Ecohomes
From Building for a Future Spring 2004
The first question is “what impact EcoHomes will really have on the long-term sustainability of the housing stock of this country”. Although EcoHomes, strictly speaking, is an environmental assessment rather than a ‘sustainability’ assessment, the narrow view of environmental impact must be expanded and become rather more sophisticated if we are to achieve the long-term goal of sustainable development.
Considering that, prior to the introduction of EcoHomes, the only consistent and significant nod to environmental issues was via Part L of the Building Regulations. Therefore, any widespread environmental assessment method has got to be some kind of progress. However, a number of significant issues have been raised as sources of discussion, and this article will attempt to resolve the significance of these and ways in which they could be resolved. These issues are:
1. Can EcoHome dwellings really be called ‘sustainable’?
2. Is there a more effective way to introduce sustainability into the construction process?
3. Will EcoHomes be a negative driver where established sustainable concepts, fail to score points?
4. Is it economically viable to attempt to gain an ‘Excellent’ EcoHomes rating?
5 How will EcoHomes apply to the existing housing stock?
I will attempt to answer these and other questions in this article.
Questions have also been raised as to how valid a measure of sustainability the eco-profiling system is – the ecoprofiling system forms the basis of the Green Guide to Housing Specification, the document which feeds into the Materials section of EcoHomes. This issue is discussed in the section entitled Eco-profiling.
Background to the scheme
EcoHomes follows the pattern of the tried and tested BREEAM for Offices assessment. There are seven sections relating to environmental impacts: Energy, Transport, Pollution, Water, Land Use and Ecology, and Health and Well-being. Within each section are further issues e.g. within Energy there is Carbon Dioxide Emissions, Building Envelope (i.e. insulation standards), Drying Space etc. Each of these issues is worth one or more ‘credits’, which can be achieved if certain criteria are met. A weighting factor is applied to each section to give an overall score out of 100. (One complication of this is that each credit is not worth an equal amount, varying between 0.48% (Materials) and 2.14% (Pollution)). The overall score dictates a rating of ‘Pass’, ‘Good’, ‘Very Good’ or ‘Excellent’. Over 70 achieves an ‘Excellent’.
Confused? There is no doubt it is baffling at first but if you want an EcoHomes rating for your development, you either:
* Download and read very carefully the EcoHomes Guidance document from the BRE website (and keep a day free in your diary... I’m not joking, it is a very big document),
* Enlist for training from BRE, or commission a licensed assessor for guidance, and at as early a stage as possible.
Don’t expect to gain credits just by, for example, installing a few bike stands in the pavement, and putting a few rainwater butts around the place. If you think your assessor will turn a blind eye to the flat in the corner with poor daylighting, forget it.
This brings us to the complicated mechanics of getting an assessment. BRE produce a document called the Developer Sheets. This is designed to enable someone with no knowledge of EcoHomes to apply – it provides tickboxes and tables to be completed, and lists the documentation which must be submitted in order to achieve credits. This document is also provided to all licensed assessors (there are an ever increasing number of assessor organisations across the UK, for a list visit www.breeam.org). The assessor will issue a ‘certification report’ to BRE. A quality assurance process is carried out by BRE, and then BRE issue the certificate for the appropriate rating.
Collating the information to enable certification can be a time-consuming process and should not be underestimated. With planning and suitable guidance, an assessment can be completed in a period of a just few weeks, but in some cases it can take months or even years.
EcoHomes is intended to be applied at the design stage. The ideal programme to enable the optimum rating to be achieved would be:
* Refer to the EcoHomes criteria at the earliest possible stage, pre-plan, and consult with someone with experience or knowledge of EcoHomes, to ensure that the design can achieve sufficient credits
* Incorporate the relevant issues into the specification and drawings as they are produced – ensuring sufficient detail to demonstrate compliance with the EcoHomes criteria
* If necessary, obtain ongoing advice to ensure that design changes do not compromise the EcoHomes rating
* At a later stage when the design has been finalised, but well ahead of completion, collate the documentation for certification.
Where documentation is not available at the time of certification e.g. timber proof of origin, the BRE reserve the right to audit the documentation supplied post-certification. ‘Design and Build’ contracts can be a problem as it is often difficult to obtain documentary evidence demonstrating that measures are implemented according to the specification.
Post-construction reviews can be undertaken to ensure that the measures incorporated into the design are carried into the final build, although these are not compulsory and are currently rather infrequently carried out. English Partnerships have noted the importance of these reviews and now specify them for developments on their land (they generally require at least a Very Good rating).
A good way of ensuring EcoHomes credits are achieved is to incorporate measures into the specification e.g. following a specification review. This particularly makes sense when a standard specification is applied to a number of developments. Incorporating measures compliant with EcoHomes will ensure a target rating is achieved and also provides a valid source of documentary evidence.
It is proposed by BRE that EcoHomes will be updated every year – the latest version was issued in June 2003. The version in force when an assessment is registered with BRE will apply. These updates will hopefully take into account feedback received during the year, adapt to changing legislation, and ensure a continual rise in standards.
