i Evaluating the Sustainability Credentials of the Passivhaus Standard in Comparison to Traditional Construction Techniques David Michael Baines Submitted as Part Requirement for the B.A (Hons) degree in Civil Engineering at Newcastle University May 2012
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
i
Evaluating the Sustainability Credentials of the Passivhaus Standard
in Comparison to Traditional Construction Techniques
David Michael Baines
Submitted as Part Requirement for the
B.A (Hons) degree in Civil Engineering
at Newcastle University
May 2012
ii
Executive Summary
This report considers the requirement for sustainable homes and determines that fossil fuel depletion,
levels of carbon dioxide emissions and the increasing costs of energy are key issues. The UK is now a
net energy importer and the UK government is imposing increasingly stringent regulation on carbon
emissions and therefore ‘low energy’ housing is of increasing importance.
Studies show that newly constructed dwellings are under achieving in terms of thermal performance.
The causes of this under-performance are addressed in the Passivhaus standard.
Passivhaus is an energy standard that uses basic principles, such as air tightness, super insulation and
the removal of thermal bridges to vastly reduce a buildings energy demand. The construction
techniques used in Passivhaus show similarities to conventional construction methods, but with much
more stringent quality control measures and attention to detail. Through the use of the Passivhaus
Planning Package, it is claimed that specific heating demand can be reduced by up to 90%.
Through site visits and meetings with professionals involved with Passivhaus design, the UK’s first
carbon neutral office and a £8.7 million Passivhaus primary school have been used as case studies to
assess their sustainability credentials.
The relationship between Passivhaus and other environmental assessment methods, such as BREEAM
and the Code for Sustainable Homes has been assessed. The report concludes that Passivhaus is
narrow in its focus as it considers only energy efficiency in its approach to sustainability. However, this
does not restrict the implementation of other methods of improving sustainability, such as photo-
voltaic panels and wind turbines as well as other forms of renewable technologies.
Code for Sustainable Homes level 3 is current standard building practice in the UK. A cost comparison
has been carried out to compare the differences between this standard and Passivhaus. At present,
there is a Passivhaus cost uplift of around 15%, however, this cost difference could be decreased as
wide-spread adoption of Passivhaus takes place and the UK workforce becomes more familiar with its
design. A separate comparison of heat demand has been conducted and concluded that a Passivhaus
primary school can have a reduced heating demand of over 90% in comparison to other existing
schools.
The report also considers the disadvantages of the standard which include the cost uplift, the higher
levels of site supervision and quality control required, as well as the unavailability of certain
components in the UK marketplace.
iii
The report concludes that Passivhaus is a more sustainable solution compared to conventional
building. Although it focuses on energy saving only, this does not preclude it from other forms of
sustainable development. Passivhaus could be an important tool in the Government’s CO2 reduction
targets for 2050.
iv
Table of Contents
Executive Summary............................................................................................................................... ii
List of Tables and Figures ...................................................................................................................... v
Acknowledgements ............................................................................................................................. vi
Abbreviations ...................................................................................................................................... vi
Figure 11: Cost Comparison of Passivhaus and Code Level 3 Source: Bere:Architects
9.1.1 Cost Comparison
In assessing the sustainability of the Passivhaus standard it is important to consider the financial
aspects of the design. An experiment has
been carried out to compare the
construction costs of a code level 3
house, (which is equal to current
building regulation).and a Passivhaus.
The experiment was carried out by
Bere:Architects in Ebbw Vale, Wales.
Two houses of equal internal volume
were constructed to enable the
difference in construction costs to be
compared.
The study found that the total cost of Passivhaus construction was £96,677, taking 68 days to
complete. The total cost of the Code Level 3 house was £83,651, taking 70 days to complete. This
equates to an increased cost of around 15%. For the raw data used to form Figure 11 and refer to
Appendices Item 4.
0
2000
4000
6000
8000
10000
12000
14000
16000
18000
Co
st (G
BP
)
Cost Comparison of Passivhaus and Code Level 3
Passivhaus
Code Level 3
22
Chantry Middle School
Amble County Middle School
Horton Grange First School
Seaton Hirst C of E Middle School
Bellingham Community Middle School
Blyth Tynedale County Middle School
Bothal Middle School
Diamond Hall Junior School
Farringdon Primary School
Chilton Primary School
Langley Park Primary School
Richmond Hill Primary Passivhaus
Figure 11: Specific Heating Demand – Richmond Hill Primary School
9.2 Comparison of Specific Heating Demand 9.2.1 Richmond Hill Primary School
Data has been obtained from Display Energy Certificates to provide a comparison of Richmond Hill
Primary School to other schools of a similar size. Primary Schools in the North of England with a Gross
Internal Area (GIA) the same as Richmond Hill (+ / - 10%) have been selected as a comparison.
