Sustainable Housing
Costing Sustainability
A comprehensive review carried out in California showed that ‘green’ buildings do not necessarily cost more to build, or if they do, can have short payback periods for the additional expenditure.
A study by BRE and Cyril Sweetts, Putting a price on sustainability, published in 2005, looked at the cost of reducing the environmental impacts of four building types, including housing. It also contradicts the perception that more sustainable design and construction solutions will incur substantial additional costs. The study looked at the costs of achieving the various EcoHome ratings and concluded that depending on the nature of the site (poor, typical or good):
- a good rating could be achieved for an additional extra cost of between 0.3% and 0.9%
- a very good rating for between 1.3% and 3.1%
- an excellent rating for between 4.2% and 6.9%
This study was done prior to the new Part L and the recent changes may affect the % figures noted.
How green do you want to be?
When considering this, an initial starting point will be to establish what statutory or other requirements, (Planning, Building Regulations and funding), are mandatory. For example:
- is on-site renewable energy required for planning now or at a later date?
- is an EcoHomes very good or other standard required?
- what improvements are needed as a consequence of new Part L regulations?
The most cost effective ways of achieving these will vary between projects and will need to consider life as well as capital costs. It is also useful to consider the best options to reduce building and estates environmental impact in the most cost effective way.
Initially, decisions can fall into three main groups:
- Quick wins - sustainable actions that have negligible, no, or reduced capital costs, eg: building orientation, off-site prefabrication, use of locally produced materials, recycling of site waste and use of timber certified as being responsibly sourced
- Sustainable actions that require increased capital costs but which can have a reasonable payback , eg: increasing insulation values, low wattage light fittings, specifying dual 6/4 litre flush toilets, aerated taps and 9/12 l/min showers and installing a low NOx boiler
- Sustainable actions that require increased capital costs but may not have a reasonable payback , eg: the use of wool insulation, solar panels, photovoltaics, micro wind generation and providing rainwater recycling
Some of the items covered by groups 1 and 2 may already be required, but it is worth considering what life-cost and commercial benefits would be gained from additional improvements and what payback is required. If you want to go the extra mile, group 3 items could be considered, but these should not generally be done unless the group 1 and 2 items have been addressed. In some cases, group 3 items will be necessary to comply with an on-site renewable energy generation requirement. Some group 3 item may be moved into group 2 by obtaining grants. In addition, some may want to use group 3 items to help give a perception of a green agenda, to help stimulate the market, or for educational reasons.
Grants
In April 2006 a Low Carbon Buildings Programme (LCBP) was set up by the DTI which can provide grants for various technologies to be incorporated into buildings. The LCBP aims to produce a more holistic approach to reducing carbon emissions and requires that energy efficient measures must also be taken. The grants are awarded on a competitive basis. Information is available online.
Case studies
A wide range case studies are available online from websites such as www.est.org.uk, www.bre.co.uk, www.greenstreet.org.uk and www.sustainablehomes.co.uk.
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