The New (and Improved?) Building Regulations

Every three or four years we get a new set of Building Regulations. This time the proposed changes have been lauded as the first substantive legislative step on the road to zero-carbon homes. They are currently going through a ‘consultation’ phase, which means Government representatives trawl around the country explaining the proposed changes to groups of architects, builders, designers and the like.

In the last week of August 2009, in a series of briefings presented by BRE, Carbon Trust and Zero Carbon Hub, the Government reaffirmed its commitment to all new homes being zero carbon from 2016. It stated that these changes to the Regulations were the route to achieving that. It has to be said that the focus of the new Regulations, which will come into force October 2010, is entirely on reducing carbon emissions, but the method the Government is adopting to achieve this is perhaps unexpected.

The anticipation was that insulation levels would be stepped up, and U-values, air leakage and construction detail would all be changed. But far from it. All those factors, with the exception of construction detail, remain just the same. The elemental Uvalues for floor, walls, roof, windows and doors, and air leakage are all exactly the same as they were in the 2006 Building Regulations. But they are now termed ‘backstop’ figures. That is, figures below which you must not fall. The reality is that if you design to those backstop figures you will not pass the new ‘SAP 2010’ calculation — and without that you don’t get Building Regulations approval.

The changes that have been wrought are more subtle, more tricky than simple things like U-values. The whole document is now a lot more technical than it was. It has always been a difficult document but its removal from access by the common herd is now complete. Experts are now needed to interpret and implement.

More information is required at the design stage; principally this amounts to a SAP calculation that gives a ‘Pass’ (currently you need a SAP score of around 60 out of 100 to pass). To achieve a Pass the SAP must show a minimum 25% improvement of Target Emission Rate (TER) over a notional 2006 standard Dwelling Emission Rate (DER) — more of this later. Until now, submitting a SAP calculation anytime prior to completion of the building was acceptable. Now an acceptable SAP must be submitted prior to Building Regulations approval being granted and work commencing. What this means is that rather than CO2 emissions being a consequence of design, they now become the principle design criterion.

Building Control officers are being given more powers to test and enforce, in an attempt to ensure that buildings are built, and perform, as specified — the zero-carbon target means above all things that the building must perform as specified.

Which is why the focus in the Building Regulations has shifted to the TER. It relates directly to CO2 emissions. The requirement is that the building achieves a 25% reduction on CO2 emissions compared to the 2006 Regulations. There will be a new set of Regulations in 2013 and these will have a flat rate of emissions rather than a percentage reduction. Insulation, air leakage rates, installed appliances, heating fuel — these all influence the SAP calculation and are used to establish the TER but only so far as their CO2 impact is concerned.

What these proposed Regulations do is force us to design a house that performs to a given level of energy efficiency and given rates of CO2 emission, and then build the house as it is designed. It will mean designing the house, doing the SAP calculation (at a cost), changing the design in light of the result, doing the SAP calculation again — and so on until we get it right. Maybe when we get to 2016 and zero-carbon homes, the Government will leave the Building Regulations alone as there is nowhere else to go.

Further reading:

• The Code for Sustainable Homes: How to Get the Points
• The Path to Zero Carbon
• The A to Z of Green Homes