Abstract
This article reports the results of pioneer research in Spain whose objectives are to analyze the level of understanding of energy performance certificates (EPC) by households and to know the willingness to pay (WTP) for energy efficient housing and the influencing factors. By means of contingent valuation, the WTP was calculated to improve the energy class of a typical apartment in Barcelona. In general, respondents were unaware of the elements that determine energy class, especially individuals with less education and senior citizens. This lead to mistrust of certificates and to the undervaluing of energy-efficient housing. The WTP for the improvement E-> A was found to be 30.58 euros/month, which equals electricity bill savings. Behind WTP there were underlying financial reasons, such as income level or economic savings, but also sensitivity to the environment and responsible consumption. Finally, those who prefer to buy rather than rent seemed to be more willing to pay for a better rating. All this constitutes a clear message for energy and housing policy.