(i) Physical energy flow accounts (PEFA) provide information on energy flows arranged in a way fully compatible with concepts, principles, and classifications of national accounts – thus enabling integrated analyses of environmental, energy and economic issues e.g. through environmental-economic modelling. PEFA complement the traditional energy statistics, balances and derived indicators which are the main reference data source for EU energy policies. (ii) PEFA record the flows of energy (in terajoules) from the environment to the economy (natural inputs), within the economy (products), and from the economy back to the environment (residuals) (iii) EU member states, EFTA countries, EU candidate countries and potential candidates. (limited to data availability) (iv) Data are collected by means of a questionnaire