On-site reductions in emissions – or carbon compliance – form part of the government’s plan for achieving zero carbon homes. The other part comprises off-site “allowable solutions.”
The recommendations advise on how to make the next steps in achieving zero carbon as effective as possible while also being compatible with delivery of the full range of housing required.
Separate compliance limits are recommended for detached houses, other houses and low rise apartments. The proposal to tighten the carbon compliance standard from 2016 by 70% (equivalent to 6 kg CO2 (eq) /m2/year), may not be achievable in all cases, the task group said.
The Zero Carbon Hub Task Group on Carbon Compliance for Tomorrow’s New Homes found that setting carbon compliance standards as a percentage improvement over a previous standard is "increasingly difficult to understand and at risk of causing perverse outcomes". The report therefore refers to carbon compliance in terms of an absolute limit on the predicted emissions of carbon dioxide (or equivalents in other greenhouse gases) per square metre of internal floor space.
The recommendations are that the “built performance” emissions from new homes should not exceed:
- 10 kg CO2 (eq) /m2/year for detached houses
- 11 kg CO2 (eq) /m2/year for other houses
- 14 kg CO2 (eq) /m2/year for low rise apartment blocks.
The Carbon Compliance Standards apply to built performance where as the 2006 Regulations relate to designed performance. For this reason the recommendations cannot be directly compared with the current standards. A key element of the group’s recommendations is to ensure that this potential gap is closed.
The recommendations are based on detailed modelling of technical feasibilities. They take account of cost and also reflect a wide range of other factors.
The task group also recommends an option for carbon compliance to be assessed across the whole of a development site, instead of the individual dwellings on the site.
In its report the task group notes areas for further work to be addressed in its final report, due early in the New Year. These include carbon compliance for high rise apartments, sensitivity to the price of allowable solutions, whether regional weather should be reflected in carbon compliance, and the implications for localism.
Task group members come from 25 groups in the housebuilding and building supply industries, the professions, consumer and environmental groups, and a range of others. The report and its recommendations represent a consensus, rather than unanimous, view.
The group was convened by the Zero Carbon Hub in response to an invitation by the minister for housing and local government in August 2010 to consider appropriate carbon compliance levels from 2016.
Home Builders Federation external affairs director John Slaughter said: "The Hub has undertaken a difficult and complex task very thoroughly - involving all the key parties in assembling the evidence base for its recommendations on performance standards. These will be challenging for the industry to implement, but we are confident that the Hub's ability to work through tough issues will provide a basis for the industry to resolve any concerns it may discover."
Zero Carbon Hub director David Adams, who chaired the task group, said: “It is critical that the industry has a workable definition for zero carbon homes as soon as possible and this proposal to the minister is an important step forward. I am very pleased with how well the task group worked, there is genuine desire to get this right.”
The interim task group report is available to download from the Zero Carbon Hub website www.zerocarbonhub.org.