The building sector is responsible for 40% of the energy consumption and 36% of the CO2 emissions in the European Union. The present work investigates how the energy consumption, CO2 emissions and related costs are affected by different measures which can be adopted to satisfy the energy demand in EU single-family houses. To achieve this objective, several types of single-family houses and energy systems are analyzed in three climatic areas. The results show that a high insulation of the house envelope and the implementation of energy systems, which produce heat and electricity from renewable energy sources, are key measures to reduce the energy dependence and CO2 emissions in single-family houses. For heating and cooling systems, the energy systems based on ground coupled heat pumps had the lowest energy consumption but the systems based on district heating and biomass heaters had lower CO2 emissions. An inverse relationship between investment and operational cost is observed. The equipments with higher efficiency and lower CO2 emission have the highest and the lowest investment and operational costs respectively. (C) 2012 Elsevier B.V. All rights reserved.