Benchmarking Danish, Estonian and Finnish NZEB requirements with European Commission recommendations in residential and office buildings

Abstract

Comparing building energy performance across countries is challenging due to varying climatic conditions, calculation methods, primary energy (PE) factors, and input data discrepancies. This study systematically compares nearly zero-energy building (NZEB) requirements and energy calculation methodologies between Denmark, Finland, and Estonia, using a new office building, an apartment building, and a single-family house—each designed to comply with the respective national NZEB requirements. To account for climatic differences, a heating-degree-days correction factor was applied to thermal transmittance values of building envelope components. NZEB requirements of each country were then compared against the European Commission (EC) recommended values (EU 2016/1318) through normalization and benchmarking, employing detailed dynamic simulations. Both national and standardized (EN 16798–1:2019) input data was used with country-specific climate. In the benchmarking analysis, simulated primary energy performances were evaluated against EC NZEB thresholds, and the on-site renewable energy generation required to meet these targets was quantified. Results show that Estonian NZEB align with EC recommendations for Nordic climates, but EC Oceanic benchmarks were unmet even when Estonian configuration were applied to Danish climate indicating that the Oceanic benchmark is more ambitious than Nordic. Danish and Estonian national NZEB PE thresholds for office buildings showed a gap of 7% and 23%, respectively, to meet EC recommendations. However, the case study office building, surpassing Estonian NZEB standards, met both Nordic and Oceanic EC benchmarks. Finnish NZEB requirements were readily met by the case study buildings, highlighting that Finnish NZEB thresholds are currently less stringent compared to those of Denmark, Estonia, and the EC recommendations.