Do zero carbon homes make sense?

Panel: Panel 7. Innovative buildings technologies

Authors:
Les Shorrock, BRE, United Kingdom
John Henderson, BRE, United Kingdom

Abstract

The Code for Sustainable Homes (hereafter, "the Code") was launched in the UK in April 2007. The Code sets out six levels of sustainability which, in terms of carbon dioxide emissions, represent different levels of improvement relative to the requirements of the 2006 Building Regulations (Communities and Local Government, February 2008). Level 6 of the Code corresponds to a zero carbon home. The UK Government has an aim that, from 2016, all homes built should achieve this standard.

Many people question whether this ambitious timetable is actually feasible. It has been argued that it would be more sensible to focus on improving the energy efficiency of the existing housing stock rather than rushing to achieve zero carbon standards in new homes. This argument is examined by considering the cost-effectiveness of the different levels of the Code, the cost-effectiveness of energy efficiency measures that can be applied to the existing housing stock, and their respective carbon dioxide savings.

The results indicate that the energy efficiency measures that can be applied in existing homes are generally considerably more cost-effective than building new homes to different levels of the Code. On the other hand, if achieving carbon dioxide savings is of overriding importance, the results also suggest that constructing new homes to level 5 of the Code is actually more attractive, in terms of the cost per tonne of carbon dioxide saved, than constructing to levels 3 and 4. Equally, constructing to level 6 of the Code has a cost per tonne of carbon dioxide that is almost the same as that for levels 3 and 4, but it saves considerably more carbon. This argues for a rapid move towards a requirement for zero carbon homes, consistent with the Government aim.