There has been a growing realisation that homes designed to meet current and future standards of energy performance may fall short of expectations. The gap between what is intended and what is achieved by fabric and services can be large, with some studies indicating, for example, that fabric heat loss can be 100% more than that predicted by design. The widespread presence of such a gap would have major repercussions and introduce significant supply-side risks. For the Government it would mean that even new housing (and by inference other new buildings) cannot be relied upon to play its expected, vital role in the national carbon reduction plan. For owners and occupants, energy bills will be higher than expected, undermining buyer confidence in new (low carbon) homes. For planners, designers, product manufacturers and house builders the fallout from underperforming new homes could be damaging to reputation and business. For all, therefore, there is a pressing need to understand the reasons for the performance gap and to put in place the mechanisms and the support to address it.
The Government has taken a close interest in this issue and at Ecobuild this March, Communities and Local Government Minister Don Foster MP announced that DCLG is providing significant funding for a major work programme on the performance gap. This work, led by the Zero Carbon Hub, will follow on from a Hub-led study Carbon compliance - setting an appropriate limit for zero carbon new homes which proposed that carbon performance needed to be based on what could be achieved in practice rather than solely on theoretical design calculations.
The overall objective of this programme of work is to steadily close the performance gap over time and from 2020 to be able to demonstrate that at least 90% of all new homes meet, or perform better than, the designed energy/carbon performance.
The Performance Challenge Leaflet
Low and zero carbon homes: understanding the performance challenge (NF41)