Part L - a stepping stone to zero carbon?

The details of the changes to Part L 2013 in England have now been released, including new Approved Documents L1a and L2a for new buildings. As we already knew from previous government announcements, the changes will start to be implemented from 6 April 2014 and aim to achieve a 6% improvement over Part L 2010 for domestic buildings, and a 9% improvement for non-domestic.

Different building types will be pushed by different amounts, as the headline improvement figures are weighted across the build mix. The changes will require developers to review their current designs, but will these be significant enough to provide the learning that is needed on the journey to achieving zero carbon?

However the small percentage improvements over 2010 standards will reduce the learning opportunity for the house building industry on the road to zero carbon

The details in the Approved Document L1a show that the domestic buildings targets are achievable through fabric alone, and also introduce a new mandatory fabric energy efficiency standard – similar to the standards included in the Code for Sustainable Homes and promoted by Zero Carbon Hub, though not set in the same absolute terms and so likely to be less challenging. The Zero Carbons Hub has consistently advocated a focus on fabric as an essential basic principle of zero carbon, and it is good to see that this is being implemented and prepared for in 2013.

The domestic targets are designed to allow consistency of specification across unit types, which will help to address some of the issues I wrote about in my last article on the design-as built energy performance gap project being coordinated by the Hub. Some of the changes proposed at the consultation stage to address the gap, such as the introduction of confidence factors linked to the application of a QA process, have been put on hold and are expected to be informed by the outcomes of the performance gap project.

However, the small percentage improvements over 2010 standards will reduce the learning opportunity for the housebuilding industry on the road to zero carbon. The same picture is given in Wales, where a 25% or 40% reduction over Part L 2010 was originally proposed at consultation for domestic buildings, which has recently been reduced to 8%, though non-domestic buildings remain at 20% as originally proposed.

No changes have been made to improve the overheating checks introduced as part of the compliance checks, and this is likely to require further review in the future. We should not underestimate the potential danger posed to the health of residents through overheating, which has already been identified as an issue in some new homes, nor the risk of a future performance gap issue as residents are driven to use methods of cooling.  The Hub is currently working with government and industry to scope out a programme of work to reduce the risk of summer overheating, and I will be writing more about this project in a future article in Building.

Experience to date suggests that industry as a whole still has a lot to learn in order to achieve zero carbon in practice, and through the performance gap project and other innovative schemes many organisations are showing a promising appetite to do so. The heat is on for 2016, as the step to zero carbon is now looking quite big one and will require clear, early guidance from government as well as ambition from industry to choose to meet stronger targets, realising benefits for building owners and occupiers as well as the UK as a whole.

Rob Pannell is the managing director of the Zero Carbon Hub