Buildings consume in Spain to 26.1% of final energy, corresponding to 17.5% of the domestic sector and 8.6% of the service sector. These data make us reflect on the energy savings that could be carried out by taking efficient measures in the enclosures of buildings, on the one hand, and systems that provide the energy needed to obtain comfort conditions. Thus the current legislation displays a large number of regulations on the matter: Technical Building Code, Regulation of Thermal Installations in Buildings, etc. The Basic Procedure for Certification of Energy Efficiency in Buildings has came into force recently, making it compulsory to qualify new buildings and / or old that are sold or leased, either as a whole or individually. The energy qualification is obtained as a result of quantifying the demand and the final energy consumption in a building. In this study we perform a series of simulations, using the software CERMA with a typical domestic building, placing it in different climatic zones of the Spanish territory, analyzing the obtained results. The most significant results have been the similarity in energy the energy label certification obtained in all scenarios and the lack of harmony between energy rating scale and energy consumption. The ultimate goal is not only the energy qualification of the building but also to know how we can get an improvement on it. It must be stressed that the study was conducted before the entry into force of the Order FOM/1635/2013 from September 10th 2013, laying updated the Basic Document DB-HE.