Figure 11 displays the results of this comparison;
It has been calculated using PHPP that Richmond Hill will have a heat demand of 13 kWh/m²/annum.37
The mean heat demand of the other primary schools is 184 kWh/m²/annum.
Refer to Appendices Item 5 for the raw data used to create this chart.
23
Essendine Primary School
Purley Oaks Primary School
Benthal Primary School
Burnt Ash Primary School
Commonswood Jmi School
Betty Layward Primary School
Caldecote Primary School
Montgomery Passivhaus
Figure 13: Specific Heating Demand – Montgomery Primary
9.2.1 Montgomery Primary School
Located in Exeter, Montgomery Primary School has a capacity of 450 students and achieved
Passivhaus accreditation in February 2012.
Figure 13 shows a comparison between Montgomery School and other schools across the UK with the
same number of students.
It has been calculated using the PHPP that Montgomery Primary will have a heat demand of 15
kWh/m²/annum. The mean heat demand of the other primary schools is 152 kWh/m²/annum.
In conclusion, the mean energy demand of the two Passivhaus School’s is 14 KWh/m²/annum.
The mean energy demand of all of the non-Passivhaus school’s is 172 KWh/m²/annum..
This shows a difference in energy demand of almost 92%.
24
10.Disadvantages:
One of the most obvious disadvantages of adopting the Passivhaus standard is the cost uplift. The
Passivhaus Institute state the cost uplift is around 7%, however, results analysed during this report
have concluded costs could be increased by as much as 15%. However, the large savings in energy
costs mean that the payback period is relatively short.
After meeting with the project manager during the construction of Richmond Hill Primary School,
there were several draw backs that he encountered;
- More site management is required with greater levels of supervision and guidance. Quality
control is of upmost importance and a large amount of photographic evidence was required to
provide proof of correct procedures. Inspections carried out on a regular basis.
- Increased complexity of design details required a full time, site based design manager, adding
to staffing costs.
- Mistakes made during construction are difficult to rectify without first considering how any
changes could affect the stringent air tightness standards.
- Passivhaus construction generally requires more time than traditional methods. Construction
programme estimated to be around 6 weeks longer (adding around 10% onto total
construction time) compared to traditional construction methods.
The Architect involved on Richmond Hill Primary School commented;
- There is a lack of knowledge of the Passivhaus standard, particularly with the fitting of services
as this is the area that most differs from conventional construction.
- Larger requirement for a fully collaborative team and communication.
- UK manufacturers are slow to adapt to what is required in terms of verification of
performance, which is much more stringent for Passivhaus. The availability of suppliers is
limited and as such could lead to less competitive tendering. “This is fundamental for wide
adoption of Passivhaus, Austria for example, have government funded accreditation for their
‘home grown’ suppliers and manufacturers and as such can now build to Passivhaus standard
at no extra cost” Space Architects, 2012
There is a danger of the term “Passivhaus” being used to describe dwellings that have been designed
to be more energy efficient and indeed include some of the Passivhaus principles, however, have not
achieved official Passivhaus accreditation.
25
A study published by the University of Dublin, “Defining Zero Energy Buildings – A Life Cycle
Perspective”, determined that in order to achieve the last unit of KWh/m² reduction required to meet
the Passivhaus standard the embodied energy of the building was increased and the reduction in
energy consumption achieved was counter-balanced. This suggests that the 15KWh/m² requirement
could be too stringent and that better overall results could be achieved with a slightly less stringent
requirement.
Passivhaus is dependent upon mechanical ventilation. Business development manager at Interserve’s
Leicester office suggested that some members of the public feel that the air tightness and reliance on
MVHR systems can make them feel uncomfortable and / or claustrophobic and may believe that it
could have negative side effects on health.
