Building performance evaluation and certification in the UK: Is SAP fit for purpose?

Improving the efficiency and performance of the UK residential sector is now necessary for meeting future energy and climate change targets. Building performance evaluation and certification (BPEC) tools are vital for estimating and recommending cost effective improvements to building energy efficiency and lowering overall emissions. In the UK, building performance is estimated using the standard assessment procedure (SAP) for new dwellings and Reduced SAP (RdSAP) for existing dwellings. Using a systems based approach we show there are many opportunities for improving the effectiveness of BPEC tools. In particular, if the building stock is going to meet future energy and climate change targets the system driving building energy efficiency will need to become more efficient. In order to achieve this goal, building performance standards across Europe are compared highlighting the most effective strategies where they are found. It is shown that the large variance between estimated and actual energy performance from dwellings in the UK may be preventing the adoption of bottom-up energy efficiency measures. We show that despite popular belief, SAP and RdSAP do not estimate building energy efficiency but instead attempt to estimate the cost-effective performance of a building and thus create perverse incentives that may lead to additional CO2 emissions. In this regard, the SAP standard confounds cost-effectiveness, energy efficiency and environmental performance giving an inadequate estimate of all three policy objectives. Important contributions for improving measurement, analysis, synthesis and certification of building performance characteristics are offered.