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Lessons from the field – CSH in action #1

by Mel Starrs on February 20, 2012

in Code for Sustainable Homes

I was recently approached by a long time friend of the blog to see if I could host a guest post, about lessons learned whilst dealing with Code for Sustainable Homes. I said ‘certainly!’. We are not able to mention the project – it will remain anonymous. The author was the sustainability manager for the contractor and developer, and worked with the code assessor to ensure they provided the evidence and tracking progress towards the certification. The code requirement was a condition of funding, as well as a planning requirement and developer objective. This is the first of a short series of posts:

Here is a situation that occurred on a recent project that was being assessed for the Code for Sustainable Homes, which goes to show how easy it is to get things wrong.

Can you spot what might be wrong with the picture?

This insulation was supplied and installed on site. The supplier sells two types of insulation, both with very similar names, one ending with an “A” and one with an “X”.

The letter signifies the type of gas used as a blowing agent. In all other respects, the insulation has the same thermal properties. The “A” type has a low Global Warming Potential (GWP) of <5 which is compliant with credit POL1 of the Code for Sustainable Homes, where as the “X” type uses a different gas as a blowing agent, with a much higher GWP of around 1300.

The ”X” type was used on site, despite the particular specification calling for insulation with a GWP of <5, and it was only discovered once the material had been installed and the delivery notes were being reviewed by the Code assessor.

How did this happen, you might ask! In this case the contractor had proposed an alternative material and had issued the proposal to the main contractor on their web based document control system flagged as being “for information”. In fact when downloaded, the proposal requested an approval, but this was not noticed at the time.

As the material was installed, it was not practical to remove and replace it. This meant that the project lost 1 Code for Sustainable Homes credit, equivalent to 0.71% of the total score.

Fortunately the use was isolated to one particular building on the development, so the others were not affected. The project had allowed for a small buffer of credits, which meant the required rating could be achieved despite the loss of this credit.

This prompted a review of all other specifications. We found 35 instances where these were incorrect, for example some specifications called for insulation with a GWP of better than 5. To the layman, a higher number might be perceived as “better than 5”, which would be non-compliant. One of the specifications had the incorrect symbol >5 rather than <5 which was definitely incorrect, and some were found to call for a GWP of “5 or less”. Whilst this might seem correct, “5 or less” could be easily interpreted as being a GWP of exactly 5, which is not compliant with the Code requirement for a GWP of less than 5.

Although, in this instance the loss of the credit did not impact on achieving the required Code rating as it was not a mandatory credit, and the score was made up for in other aspects of the Code, it does provide a valuable lesson on how easy it can be to get things wrong. Achieving credits in the Code for Sustainable Homes, BREEAM and similar assessments, requires attention to detail, and that all people involved understand the implications of even very small changes to specification or other details.

BREEAM and CSH are often criticised for being ‘box-ticking’ exercises, but box-ticking is occasionally a necessary evil. For more information on GWP Wikipedia has a currently transparent and easily understood explanation here.

I have at least one more post in this series – I might add some more tales of my own and of urban legend.