Energy Certification of existing buildings: experimental analysis and physical-mathematical modeling

Abstract

The solar gains through windows usually provide an important contribution to the summer cooling load of a building. The current definition of the gain/loss utilization factor for the evaluation of the summer thermal load derives from a curve fitting procedure based only on experimental results and not on the building thermo-physical and geometrical properties, so it often proves to be not well suited. On the basis of the Admittance method, as the reference mathematical model for the building energy assessment (implemented into a routine developed in the Mathcad environment), the present work is intended to give a theoretical contribution for the definition of a solar gain response factor (F) as a function of the intrinsic building features for the evaluation of the radiant thermal fluxes released to the internal space, through the following steps: - Set up of a reliable mathematical model for the treatment of solar gain, and comparison with Energy Plus as far as the building thermal response is concerned; - definition of a correlation for the solar gain response factor F, as a single value transfer function able to link the input (the driving force) to the output (the thermal load); - classification of the Italian building stock typologies through the solar gain response factor F.