To evaluate the energy of the building adaptation is necessary to compare actual consumption for heating with expected values. It is always necessary to carry out the actual conversion (invoiced), energy consumption based on actual weather conditions. However, these are generally reduced to an average daily temperature of heating and the number of days and usually it is assumed that the solar radiation is uniform in each year. This simplification was less important buildings with small thickness thermal insulation and a minimum percentage contribution of solar heat gains. Nowadays, when most of the buildings is insulated or built with high-quality thermal insulation of the situation is different and fluctuations in solar gains can be significant in the energy balance.