The application of classical building-energy simulation programs is not appropriate for glazed spaces because of their particularities (as the transmission of solar radiation through windows as well as reflection and absorption). Consequently, modifications must be performed in order to correctly describe the thermal behavior of the sunspace and its (possible) coupling with the attached construction. This study presents the integration of a veranda model within the Clim2000 software designed for dynamic building energy modeling. We first introduce the model main hypotheses with focus on a simplified approach concerning the sun patch location. The proposed method is compared to an exact technique of sun patch representation. The results issued from the confrontation show that the simplified method has an excellent precision. Moreover, the complete sunspace numerical model was tested by means of full-scale experimental building. A detailed description of the experimental set-up is given, emphasizing the sky temperature acquisition and the air temperature measurement inside the experimental sunspace. Three veranda configurations were carried out: simple veranda, veranda with shutters and veranda with horizontal mask on the roof. The numerical results achieved were satisfactory comparing to experimental data. Nevertheless, additional systematically work (using sensitivity analysis) must be performed to investigate the inputs impact (particularly the sky temperature) on model predictions. (C) 2004 Elsevier B.V. All rights reserved.