Review of international regulations governing the thermal insulation requirements of residential buildings and the harmonization of envelope energy loss

There is currently a lack of harmonization in the building energy efficiency requirements that are mandated by different countries. Energy efficiency is defined by the energy yield of the facilities and by the envelope energy losses. These energy losses are mainly conditioned by the thermal envelope transmittance, the compactness factor, and the indoor temperature. This paper compares the requirements imposed on these three energy factors in residential buildings by various countries of the European Union (Germany, France, the UK, and Spain) and the United States of America. The paper also discusses the causes of the divergences in the requirements and their degrees of disparity. The paper further compares the requirements of the Passivhaus construction standard, which is highlighted by the European Union as an example of residential buildings with virtually zero energy consumption (nearly zero-energy buildings), similarly to the buildings that European countries will be forced to build by 2020. Within the current regulations, the thermal transmittance is the only factor that is used to compare the thermal insulation of buildings. However, this paper demonstrates that the thermal transmittance is not a valid parameter for the comparison and harmonization of the envelope energy losses because countries set different transmittance values for each climate zone, which are defined on the basis of different ranges of degree-day variation and are calculated using different base temperatures. Furthermore, this paper proposes a new methodology that can be used to regulate the thermal insulation of buildings to ultimately harmonize the envelope energy losses across all countries.