Research conducted by the National House Building Council (NHBC) in 2009 identified a range of
studies from the UK and other countries which point to a link between Indoor Air Quality (IAQ) and
health of occupants. “Evidence from a few studies points to the fact that, working correctly, MVHR is
able to have a positive effect on IAQ and health, but clearly this can only be expected to be realised in
practice if the system is functioning correctly.”38
On the whole, very few criticisms of the Passivhaus standard have been found. Although Passivhaus is
increasing in popularity; relatively little has been published on the subject. While conducting research
for this report, an effort has been made to obtain information that is unbiased and represents an
honest depiction of the Passivhaus standard. However, it is important to note that some of the
professionals questioned throughout the formation of this report are actively involved in the
promotion of Passivhaus and may have financial incentives for Passivhaus to increase in popularity.
26
11.Discussion
From the data analysed in the formation of this report, it appears that Passivhaus offers a much more
sustainable solution to building than the current building regulations and it can be expected to
increase in popularity in the foreseeable future.
The experiences of construction manager, Bill Butcher, responsible for the construction of Denby Dale
Passivhaus, West Yorkshire, have led him to believe that “Passivhaus is the way forward for the UK. It
can help create quality, comfortable buildings while also achieving 90% cuts in occupants’ fuel bills. It
offers the UK an easy win solution towards the massive cuts in CO2 emissions we need to make -
urgently.”39
Currently, Passivhaus is more expensive to construct than traditional / main stream techniques.
However, the UK is currently experiencing a ‘Passivhaus learning curve’ where many difficulties
currently experienced can be rectified through gaining familiarity with the Passivhaus standard which
will increase the efficiency of construction while decreasing the time and costs.
There are many alternatives to the Passivhaus standard. So-called ‘green buildings’ have energy
usages that are largely unknown. Their performances are not often measured and often poorly
modeled using Standard Assessment Procedures (SAP), therefore ‘zero carbon’ and ‘low energy’
buildings are being built with no official certification. The PHPP offers an absolute measure and
provides the users with clear results. It is capable of determining what effect particular changes will
have on the end result. Other sustainability standards, for example, the Code for Sustainable Homes is
not so clear in its operation. A large amount of variation is allowed whereas the Passivhaus limitation
of 15 kWh/m²/annum is clear and final.
It is not possible to state which method of eco-friendly building is superior. Different methods have
their merits and criticisms and the most sustainable solution could be a combination of different
methods, depending on the individual circumstance of the build.
27
Within the Approved Document L 2013, a proposal has been made to set a dwellings fabric efficiency
target (DFEE). The DFEE is expressed as kWh/m²/annum which correlates directly with the unit
measurement used for Passivhaus projects. The figures proposed for 2016 (taken from the zero
carbon hub) are 39kWh/m²/annum for apartments and mid-terraced houses and 46kWh/m²/annum
for end terrace, semi detached and detached properties. The Passivhaus’s requirement is
15kWh/m²/annum and will therefore result in much greater energy savings.
Location is an important factor in the performance of a Passivhaus. A study by the ‘Promotion of
European Passive Houses’ entitled ‘Energy Saving Potential’ highlighted that the figures related to the
Passivhaus’ ability to reduce energy consumption must be considered specific to each country.
In the UK, “the total primary energy use of a Passive House is 32% of that of an existing dwelling.
Compared to a typical new dwelling, a Passive House in the UK shows a total primary energy use of
41% and an energy use for space heating of 23%. In both cases a reduction of energy use for domestic
hot water of 50% is expected”40 Promotion of European Passive Houses, 2006
28
12.Conclusions and Recommendations
Although sustainability is comprised of many areas, energy demand is arguably the most important
and pressing issue that needs acting upon. It is not possible to sustain the current upward trend in
levels of energy use in buildings and modern buildings are not meeting their stated energy
performance targets.
There are many key areas that are considered when assessing the sustainability of a building, including
energy / CO2, water, materials, waste, pollution, health and well-being, management and ecology.
Although Passivhaus focuses upon maximising energy efficiency and could not be considered a holistic
approach, it does not detract from any of these other key areas. It provides an excellent base from
which other sustainability driven technologies can be applied.
Construction of a Passivhaus requires meticulous attention to detail where great importance is placed
upon insulation, air tightness and thermal bridging. The case studies in this report suggest that the UK
workforce is capable of adapting to the differences in design and the increased quality control
procedures.
The Passivhaus institute claim that “Passive Houses allows for energy savings of up to 90% compared
with typical Central European buildings stock and over 75% compared to average new
builds”41Passivhaus Institute, 2012.
