Ambition Levels of Nearly Zero Energy Buildings (nZEB) Definitions: An Approach for Cross-Country Comparison

Abstract

Since buildings account for 40% of total energy consumption and 36% of CO2 emissions in the European Union (EU), the directive 2010/31/EU “Energy Performance of Buildings Directive (EPDB)” among other legal provisions concerning the reduction of energy consumption of buildings has been enforced. According to this legislation, all new buildings must be nearly zero energy buildings “nZEB” by 31 December 2020 (public buildings by 31 December 2018). Nonetheless, the assessment of the “high energy performance” of a building is ambiguous and a cross country comparison seems to be intricate since different national building codes and nZEB definitions employ different energy indicators and methods. This paper delves into the question of how do the ambition levels of “nZEB” definitions and the transposition of the Directive 2010/31/EU into national law differ in four selected EU Countries: Austria, Germany, Spain, and England (as part of UK). The energy performance of some exemplary buildings is assessed by means of a simplified MATLAB model that is based on the norm DIN V-18599. The results drawn from this work show how diverse are building codes scopes and national “nZEB” definitions. Only 9 of the 36 studied cases of residential buildings obtain consistently the “nZEB” compliance status in all four selected countries. The results show that climate conditions, energy requirements, primary energy factors, ambition levels, and calculation methodologies lead to the problem of an uneven cross-country comparison. Moreover, primary energy consumption [kWh/m2a] set as the main quantitative energy indicator by the directive 2010/31/EU might not be the most suitable one for an EU level comparison.