Just over a year on from the introduction of a mandatory Code for Sustainable Homes rating for all new-build dwellings (which took effect from 1 May 2008), the NHBC Foundation has produced an easy to follow, step-by-step manual to help builders and developers comply.
While many housing developers, particularly larger builders and those working in the social sector, have become familiar with the code, the technical guide, which is currently nearly 300 pages long, can still present a daunting prospect. The Code Simply Explained report has been designed by experts from BRE and NHBC as a handy guide to achieving a good score in a practical and cost-effective manner, particularly focusing on levels three and four as the most commonly specified at present, but with principles equally applicable to all levels of the code.
Below are 10 top tips from the NHBC Foundation for climbing up the code rating system, adapted from The Code Simply Explained. A full copy of the report and further information about the wider resources and advice available from the Foundation can be found at www.nhbcfoundation.org
Start early
At a very early stage, before the site layout has been finalised, start to consider code-related issues. Particularly mandatory requirements which must be implemented in full to achieve any code level rating in many cases. But credits may be achieved more easily for issues such as energy, daylighting, and ecology among others if measures are integrated into the design now, for example by orientating roofs and living spaces to the south to make best use of solar energy. Seek advice from a qualified code assessor to ensure that the criteria have been correctly understood.
Target easy-win credits
Several credits can be achieved through measures which are independent of the design and achievable in all developments. This includes simple measures such as energy-efficient light fittings and a drying line, and will be cost-effective to specify in most developments.
Enhance ecology and reduce flood risk
By taking site factors such as flood risk and ecological values into account at an early stage, the baseline for the code score can be assessed. Sites of high ecological value or with a risk of flooding are likely to increase the cost of achieving a high code rating, so this needs to be considered. An ecological survey following code guidelines will still be worthwhile to improve the score for most sites, both Greenfield and previously developed.
Effective construction and supply chain management
Implementing measures relating to the construction stage such as monitoring of energy and water use and reducing pollution risk can be a cost-effective way to improve your score, but requires preparation in advance of starting on site so that procedures are in place and the workforce are aware of them. In particular, a site waste management plan is a mandatory requirement so must be given early consideration. Modern Methods of Construction using offsite construction can help make this process easier.
Reduce water consumption in the planning stages
Early attention to sustainable drainage systems (Suds) can be cost-effective and potentially provide amenity value through the use of water features such as ponds. The mandatory requirement to reduce runoff volumes, and not just peak run off rates, is an important one to get right, necessitating full consideration of infiltration and rainwater harvesting opportunities. Rainwater harvesting can contribute to reducing surface water runoff and reduce internal water use, but this needs very careful design to meet the requirements of both.
Plan the layout to give the space you need
Considering the site layout from an early stage gives the best opportunity to include space requirements for highly weighted Lifetime Homes credits, and a design that enables direct access to rear gardens means that garden sheds can be used for cycle storage. An option for a room-in-the-roof means that an extra credit can be gained to improve the score later on, if this proves to be the preferred strategy.
Consider the environmental impact of your materials
Looking at the proposed construction materials early means that most types of constructions can perform well – there are many equivalent products with lower environmental impact but equally fit for purpose. There is a mandatory requirement for ratings against the Green Guide so a strategy to achieve that is vital.
Ensure your house is Secured By Design
Incorporate the recommendations of a police architectural liaison officer or crime prevention design officer to meet Part 2 of the Secured By Design award is a straightforward way to gain extra credits
Insulate to improve performance and reduce consumption
Designing the building fabric to achieve a good sound performance and air tightness and to avoid thermal bridges requires many of the same principles and can help achieve credits in several different areas. Building fabric with a high thermal performance will help to reduce carbon emissions and provide benefits to residents for the full lifetime of the building,
Employ strategies to enhance energy sources
Ensure a strategy is in place for low and zero carbon energy technologies, such as renewables and CHP. Most developments will need these technologies to meet code level three or higher, and the mandatory requirements for carbon dioxide emissions can be very expensive or impractical to achieve unless their integration is planned from the start.
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