Power signature method for energy performance certification of single-family houses

Peer-reviewed paper 7-212-26

Only about 20% of Sweden’s single-family houses have a valid energy certificate. In the case of energy renovation under the Taxonomy Regulation (down to the top 15% or 30% reduction), banks require verification via independent metering, which means two certificates – before and after measures – and high costs that hinder energy efficiency. At the same time, today’s billing meters provide hourly energy data.

The study examines whether energy certificates can be simplified by using hourly data from the energy companies and the power signature method. The goal is an automatic calculation model that calculates heating energy without the need of a site inspection. The study includes simulations and analysis of electricity and district heating data from eleven single-family houses. The results show that power signature, together with balance outdoor temperature and degree days, can distinguish heating from other energy.

The method was compared with energy certification according to current method. Since the slope of the power signature is used in the new method, there is no need for guessing standard values for hot water and domestic electricity, which improve quality by providing a more transparent and systematic calculation.

The method has the potential to be automated and reduce costs, although an initial site inspection still is required. In the case of a repeated certification, the process could in principle take place electronically in a few minutes, regardless of which independent expert is carrying out the certification.