Abstract This paper examines the methods and input data used to assess the energy performance of residential buildings. The work concentrates on the assessment methods used to generate Energy Performance Certificates, under the European Energy Performance in Buildings Directive, for existing residential properties in the six largest European countries: UK, France, Germany, Spain, Italy and Poland. Buildings are associated with 40% of final energy consumption across the European Union however this paper reveals significant variation in the methods used to identify and assess this energy consumption. The research indicates that best-practice sharing between different countries governed by the same framework is not always evident and, by taking different approaches, each country is likely to draw different conclusions about their building stock, and how to market transform these dwellings in the future.