All dwellings listed on the certification application must meet the standard required i.e. each credit is awarded based on the worst-case dwelling with respect to that issue. The only exception is the carbon dioxide emissions and building envelope sections which are based on a weighted average value for the site. The site can be split into different ‘phases’ if desired – the definition of a ‘phase’ may need to be confirmed with BRE but flats and houses can usually be separated if required (the certificate must make clear which dwellings are assessed).
Bespoke EcoHomes assessments are applied by BRE where a development is not purely residential, or is a special case such as sheltered accommodation. Bespoke assessments are more in-depth and significantly more costly.
How much will an assessment cost? Licensed assessors will typically charge in the region of £1,500 for certification plus basic guidance, more for larger sites or if you require a high rating and consequently more in-depth guidance. Alternatively, anyone can be trained as an assessor - training is carried out by BRE: two days’ training is required plus the satisfactory completion of a test assessment. This currently costs £950 in total. To be a licensed assessor, you must also pay £350 per year as a licence fee. There are certification fees payable to BRE of £5 per dwelling (minimum £200 per assessment) to cover quality assurance and administration. (All fees are subject to VAT and, of course, subject to change.)
Sustainable measures ready reckoner
Let’s examine a range of sustainable measures which could be incorporated into the design of a residential dwelling, and consider how they would be likely to score under EcoHomes. It is important to remember that credits in different sections are not equally weighted and scores may vary depending on the design of the dwelling.
Passive solar design: You won’t get much for this, maybe one more credit for CO2 emissions. The reason is that the SAP calculation is not strongly affected by solar gain and, in addition, for new well-insulated homes, space heating is only a minor proportion of the overall CO2 emissions (lights and appliances being a dominant part).
Sunspaces: Zero additional credits are likely as sunspaces outside the thermal envelope do not strongly affect the SAP calculation, except for a small sheltering effect.
Wood-burning stoves: As wood is designated a renewable source of energy with zero carbon dioxide emissions, several additional credits can be achieved. NOx emissions may be high, however, which could cancel out any advantage over gas boilers.
Ground-source heat pumps (electric): As NOx emissions due to electricity from the grid are extremely high, zero credits will be achieved for NOx, regardless of the coefficient of performance of the heat pump. However, the CO2 emissions are comparable with a gas condensing boiler and therefore would be an improvement over standard electric heating.
Solar hot water heating: This typically achieves one extra credit for reduced CO2 emissions. As with the other previous issues, this relatively small benefit is a reflection of the SAP calculation - and the contribution assumed for the solar input - and also due to the high proportion of CO2 emissions from lights and appliances.
Photovoltaics: There is an opportunity to gain several credits from installing photovoltaics, as they are replacing electricity for lights and appliances with proportionally higher CO2 emissions than gas heating. The number of credits achieved will depend on the number and size of panels used.
CHP: The performance will be very variable depending on the system. On a mixed-use site with a high heat demand, the system can be sized to produce a large amount of electricity and could gain several credits. On a purely residential site with lower heat demand, less electricity will be produced and the performance will be nearer that of individual condensing boilers. NOx emissions may be higher than with a standard condensing boilers so performance may be reduced in the pollution section.
‘Green’ electricity from the grid: This is not awarded any additional credits because it is not a permanent or semi-permanent part of the dwelling.
Super-insulation: You will get five credits for the building envelope, although five credits can usually be achieved just by meeting best practice U-values as the baseline is the relatively lax ‘unadjusted’ Target U-value. (BRE propose to tighten this standard when the new Part L1 is issued in – if all goes to plan – 2005.) An additional credit may be achieved for improved carbon dioxide emissions.
Thermal mass: This will not generally gain any credits as the SAP calculation does not take thermal mass into account. You may be getting benefit when global warming kicks in and everyone else is plugging in their cooling units, but unfortunately this is not considered. You may also lose credits under materials as concrete tends to perform poorly. The one area you can perform well is for sound insulation, which can be improved above Building Regulations requirements (if you are having sufficient pre-completion testing).
Continues on page 2 
Author: Michael Priaulx
Refs.
FaberMaunsell: www.fabermaunsell.com
FaberMaunsell EcoHomes team:
www.ecde.co.uk/breeam/breeam_ecohomes
BRE EcoHomes: www.bre.co.uk/ecohomes - download the EcoHomes Guidance document and Developer Sheets, and also obtain a list of licensed EcoHomes assessors.
EcoHomes: the Environmental Rating for Homes – S Rao, A Yates, D Brownhill and N Howard (BRE 2000). Available from Construction Research Communications (CRC) tel. 020 7505 6622.
Green Guide to Housing Specification – Jane Anderson & Nigel Howard (BRE 2000). Also available from CRC.
Sustainable Homes: www.sustainablehomes.co.uk - download a ‘Guide to EcoHomes’ and lots of other useful information on sustainable housing.
Housing Corporation: www.housingcorp.gov.uk/resources/sustain
English Partnerships: www.englishpartnerships.co.uk - search for ‘environmental standards’ to view minimum development requirements.
Brampton EcoHouse: www.brampton-ecohouse.org.uk
(see also BFF Vol.10 No.2)
Galliford Try Group: www.gallifordtry.co.uk
Stock Woolstencroft: www.stockwool.co.uk
Toynbee Housing Association: www.toynbeeha.co.uk
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