July 7, 2009

The Code for Sustainable Homes (CSH) – What is it, and what does it mean for housebuilders and homeowners?

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What is it?

Developed by the Building Research Establishment (BRE), the Code for Sustainable Homes (CSH) was introduced in response to the need for a consistent national standard for the assessment of new homes with regards to sustainability. Although many argue that the introduction of the scheme is overshadowed by the need for significant improvement of the existing housing stock, the government believes that tackling the performance of new dwellings is key to kick-starting the long haul towards sustainable construction as a whole, and the formulation of best practice for the future.

The CSH covers 9 broad categories, aiming to encompass the overall objectives of sustainable development:


1. Energy and CO2

2. Water

3. Materials

4. Surface Water Run-off

5. Waste

6. Pollution

7. Health & Wellbeing

8. Management

9. Ecology

Projects are rated from 1-6 (with 6 being the highest) depending on their compliance against these criteria with a number of credits available within each category. Each code level requires satisfaction of a number of essential elements (including water and energy requirements which must be satisfied at all levels of the code), although the remaining credits may be achieved through any combination of the remaining “tradable” elements. The selection of which categories to aim for will usually depend on the experience of the design team, project constraints and, more often, cost.

Of course, not all categories carry equal importance and are therefore weighted to reflect this with the total credits achieved in each category being converted to points based on the weighted percentage contribution of the corresponding category. In fact, considerable emphasis is placed on energy use, in line with the principle objectives of the CSH in achieving carbon reduction targets.

Although, on the face of it, the system may appear complex, the use of essential and tradable elements ensures the basic principles of sustainable housing are achieved whilst giving the code significant flexibility in the way ratings are achieved.

The CSH is a two-stage assessment requiring demonstration of compliance at both design and post-construction stages. An interim certificate is awarded during the design phase of assessed projects based on evidence of its compliance with each category (depending on code level and tradable elements). Following completion a mandatory post-construction review is conducted to ensure design intent is carried through to the completed building. Following successful demonstration of this, a final certificate is then issued.

The majority of current CSH projects have in mind a specific code level from the outset although the true extent and impact of achieving this may not always be obvious until considerable design work has taken place. It is therefore advised that the code assessor be appointed at the earliest possible stage to utilize guidance on achieving the maximum from the project as well as managing the compliance process.

Who has to comply?

After a year in use and following targeted feedback, the government declared ratings against the CSH would become a mandatory requirement for all new homes as of April 2008.

But what does this really mean? Well, although assessment itself is not yet mandatory, a rating against the scheme (in the form of a certificate) must now be included within all Home Information Pack’s (HIP) associated with the sale of new homes (in addition to existing Energy Performance Certificates). However, those who choose to opt out of an assessment can simply apply for a zero rated certificate to communicate this.

Although this essentially means that compliance with the CSH is not yet truly mandatory for the average new build, it should be noted that within the realms of social housing, funding for such projects is directly associated with minimum levels of compliance (generally level 4 at present). As a result, the majority of current examples of code compliant housing can be found within this sector.

Going forward though, things are set to become much tougher for all designers and builders as milestone compliance levels are introduced periodically, moving towards the requirement for all projects to achieve level 6 compliant, zero carbon standards by 2016, just 7 years from now! In addition, as the use of the CSH develops, key aspects of the code will be encapsulated as mandatory requirements within new revision of the building regulations.

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