An Energy Strategy for a Residential Scheme in London

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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



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.



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.



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



IV

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



V

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



1

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.



2

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.



3

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.



4

Methodolgy Flow Diagram

Energy Demand Assessment

CO2 Emission Assessment

Energy System Studies

Site Examination

Final Recommendation

System Configuration

Figure 1 methodology flow diagram



5

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.



6

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



7

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



8

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.



9

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.



10

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.



11

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



12

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.



13

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.


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


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.




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.


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]



14

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


energy systems. The capital cost for implementing biomass CHP is then £ 380, 800.





15

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.


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.




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.


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.



16

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


energy systems. The capital cost for implementing CHP is then £ 180, 000.





17

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.


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%.




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.


Investigation for GSH to obtain planning permission when being implemented on the Lots


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.



18

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


energy systems. The capital cost for implementing GSH is then £ 900, 000


appendix B5.3 on page 173



19

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.


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%.



.


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.



20


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


energy systems. The capital cost for implementing PV is then £ 13, 600, 000





21

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.


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%.




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.


Investigation for SWH to obtain planning permission when being implemented on the Lots


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.



22

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


energy systems. The capital cost for implementing SWH is then £ 1, 200, 000.





23

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.


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





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.


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.



24

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


energy systems.. The capital cost for implementing wind power is then

£ 1, 140, 000





25

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.



26

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



27

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.



28

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.



29

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



30

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



31

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



32

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



33

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.



34

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.



35

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.



36

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.



37

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.



38

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.



39

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



40

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



41

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.



42

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



43

Figure 11 Top view of block HH

Figure 12 Left side view of block HH



44

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.


provide energy to block GG. Obstacles are that CHP is more favourable when there is a high




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.



45

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



46

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.


provide energy to block FF. Obstacles are that CHP is more favourable when there is a high






47

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



48

Figure 19 Top view of block FF

Figure 20 Left side view of block FF



49

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



50

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



51

Figure 24 Back view of block EE



52

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



53

Figure 27 Top view of block DD

Figure 28 Back view of block DD



54

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



55

Figure 31 Top view of block CC

Figure 32 Back view of block CC



56

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



57

Figure 35 Top view of block BB

Figure 36 Back view of block BB



58

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



59

Figure 39 Top view of block AA

Figure 40 Back view of block AA



60

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]



62

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.



63

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



66

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.



69

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


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.



75

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



76

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



77

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.



78

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 .



79

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.



81

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.



84

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



85

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



86

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



87

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.



88

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.



89

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



90

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



91

References

[1] Union of Concerned Scientists [Home page on the Internet], Union of Concerned Scientists [Updated 21-05-

2007, Cited 21-06-2007], Available from: http://www.ucsusa.org/global_warming/science/

[2] BBC [Home page on the Internet], BBC [Cited 22-06-2007], Available from:

http://news.bbc.co.uk/1/shared/spl/hi/sci_nat/04/climate_change/html/greenhouse.stm

[3]Town And Country Planning Association, Sustainable energy by design a TCPA `by design´ guide for

sustainable communities, London, TCPA, 2006, p. 02-05, ISBN:0902797395

[4] Office Of The Deputy Prime Minister, The building regulations 2000 Approved Documents L1A New

Dwellings 2006 Edition, ODPM, 2006, p. 16-21, ISBN:139781859462171

[5] Maunsell F, London Renewables Integrating renewable energy into new developments: Toolkit for Planners,

developers and consultants, London, Greater London Authority, 2004, p. 07, ISBN:1852616601

[6] Hoare Lea Consulting [Internal Report], Architectural Drawings of the Lots Road Site, Hoare Lea

Consulting, 2001

[7] Hoare Lea Consulting [Internal Report], Lots Road 2001 stage 3 Design Report , Hoare Lea Consulting, 2001

[8] Hoare Lea Consulting [Internal Report], G C Bankside Energy strategy Report For Planning Submission,

Hoare Lea Consulting, 2006, p.07

[9] Maunsell F, London Renewables Integrating renewable energy into new developments: Toolkit for Planners,

developers and consultants, London, Greater London Authority, 2004, p.107-109, ISBN:1852616601

