Given the current energy context and environmental challenges, European countries have set their own targets to tackle climate change, security of supply and fuel scarcity. The building sector has a significant energy saving potential and the European Union has already set a framework for the Member States.Shifting towards low energy buildings and the improvement of the energy efficiency of existing buildings are of major importance. However, each country has different ways to deal with this issue, depending on its national energy policy, building regulations and standards. There is an urgent need for a common framework for low energy buildings and transparency and comparability of the calculation methods are indispensable not only for the stakeholders of the building sector but also for the general public. This study aims to understand these differences focusing on the comparison of the calculation procedures used for compliance to regulations and standards in three European countries: the Passivhaus standard (PHPP) in Germany, the SAP rating and Code for Sustainable Homes (SAP) in the UK and the Bâtiment Basse Consommation (TH-CE) in France.