Resumen
Energy efficiency in the residential sector is one of the priorities of theEuropean Union. It is estimated to achieve an energy saving of 27% in thegroup of buildings in the residential sector in the EU countries by 2020through the directives issued by the European Commission. The housingstock of Spain are among the least energy efficient in Europe as a result,try to introduce governmental aid to encourage thermal refurbishmentof residential buildings. Currently programs energy rating in Spainfocus on the evaluation of annual CO2 emissions, however indicatorsannual primary energy consumption or investment cost improvementmeasures are not taken into account (Rua & López-Mesa, 2012). Thetarget is investigates the economic aspects of investment and savingsin energy efficiency improvements to houses, making a comparisonbetween alternatives and starting situations that may appear at the timeto evaluate the response of a building with order to deepen anothervalid indicator for EE actions on existing buildings (Ahern, Griffiths &O?Flaherty, 2013).