National methods fail to calculate standardized deep renovation concepts for dwellings: Benchmarking in three EU climates

Abstract

Renovation of existing buildings has been highlighted as an essential action in the European Green Deal and in the latest revision of the EPBD to achieve energy efficiency targets. Renovation Wave strategy aims to double the deep energy renovation rate in EU by 2030, while specifically targeting the worst-performing segment of the existing building stock. The objective of this study was to assess the energy performance of deep renovation concepts on single and multi-family houses in three different geographical settings – Germany, Italy and Estonia. Typical German 1970s buildings were used as a baseline reference, and it was shown that very similar renovation concepts can be successfully applied across Europe that provides good bases to develop standardized solutions. Energy performance of two common renovation concepts was assessed both with national calculation methodologies and dynamic simulation with harmonized inputs and detailed heat pump plant models. The renovation concepts included improved envelope insulation and airtightness, switched to heat pump systems and heat recovery ventilation as well as incorporated on-site PV while complying with nearly zero-energy requirements for major renovations in all three countries. National energy calculation methodologies showed good accuracy for before the renovation situation but failed in many cases to calculate adequately NZEB renovation concepts with heat pumps and PV, indicating the development needs towards hourly calculation and more detailed treatment of heat pumps.