Solar radiation for buildings and energy applications: the feasibility of the reduced data set for Mediterranean sites

In the last years several computer programs for thermal simulation of buildings have been quickly spread; they allow to describe the thermal behavior of buildings and to verify their energy efficiency, in order to suggest eventual improvements as from the design stage. Most of these simulation tools generally need a complete input data set and, in particular, information referring to the climatic conditions of the site where buildings will be built-up. As it is well known, among climatic issues, particularly important for the thermal energy balance is the solar radiation. In this paper authors present a short reference year of the solar radiation, more precisely the Monthly Average Day (MAD) for a town of the Southern Italy (Palermo). Moreover, authors have compared the climatic data of the Monthly Average Day (both for global and diffuse solar radiations) obtained from hourly measures for seven years, with those obtained both from geo-astronomical parameters and from the monthly average of the daily global solar radiation, which is commonly adopted on purposes. The comparison does suggest a particular caution in the choice of the method for generating reduced data sets of the solar radiation for these Mediterranean sites.