Solar contribution evaluation for building attached sunspace in the Mediterranean climate

A glazed space adjacent to an air-conditioned room is an innovative architectural solution to use the energy contribution of solar radiation in the winter and in the intermediate months, whereas in the summer adequate shading systems are needed. The sunspace is separated from the said room by a wall, generally in part opaque in part glazed, which acts as a collection system and directly removes the solar energy to the internal room through the glazed surface, and indirectly through the opaque surfaces. Some models are available in literature for the evaluations of the solar gain for some types of sunspace-building with performance evaluations relative to Northern European climatic conditions and to the heating season (Wall, 1995). This paper, with reference to the most simple geometry made up of a glazed box fronting on a room, reports the solar contribution for a locality in the Mediterranean area. A parametric analysis has been developed that points out the dependence of the solar contribution on the glass surfaces composing the box, on the glass surface-opaque surface ratio of the intercepting wall, glass type, optical properties of the opaque surfaces and on the orientation. For some geometries the monthly variability of the solar contributions has also been pointed out. The evaluations were carried out with the dynamic simulation program DEROB-LTH, which models the optical and thermal behaviour of the glass surfaces with great accuracy, evaluating the angular aspects of the incident solar radiation and the radiative field of the solar and infrared band (Arumi-No, 1979). The aim is to verify, for the Mediterranean climate, the collecting capacity of this collection system in comparison with an ordinary opaque wall provided with windows.