In the last few years, more and more attention has been focused on energy issues, as it is pointed out, for example, by the Directive 2002/91/EC on the Energy Performance of Buildings and Directive 2009/28/EC on the promotion of the use of energy from renewable sources. However, in order to do that, reliable tools for technicians to design systems for such topics should be provided. Nowadays, several software are available; the weak point is the availability of reliable climatic data and, above all, the ones referring to solar radiation. In this work, after a short overview of the world climatic databases, a description of three statistical methods for the elaboration of a climatic reduced set of data is reported. Then, referring to the climatic station of Palermo, Italy, we build three different sets of data utilizing the three statistical methods and compare these sets of data by means of two applications, namely the energy consumption of a simple building and the energy produced by a photovoltaic (PV) system. (C) 2012 Elsevier Ltd. All rights reserved.