Analysing the results of the display energy certificates for schools and comparing them to Richmond
Hill and Montgomery Primary Schools, energy demand has been reduced by approximately 92%. This
suggests that there is truth behind the Passivhaus Institute’s claims of achieving 90% energy
reductions on existing buildings.
BRE acknowledge that the carbon emissions target of 2050 is not achievable as things stand.
Suggestions have been made of implementing code for sustainable homes level 6 immediately in
order to improve the carbon emissions performance. However, Passivhaus has demonstrated that it
could have major part to play and potentially be a better alternative in reducing CO2 emissions.
Many people will be unclear on what an ‘eco-home’ consists of as other sustainability standards are
not easily defined and are not easily modelled. Through the use of the PHPP, consumers can be clear
on what design parameters they are trying to achieve as Passivhaus is focused with set aims. It is not
prescriptive in how the targets are met and leaves the methods of achieving the targets to personal
preference, dependant on the individual case. For this reason it is easily defined and understandable.
29
This study has shown that Passivhaus is much more sustainable than current building standards
construction and could be considered to have an important part to play in the government’s target to
reduce CO2 emissions.
30
References 1 Why Sustainability is Important. Sustainable Housing Foundation. [Online] [Cited 3rd March 2012] http://www.sustainablehousingfoundation.com/about-shf/why-is-sustainability-important/ 2 Energy Imports and Exports. Paul Bolton. [Online] [Cited 20th April 2012] http://www.parliament.uk/briefing-papers/SN04046.pdf 3 Carbon Zero Homes Plan Unveiled. BBC News. [Online] [Cited 20
th April 2012]
http://news.bbc.co.uk/1/hi/sci/tech/6176229.stm 4 Budget 2011: Zero-carbon homes plan 'watered down. The Guardian. [Online] [Cited 20th April 2012] 'http://www.guardian.co.uk/uk/2011/mar/23/budget-2011-zero-carbon-homes 5 Energy Efficiency in New and Existing Buildings. BRE Trust.2010. [Cited 2nd May 2012] 6 Evaluating the Impact of an Enhanced Energy Performance Standard on Load – Bearing Masonry Domestic Construction. Leeds Metropolitan University. [Online] [Cite 26
th March 2012]
http://www.leedsmet.ac.uk/as/cebe/projects/stamford/pdfs/del8execsum.pdf 7 Evaluating the Impact of an Enhanced Energy Performance Standard on Load – Bearing Masonry Domestic Construction. Leeds Metropolitan University. [Online] [Cite 26
th March 2012]
http://www.leedsmet.ac.uk/as/cebe/projects/stamford/pdfs/del8execsum.pdf 8 The Passivhaus Standard. BRE. [Online] [Cited 3rd March 2012] http://www.passivhaus.org.uk/standard.jsp?id=37 9 Passive Solar House Design. Adamson 1987 and Fiest 1988. [Online] [Cited 2nd April 2012] http://www.creategreenhome.com/Passive_Solar.htm 10 Why Passivhaus Certification. Passivhaus Homes. [Online] [Cited 2nd April 2012] http://www.passivhaushomes.co.uk/whycertify.html
General Principles for Improving Airtightness. Passipedia. [Online] [Cited 2nd
April 2012] http://passipedia.passiv.de/passipedia_en/planning/airtight_construction/general_principles/principles_for_improving_airtightness 13
Thermal Bridges. Passipedia. [Online] [Cited 2nd
April 2012] http://passipedia.passiv.de/passipedia_en/basics/building_physics_-_basics/heat_transfer/thermal_bridges 14 U values. John Brenan. [Online] [Cited 2
Information gathered from Billinghurst George and Partners, Meeting held 2nd
May 16 Interserve. UK Construction Magazine. [Online] [Cited 2nd May 2012] http://www.ukconstructionmagazine.co.uk/online/uk_construction/uk_features/april2012/interserve.html 17 Information obtained via email from Business Development Manager, John Walkerdine, Interserve Construction Ltd, March 2012
31
18 Interserve to Deliver Passivhaus Certified Leeds School. Interserve Plc. [Online] [Cited 2nd May 2012] www.interserve.com/news-media/press-releases-and-news/2011/10/25/1657/interserve-to-deliver-passivhaus-certified-leeds-school 19 Anecdotal, PM Richmond Hill, Jim Shaw, Interserve Construction Ltd, February 2012 20