[10] BRE, SAP 2005:The Government´s Standard Assessment Procedure for Energy Rating of Dwellings,

Watford, DEFRA, 2005, p.42

[11] BRE, SAP 2005:The Government´s Standard Assessment Procedure for Energy Rating of Dwellings,


[12] BRE, SAP 2005:The Government´s Standard Assessment Procedure for Energy Rating of Dwellings,Watford, DEFRA, 2005, p.67

[13] Maunsell F, London Renewables Integrating renewable energy into new developments: Toolkit for

Planners, developers and consultants, London, Greater London Authority, 2004, p.21-86, ISBN:1852616601

[14] Econergy[Home page on the Internet], Econergy[Cited 05-06-2007], Available from:

http://www.econergy.ltd.uk/downloads/Sheffield_Road%20Flats_case_study_470kW.pdf

[15] Action energy, Good Practise Guide Combined heat and power in buildings, England, Carbon Trust, 2004,

p.04

[16] Low Emission Bio ORC [Home page on the Internet], EESD [Cited 20-06-2007] Available from:

http://ec.europa.eu/energy/res/sectors/doc/bioenergy/chp/nne5_475_2000.pdf


Planners, developers and consultants, London, Greater London Authority, 2004, p.70, ISBN:1852616601

[18] Combined Heat and Power Association [Home page on the Internet], CHPA [Updated 01-01-2008, Cited

09-07-2007] Available from: http://www.chpa.co.uk/

[19] Combined Heat and Power Association [Home page on the Internet], CHPA [Updated 01-01-2008, Cited

09-07-2007] Available from: http://www.chpa.co.uk/

http://www.ucsusa.org/global_warming/science




http://www.chpa.co.uk/







http://www.ucsusa.org/global_warming/science



92


Planners, developers and consultants, London, Greater London Authority, 2004, p.72-78, ISBN:1852616601

[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


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,


[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

http://www.earthenergy.co.uk/case_studies/social_housing.php

http://www.sd-commission.org.uk/publications/downloads/Bronllys%20Hospital%20Solar%20Energy%20Project.pdf




http://www.ashdenawards.org/winners/barnsley

http://www.acicr.ualberta.ca/documents/HotWater2003PositionStatement.pdf

http://www.acicr.ualberta.ca/documents/HotWater2003PositionStatement.pdf

http://www.ashdenawards.org/winners/barnsley






http://www.earthenergy.co.uk/case_studies/social_housing.php



93

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.



94

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.



95

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.



96

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



97

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.



98

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].



99

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



100

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.



101

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



102

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



103

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



104

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].



105

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



106

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



107

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.



108

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



109

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.



110

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



111

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



112

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



113

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.



114

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



115

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



116

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]



117

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



118

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



119

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.

http://www.canren.gc.ca/





120

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)



121

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.



122

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.



123

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



124

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



125

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]



126

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



127

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.



128

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.



129

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.



130

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]



131

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



132

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



133

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



134

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].



135

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).



136

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.



137

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



138

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



139

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]



140

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



141

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



142

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



143

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]



144

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)



145

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



146

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



147

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.



148

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



149

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



150

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



151

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



152

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.



153

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



154

Advantages

• Energy savings through water recovery

Disadvantages

• Low cost efficiency

• Requires high maintenance to ensure sufficient system operation



155

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



156

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



157

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


Commission on environmental pollution, 2004, p. 09-29


Commission on environmental pollution, 2004, p. 30


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


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

http://www1.eere.energy.gov/biomass/pyrolysis.html#thermal

http://www1.eere.energy.gov/biomass/gasification.html


http://www.engineeringtoolbox.com/fuels-higher-calorific-values-d_169.html

http://www.bios-bioenergy.at/en/electricity-from-biomass/biogas.html

http://www.bios-bioenergy.at/en/electricity-from-biomass/biogas.html

http://www.engineeringtoolbox.com/fuels-higher-calorific-values-d_169.html


http://www1.eere.energy.gov/biomass/pyrolysis.html#thermal



158

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


characterization: Gas turbines, U.S., EPA, 2002, p.04


characterization: Steam turbines, U.S., EPA, 2002, p.04


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


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


Trust, 2004, p.04


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





159

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


Planners, developers and consultants, London, Greater London Authority, 2004, p.73,

