Nonconformities, Deviation and Improvements in the Quality Control of Energy Performance Certificates in the Basque Country

The energy performance certificate (EPC) is the core source for the European Union (EU) to obtain information about the efficiency levels of building stock and plan energy target paths. For this reason, and due to its wide variety of applications, it is important to ensure its quality. This study evaluates the quality of a representative EPC sample taken between 2014 and 2019 following the control methodology established in the Basque Country. The results show that inaccuracies exist: 78.1% of the sample presents at least one inconsistency, and the root mean square of relative error for non-renewable primary energy consumption (nrPEC) and CO2 emissions is 20.3% and 22.0% respectively. Another finding of this investigation is the upward evolution of errors. Finally, estimates show that any EPC in the Basque Country can have a relative error in the range of +/- 39.98% for nrPEC or +/- 43.23% for CO2 emissions with a probability of 95%, and the same error distribution in positive or negative direction. This suggests that at least half of EPCs were not the result of deliberate wrongdoing but may have been due to a conservative attitude or misconceptions on the part of the certifier.

Automated summary

This study evaluates the quality of a representative EPC sample taken between 2014 and 2019, revealing inconsistencies in 78.1% of the sample and an upward trend in errors. The results show an average relative error of around 20% for non-renewable primary energy consumption and CO2 emissions. It is suggested that at least half of the errors in EPCs may be attributed to certifiers' conservative attitudes or misconceptions.