Quantitative analysis of the divergence in energy losses allowed through building envelopes

There is currently a lack of international harmonization on the insulation requirements for the buildings. Given that this parameter defines the maximum energy losses allowed through a thermal envelope, building energy consumptions can vary considerably between countries. Both the United States of America (US) and the European Union (EU) should address this problem by unifying the energy design criteria of their buildings. The EU requires that all new buildings constructed starting in 2020 must be nearly zero-energy buildings (nZEB), as defined in the Directive on Energy Efficiency in Buildings of 2010. To evaluate the extent of this lack of harmonization, in this paper are calculated the maximum energy losses through the thermal envelope of a typical dwelling when applying various international regulations (such as the US regulations and those established by Germany, France, England and Wales, and Spain). The results are compared with those obtained when applying the requirements of the Passivhaus standard (taken as a reference for nZEB in the EU). It will be verified that there are major differences in the energy losses allowed through building envelopes among these countries and among the different climate zones defined in each country. Moreover, the challenges set by these countries related to energy consumption and CO2 emissions are also reviewed. The disparity between the objectives proposed by these countries suggested a distinct tendency towards increasing current differences in their standards. (C) 2015 Elsevier Ltd. All rights reserved.