Thermal performances of sunspaces in Italy

A sunspace is a passive solar system able to contribute to energy saving in adjoining airconditioned rooms. In this paper, the thermal performances of an attached sunspace are evaluated by using two coefficients that separate the optical phenomenon of solar radiation absorption from the successive phenomenon of convective exchange with the indoor air: the effective absorption coefficient of the cavity α quantifies the solar radiation collection capacity, and the coefficient of utilization η that evaluates the contribution of the absorbed solar energy at heating of the sunspace air. The field of variability of these coefficients is determined for three different localities in Italy by a parametric analysis which points out their dependence on latitude, orientation of the glazed surfaces, optical properties of the glazed systems, the absorption coefficient and the thermal capacity of the opaque walls, rate of ventilation and on the shading.