Abstract The development of studies of the applications of solar energy suggests that it would be interesting to use passive solar components in the building industry. During the studies carried out as part of the Finalized Energy Project at the Building Technology Institute of the National Council of Research, a method has been developed for analysing the energy performance of passive solar components in the building industry by using test cells that simulate a conventional living environment. In this paper the authors compare the experimentally analysed performance of two passive components: an attached sunspace and a window. The paper describes the components tested, the experimental analyses of energy performance carried out, the complementary analyses performed and the results obtained. Finally the results are discussed, with an analysis of both the explanations of the results and of recommended modifications and improvements to be made to the systems in question.