ............ ........ 185
Appendix B List of Tables
Table 1 Ccost per kilowatt or square meter of the energy technologies ........................ .............. ......... 173 Table 2 Showing cost for energy systems. ........................................................................................... 173 Table 3 showing technical data for block JJ ......................................................................................... 187 Table 4 showing technical data for block HH ...................................................................................... 188 Table 5 showing technical data for block GG ...................................................................................... 188 Table 6 showing technical data for block FF........................................................................................ 189 Table 7 showing technical data for block EE ....................................................................................... 189 Table 8 showing technical data for block DD ...................................................................................... 190 Table 9 showing technical data for block CC ....................................................................................... 190 Table 10 showing technical data for block BB ..................................................................................... 191 Table 11 showing technical data for block AA .................................................................................... 191
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Appendix B References
[1] Hoare Lea Consulting [Verbal Source], Hoare Lea Consulting, Bristol, 2007
[2] Hoare Lea Consulting [Verbal Source], Hoare Lea Consulting, Bristol, 2007
[3] Hoare Lea Consulting [Verbal Source], Hoare Lea Consulting, Bristol, 2007
[4] Maunsell F, London Renewables Integrating renewable energy into new developments: Toolkit for
Planners, developers and consultants, London, Greater London Authority, 2004, p.52,
ISBN:1852616601
[5] Maunsell F, London Renewables Integrating renewable energy into new developments: Toolkit for
Planners, developers and consultants, London, Greater London Authority, 2004, p.41,
ISBN:1852616601
[6] BRE, SAP 2005:The Government´s Standard Assessment Procedure for Energy Rating of
Dwellings, Watford, DEFRA, 2005, p.67
[7] BRE, SAP 2005:The Government´s Standard Assessment Procedure for Energy Rating of
Dwellings, Watford, DEFRA, 2005, p.42
[8] Action energy, Good Practise Guide Combined heat and power in buildings, England, Carbon
Trust, 2004, p.04
[9] Maunsell F, London Renewables Integrating renewable energy into new developments: Toolkit for
Planners, developers and consultants, London, Greater London Authority, 2004, p.162-175,
ISBN:1852616601
[10] Hoare Lea Consulting [Internal Report], G C Bankside Energy Strategy Report For Planning
Submission, Hoare Lea Consulting, 2006.
[11] Energy Savings Trust [Home page on the Internet], Energy Savings Trust [Updated 2008, Cited
21-07-2007], Available from:
http://www.whatyoucando.co.uk/i/u/6024622/i/EST_factsheet_Small_wind.pdf
[12] BRE, SAP 2005:The Government´s Standard Assessment Procedure for Energy Rating of
Dwellings, Watford, DEFRA, 2005, p.67
[13] Hoare Lea Consulting [Internal Report], Architectural Drawings of the Lots Road Site, Hoare Lea
Consulting, 2001
[14] Office Of The Deputy Prime Minister, The building regulations 2000 Approved Documents L1A
New Dwellings 2006 Edition, ODPM, 2006, p. 16-21, ISBN:139781859462171
[15] Mayor of London, Green light to clean power The Mayor´s Energy Strategy, London, Greater
London Authority, 2004, p.47-48.
[16] Mayor of London, Green light to clean power The Mayor´s Energy Strategy, London, GreaterLondon Authority, 2004, p. X.
[17] Mayor of London, Green light to clean power The Mayor´s Energy Strategy, London, Greater
London Authority, 2004, p. XIII-XIV.
[18] Mayor of London, Supplementary Planning Guidance: Sustainable Design and Construction The
London Plan Supplementary Planning Guidance, London, Greater London Authority, 2004, p. 6.
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[19] Mayor of London, Supplementary Planning Guidance: Sustainable Design and Construction The
London Plan Supplementary Planning Guidance, London, Greater London Authority, 2004, p. 15.
[20] Office Of The Deputy Prime Minister, The building regulations 2000 Approved Documents L1A
New Dwellings 2006 Edition, ODPM, 2006, p. 5, ISBN:139781859462171
[21] Office Of The Deputy Prime Minister, The building regulations 2000 Approved Documents L1A
New Dwellings 2006 Edition, ODPM, 2006, p. 15, ISBN:139781859462171
[22] Office Of The Deputy Prime Minister, The building regulations 2000 Approved Documents L1A
New Dwellings 2006 Edition, ODPM, 2006, p. 16-21, ISBN:139781859462171
[23] Proven Energy, Health and Safety Information for Installation of Proven Wind Turbines in Public
Areas, Scotland, Proven Energy, 2003
[24] BRE, SAP 2005:The Government´s Standard Assessment Procedure for Energy Rating of
Dwellings, Watford, DEFRA, 2005, p.42
[25] Hoare Lea Consulting [Internal Report], G C Bankside Energy Strategy Report For Planning
Submission, Hoare Lea Consulting, 2006.