This paper illustrates an energy upgrading proposal of a historical building in Naples (Italy): Palazzo Fuga, better known as the Real Albergo dei Poveri which was built in the second half of the XVIII century. The proposal consists of energy efficiency interventions on the building envelope and its plants. As energetic and thermal aspects are concerned, simulations were performed in order to size a photovoltaic system, considering lighting aspects, and to evaluate the improvement of the building energy performance. Furthermore, thermal and lighting measurements were performed with a double aim: to verify the factual state of the building and to calibrate the calculation tools to the particular situation. In this paper obtained results concerning the feasibility of interventions will be presented and discussed. (C) 2014 Elsevier B.V. All rights reserved.