ISBN:1852616601


Technical note, TN 18/1999, UK, 1999, p.07 figure 2.2



ISBN:1852616601


Technical note, TN 18/1999, UK, 1999, p.08 figure 2.3


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


Technical note, TN 18/1999, UK, 1999, p.04


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

http://www.heatpumpcentre.org/



http://www.skanska.co.uk/files/graphics/CFS/Datasheets/Energy%20Piles.pdf


http://www.ags.org.uk/aboutus/GeothermalEnergyandEnergyPiles.ppt

http://www.canren.gc.ca/app/filerepository/B0126630E3FD4FFD91D2FC21C213724C.pdf


http://www.nef.org.uk/gshp/documents/CE82-DomesticGroundSourceHeatPumps.pdf

http://www.nef.org.uk/gshp/documents/CE82-DomesticGroundSourceHeatPumps.pdf


http://www.canren.gc.ca/app/filerepository/B0126630E3FD4FFD91D2FC21C213724C.pdf

http://www.ags.org.uk/aboutus/GeothermalEnergyandEnergyPiles.ppt







160

SWH



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


[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




ISBN:1852616601



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



[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



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

http://www1.eere.energy.gov/solar/sh_basics_collectors.html#flatplate


http://www1.eere.energy.gov/solar/sh_basics_collectors.html#evacuatedtube



http://www1.eere.energy.gov/solar/solar_cell_materials.html

http://www.reuk.co.uk/40-Percent-Efficiency-PV-Solar-Panels.htm

http://www.greenenergy.org.uk/pvuk2/about/index.html

http://www.greenenergy.org.uk/pvuk2/about/index.html

http://www.reuk.co.uk/40-Percent-Efficiency-PV-Solar-Panels.htm




http://www1.eere.energy.gov/solar/sh_basics_collectors.html#evacuatedtube




161


from: http://www1.eere.energy.gov/solar/solar_cell_materials.html



[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



[12] DTI, Photovoltaic in Buildings, A design guide, UK, 1999, p.62


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


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



ISBN:1852616601



http://www1.eere.energy.gov/solar/pv_basics.html


http://www1.eere.energy.gov/solar/bos.html

http://www1.eere.energy.gov/solar/bos.html


http://www1.eere.energy.gov/solar/pv_basics.html





162

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


[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


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


[Cited: 11-06-2008] Available from: http://www.windpower.org/en/stat/betzpro.htm


[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


[Cited: 11-06-2008] Available from: http://www.windpower.org/en/stat/unitsw.htm#anchor1345942


[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


National marine aquarium, Bristol, 2005

[16] CIBSE, Guide A: Environmental Design, CIBSE, UK, p.28


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


National marine aquarium, Bristol, 2005


http://www.windpower.org/en/tour/wtrb/lift.htm

http://www.windpower.org/en/tour/wtrb/comp/index.htm

http://www.renewables-made-in-germany.com/fileadmin/user_upload/product/51/51_subimg1_web_web.jpg



http://www.windpower.org/en/tour/wtrb/electric.htm

http://www.windpower.org/en/stat/betzpro.htm

http://www.windpower.org/en/tour/wtrb/size.htm

http://www.windpower.org/en/stat/unitsw.htm#anchor1345942

http://www.windpower.org/en/tour/wres/weibull.htm



http://www.windpower.org/en/tour/wres/weibull.htm

http://www.windpower.org/en/stat/unitsw.htm#anchor1345942

http://www.windpower.org/en/tour/wtrb/size.htm

http://www.windpower.org/en/stat/betzpro.htm

http://www.windpower.org/en/tour/wtrb/electric.htm





http://www.windpower.org/en/tour/wtrb/comp/index.htm

http://www.windpower.org/en/tour/wtrb/lift.htm




163



ISBN:1852616601


[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


[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


[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

http://www.windpower.org/en/tour/econ/index.htm

http://www.greenpeace.org.uk/MultimediaFiles/Live/FullReport/3809.PDF

http://www.greenpeace.org.uk/MultimediaFiles/Live/FullReport/3809.PDF

http://www.windpower.org/en/tour/econ/index.htm



164

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





165

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)



166

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)



167

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.



