Double skin facades (DSF) are gaining popularity for their ability to reduce solar heat gain in buildings. However, research works on the impact of DSF on the energy management, aerophysics and air conditioning of buildings are still at their infancy. The concept of envelope thermal transfer value (ETTV) has been specifically applied to evaluate the solar radiation gain component through a DSF fenestration system. The aim of this paper is to study the effects of DSF on the solar heat gain, the ETTV and hence the energy management within buildings. A systematic methodology to investigate the effectiveness of DSF in reducing solar heat gain has been presented. Experimental works have been performed to obtain the solar heat gain coefficient (SHGC) values of a DSF fenestration system. These values are then applied to compare the ETTVs generated from a model building with different DSF configurations, namely, different wall-to-window ratios and varying shading coefficients. (C) 2009 Elsevier Ltd. All rights reserved.