The Building Schools for the Future Programme: Renewing the Secondary School Estate. National Audit Office. [Online] [Cited 20
th April 2012]
http://www.nao.org.uk/publications/0809/schools_for_the_future.aspx 21 What is BREEAM? BREEAM. [Online] [Cited 20th April 2012] http://www.breeam.org/page.jsp?id=66 22 Code for Sustainable Homes. BREEAM. [Online] [Cited 20th April 2012] http://www.breeam.org/page.jsp?id=86 23
Code for Sustainable Homes. Communities and Local Government. [Online] [Cited 21st
April 2012] http://www.communities.gov.uk/planningandbuilding/sustainability/codesustainablehomes/ 24
Lighthouse – Home Page. Kingspan. [Online] [Cited 21st
April 2012] www.kingspanlighthouse.com 25 Code for Sustainable Homes: Case Studies. Communities and Local Government. [Online] [Cited 21st April 2012] http://www.communities.gov.uk/publications/planningandbuilding/codecasestudies 26 Code for Sustainable Homes: Case Studies. Communities and Local Government. [Online] [Cited 21st April 2012] http://www.communities.gov.uk/publications/planningandbuilding/codecasestudies 27 Passivhaus Project Reveals Flaws in Code. Green Building Store. [Online] [Cited 21st April 2012] http://www.greenbuildingstore.co.uk/news--passivhaus-code-for-sustainable-homes.html 28 Passivhaus Project Reveals Flaws in Code. Green Building Store. [Online] [Cited 21st April 2012] http://www.greenbuildingstore.co.uk/news--passivhaus-code-for-sustainable-homes.html 29
Passivhaus Project Reveals Flaws in Code. Green Building Store. [Online] [Cited 21st
April 2012] http://www.greenbuildingstore.co.uk/news--passivhaus-code-for-sustainable-homes.html 30
Tarmac House. The University of Nottingham. [Online] [Cited 26th
April 2012] www.nottingham.ac.uk/~lazwww/creative_energy_homes/tarmac/index.html 31
Is Solar Power a Bright Investment? The Guardian. [Online] [Cited 26th
April] http://www.guardian.co.uk/money/2010/feb/06/solar-power-bright-investment 32 South Tyneside Local Development Framework. South Tyneside Council. [Online] [Cited 26th April 2012] http://www.southtyneside.info/CHttpHandler.ashx?id=3172&p=0 33 Anecdotal, information gathered from structural designer, Billinghurst George and Partners, March 2012 34 World Commissions on Environment and Development (1987:23). 35 What is Passivhaus? CEADA. [Online] [Cited 15th April 2012] http://www.ceada.co.uk/our-service/passivhaus/ 36 Anecdotal – Project Manager at Richmond Hill, Jim Shaw, Interserve Construction Ltd, March 2012. 37
Quote from Architect. David Savage, Space Architects, March 2nd
2012-05-08
32
38 Mechanical Ventilation with Heat Recovery in New Homes. Zero carbon Hub. [Online] [Cited 3
rd May 2012] ,
January 2012 http://www.zerocarbonhub.org/resourcefiles/ViaqReport_web.pdf 39
Passivhaus Diaries, Part 20: Coming to an End. Bill Butcher. [Online] [Cited 3rd
may 2012] http://www.building.co.uk/passivhaus-diaries-part-20-coming-to-an-end/3159554.article 40 Energy Saving Potential. Promotion of European Passive Houses. [Online] [Cited 3rd May 2012] http://www.rockwool.com/files/rockwool.com/Energy%20Efficiency/Library/EnergySavingPotential.pdf 41
What is a Passivhaus? Passivhaus Institute. [Online] [Cited 4th
May 2012] http://www.passiv.de/en/02_informations/01_whatisapassivehouse/01_whatisapassivehouse.htm
33
Appendices
Item 1.1 : Architects details of construction methods
34
Item 1.2
Item 1.3
35
Item 1.4:
Item 1.5 :
36
Item 2.1: Energy Performance Certificates for Interserve Old Leicester Office.
This building achieved a G rating, meaning that it the building’s thermal performance was very poor
and the heat demand, especially during winter, would have been very high.
37
Item 2.2: Energy Performance Certificate for Interserve New Leicester Office
38
Item 3:
An example of one the differences between Richmond Hill and non-Passivhaus schools is the attention
paid to the reduction of thermal bridging at foundation level where at Richmond Hill foam glass bloack
where introduced between the pile caps and steel column foundation.
39
Item 4.1: Raw Data for Ebbw, Wales Passivhaus Cost Comparison