168

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.



169

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].



170

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.


(1462642/0.78) x 0.194 + 1137358 x 0.4222= 843750.4 kgCO2 /year Equation(12)


(843750.4 /4000000) x 100 = 21.09 % Equation (13)



171

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.


((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.


(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.


(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.


(372366.7/4000000) x 100 = 9.31 % Equation (17)



172

B4.5 Photovoltaic

The photovoltaic system will deliver electricity and when delivering 20 % of the

yearly energy demand (2600 (MWh/year)).


2600000x 0.422= 1097200 kgCO2 /year Equation (18)


(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)


(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)).


2600000x 0.422 = 1097200 kgCO2 /year Equation (22)


(1097200/4000000) x 100 = 27.43 % Equation (23)



173

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.



174

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.


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.



175


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].


demand.

700 x 2200 = 1540000(kWh / year) Equation (28)



176

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].


demand.

140 x 5000 + 140 x 5000 x 1.286 = 1600000 (kWh / year Equation(30)



177

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.



178

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.


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.



179

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)



180

The savings for SWH for one year is 24450 £. SWH then have a payback time of 50

years.



181

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



182

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.





184

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



185

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



186

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.



187

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



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



188

B9.2 Technical Data for Block HH

Block HH Net area 9263m^2

Residential

Residential area of Block HH: 88% of

total


Affordable units:136



Energy demand for the residential area: 978172kWh/year

Retail

Retail area of Block HH: 12% of total


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


Affordable units:0



Energy demand for the residential area: 1596978.5kWh/yearRetail

Retail area of Block GG: 5% of total




Total energy demand for Block GG 1790296.95 kWh/yearTable 5 showing technical data for block GG



189

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



Energy demand for the residential area: 864129.5 kWh/yearRetail

Retail area of Block FF: 5% of total




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


Affordable units:0



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



190

B9.6 Technical Data for Block DD

Block DD Net area 4856 m^2

Residential

Residential area of Block DD: 100 % of

total


Affordable units:0




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


Affordable units:0




Total energy demand for Block CC 351780 kWh/yearTable 9 showing technical data for block CC



191

B9.8 Technical Data for Block BB

Block BB Net area 5105 m^2

Residential

Residential area of Block BB: 100 % of

total


Affordable units:80

Electricity use 40 kWh/m2 /year

Gas use 80 kWh/m2 /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


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.



192

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.



193


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)



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.


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)



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)



194

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.


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)




(( 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.


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)



The energy output for solar water heating panel is assumed to 454 kWh / (yr * m2)



195

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.


This equals energy out put of:

(2,000,000 / 0.422) = 4740.0 MWh./year Equation(63)


(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)


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.




(13963500/0.78 x 0.194) – ((1/4) x 13963500 x 0.422)



196

= 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)



197

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



198

Appendix B References






ISBN:1852616601



ISBN:1852616601

[6] BRE, SAP 2005:The Government´s Standard Assessment Procedure for Energy Rating of

Dwellings, Watford, DEFRA, 2005, p.67




Trust, 2004, p.04


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



[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.





[19] Mayor of London, Supplementary Planning Guidance: Sustainable Design and Construction The

London Plan Supplementary Planning Guidance, London, Greater London Authority, 2004, p. 15.


New Dwellings 2006 Edition, ODPM, 2006, p. 5, ISBN:139781859462171


New Dwellings 2006 Edition, ODPM, 2006, p. 15, ISBN:139781859462171


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



[25] Hoare Lea Consulting [Internal Report], G C Bankside Energy Strategy Report For Planning

Submission, Hoare Lea Consulting, 2006.