EPB versus real energy use in high-performance houses

How accurately do official energy performance calculations assess the real energy use in high-performance houses? This question was investigated in a statistical study commissioned by the Flemish Energy Agency (VEA), analysing data on 537 dwellings: their building envelope and system characteristics and calculated energy performance reported in the Energy Performance of Buildings (EPB) database, the energy use collected by the energy utilities and socio-demographic and behavioural data from surveys of the inhabitants.

The calculated energy use was strongly correlated with the real energy use, but the heating energy use of most houses was overestimated and the prediction error varied strongly between individual cases. The study showed that this results at least as much from the work of the EPB-assessors as from the behaviours of inhabitants. The often more thorough assessment of high-performance houses also artificially increases their better ratings compared to more standard houses.