The focus of the Energy Performance of Buildings Directive (EPBD) was on standardising the assessment and energy efficiency rating of Europe's building stock. Energy assessments and energy performance certification (EPC) concentrated on the material properties of buildings, and used simple physical models to estimate energy consumption from these inputs. However, the EPBD has always allowed the use of empirical energy consumption to assess buildings. This paper comprises an analysis of energy assessments in the six largest European countries, looking at the methods used to generate EPCs and how they vary across countries, regions and buildings. Differences are noticeable and can have considerable impact on what constitutes an energy efficient building within a standardised assessment framework. For example, Germany, Poland and France currently use absolute energy consumption as the basis for EPCs for some of their building stock. Each country applies different philosophies, categories and values to the assessment of the material and physical properties of its building stock. The simultaneous use of empirical and modelled energy assessments for existing buildings can generate varying results with implications for energy policies that expect standardised assessments. This research quantifies the current extent and use of empirical and modelled assessments and further examines the use of estimated values within modelled assessments. Our research reveals the extent to which empirical data is currently being used across Europe and the variation in input data used for the physical modelling of energy consumption in buildings. The use of empirical energy assessments can be consistent with the EPBD and formalising their use may be a way ahead for a more coherent low-energy building policy. Variations in the input values available for modelled energy assessments can diminish the authority of assessments for both building residents and policymakers. Identifying good and bad practice in energy assessment may help to develop better compliance structures for the future. This research makes clear the value of carrying out a pan-European analysis of energy assessment methods.