Energy and Economic Savings Assessment of Energy Refurbishment Actions in Italian Residential Buildings: Comparison between Asset and Tailored Calculation

Residential buildings have become one of the leading sectors in the energy refurbishment process towards the clean energy transition. Energy Performance Certificates (EPCs), based on the asset rating calculation method, are often used to quantify the energy performance in standard conditions before and after renovation, but their energy outcomes can significantly differ from the actual energy consumption and savings. More consistent results can be obtained by adopting a tailored approach, capable of considering more the actual building operation conditions and users' behaviour. In this framework, the study evaluates the heating energy needs of Italian representative multi-family houses in all the climatic zones and five retrofitting scenarios with both asset and tailored ratings. Finally, a cost-benefit analysis, based on energy savings and interventions costs, is also carried out to assess the affordability of the refurbishment actions depending on the adopted calculation methods. The analysis of retrofitting scenarios highlighted that asset energy outcomes are generally slightly greater than the tailored ones (differences of around 3-13% on average), but the affordability of the chosen energy efficiency measures is significantly overrated. It could underline the need to adopt the tailored approach for more accurate energy savings assessment and economic evaluation.

Automated summary

Residential buildings are leading the way in energy refurbishment towards clean energy transition. Energy Performance Certificates (EPCs), based on asset rating, often provide different results from actual energy consumption and savings. A tailored approach considering actual building operation conditions and users' behavior yields more consistent results. This study evaluates heating energy needs of Italian multi-family houses in different climate zones and retrofitting scenarios using both asset and tailored ratings. A cost-benefit analysis is also conducted to assess affordability of refurbishment actions. The analysis shows that asset energy outcomes are slightly higher than tailored ones, but the affordability of energy efficiency measures is significantly overrated, emphasizing the need for a tailored approach for accurate energy savings assessment and economic evaluation.