In housing, the challenge for Part L1A will be to move progressively towards zero carbon and, without shock or delay, to improve design, methods and materials. Rob Pannell (pictured below) Head of Housebuilding at the Zero Carbon Hub explains
 There has been concern about the possibility of renewable energy systems, such as biomass, heat pumps or community systems saving so much carbon that fabric efficiency measures are able to be ignored. This would go against the philosophy of the widely accepted energy efficiency hierarchy which has its basis in utilising limited resources most efficiently. Here, energy efficiency measures are taken before attempting to supply the remaining energy requirements from low carbon sources. The fact that energy efficiency measures are to be a first step is generally welcomed by housebuilders.
At the time of writing, the details of the new Part L1A are still to be released and detailed comment must wait until then. However SAP 2009 has been finalised so we now know the rules for calculation of the carbon emissions. SAP 2009 will deliver a more accurate assessment of the contribution of low and zero carbon technologies as well as better predict the potential in summer of overheating. The 2009 version has been amended to report the new Fabric Energy Efficiency Standard of a dwelling using the measurement of kilowatt hours per square metre per year (kWh/m2/year) for space heating and cooling demand. This is a new ‘metric’ that may not yet be familiar to Building Control Officers. The Fabric Energy Efficiency Standard is not a requirement yet, but the reporting of it will alert builders to the new metric before they are to be required to conform. At the moment it is expected to be adopted in full in 2016 and in part in 2013. Improvements in CO2 emissions are to be measured from a fairly familiar baseline (the notional dwelling). The recent release of SAP 2009 has introduced new carbon emission factors which are not too different from the SAP 2005 ones. It has introduced party wall U values to reflect the reality of heat loss via party walls with cavities, and a thermal mass parameter, both were not included previously. Although there has been much discussion about the definition of Zero Carbon, the fundamental targets have not changed: the proposed improvements on the CO2 emissions, compared with a Part L 2006 dwelling, are broadly the same. A 25% improvement is now in place from April of this year, 44% improvement from 2013 and zero carbon (about 150-200%) in 2016. Evaluating the first stage of the energy strategy, fabric efficiency, is very much within the traditional expertise of Building Control Officers but achieving the targets on site, especially for the small builder, will be challenging. While the focus of Part L has been on fabric, services and heating systems until now, future regulations will need to address carbon performance. The transition to a more inherently energy efficient integrated design process driven by Part L and demonstrated by SAP will be a challenge, especially for the smaller housebuilder. To help the whole industry, but particularly the small builder with limited professional advice, The last Government recognised the need for design guidance to accompany the new Fabric Energy Efficiency Standard. This could take the form of model specifications and standard details that would as a minimum get everybody in the right ‘ball-park’.  The Zero Carbon Hub has also been charged with engaging with house builders, Local Authority planners, the supply chain and trade associations, who will all be key in helping to explain, promote and enable these changes. Information can be found at www.zerocarbonhub.org |
