Buildings are one of the most significant energy consumers and carbon emitters. As a result, their energy efficiency is a focal subject of European legislation, including the regulation of nearly zero energy building (NZEB) constructions. NZEB definition, however, differs significantly when it comes to the national level. Consequently, residential NZEBs can be characterised with altering building physical characteristics and various energy demands, according to the location of the buildings. More than that, not only the construction, but also heating, ventilation and air conditioning (HVAC) systems can be highly dependent on the geographic, especially weather conditions. With the help of dynamic building energy performance simulation (BEPS), this study reveals how the location of a single-family house affects the operational energy consumption of heating and cooling, once from the perspective of the different national NZEB regulations and also as a result of diverse climatic conditions influencing the performance of the technical building system. For the latter, we focus on one of the most expanding heat supply solution, the air-source heat pumps. To adequately address the reduction of the environmental impacts of the building sector, besides energy consumption the study analyses operational carbon emissions as well. Results highlight that though there are differences in the requirements of the specific NZEBs, some remain to produce similar indicators in all aspects, while other Member States (MS) are appealing from certain indicators, yet much worse in carbon emission. Conclusions of the paper can be considered to improve operational energy or emission management through the legislation of the building stock, MS specifically., CLIMA 2022 conference, 2022: CLIMA 2022 The 14th REHVA HVAC World Congress