Implementation of Active Transparent Facades (ATF) in buildings has been an object of broad application in recent years, both in new or existing buildings. However, there is little experience in the predicting the operating behavior of an ATF. Sometimes the results obtained are not satisfactory and an extra energetic cost is necessary to obtain suitable comfort conditions in the inner space of the building, especially in Mediterranean climates, where large solar gains are a constant condition along throughout the year, and such large semi-transparent areas can produce significant over-heating in buildings. Computational Fluid Dynamics (CFD) has proven to be a useful tool for modeling flow and heat transfer in ATF including conduction, convection and radiation heat transfer phenomena. The aim of this work was to evaluate, by means of CFD, the influence of several construction and operation parameters of the ATF (such as optical properties of the materials, geometrical relations of the facade or flow stream conditions) in terms of energy savings, measured as a reduction of the solar load entering the building. Conclusions on the thermal behavior under several configurations of ATF were obtained. It was found that the parameters that affect the most the reduction on solar load gain are related with the optical properties of the glass. It was also seen that an increase of the length-to-depth ratio causes a decrease on the ATF efficiency in terms of solar load gains. For the tested cases, an increase on the turbulence intensity does not lead to improvements in the reduction of solar load gains. Although an increase on flow velocity necessarily means an increase on the turbulence mixing levels within the flow stream, the added mass effects due to the increase on flow velocity are more significant than the turbulence mixing effects over heat fluxes through the ATF. (C) 2008 Elsevier B.V. All rights reserved.