This project focuses on the energy performance of a Double Skin Façade operating accordingly to the concept of preheating fresh air incoming into the building in cooperation with a mechanical ventilation system. The first part of this report deals with three sets of results from measurements performed in a full scale model during: November 2006, the turn of April and May 2008 and May 2008. In the last case a shading device was added in the Double Skin Façade air cavity. The experimental setup has been validated through tracer gas experiments determining the airflow. Different weather conditions have been analyzed, with special focus on solar radiation and the effect of solar shading. This provided important insight on how such building constructions can have a beneficial or negative influence on a building’s power load. Conclusions have been drawn considering application of solar shading in Double Skin Façades and their operation strategies. Later on the gathered data formed the basis for conducting three sets of theoretical energy calculations, according to a simple method developed by the Bestfaçade Project Group, as well as three dynamic computer simulations in BSim. The aim of these tools is to provide a preliminary assessment of the impact of a Double Skin Façade on a building’s energy consumption, which might be used in the conceptual phase of a project. The obtained results have been compared with the measurements and both theoretical methods have been evaluated. Unfortunately, in most cases results from the theoretical tools gave values very different from reality. Finally, conclusions have been drawn including suggestions for improvement of Double Skin Façade and solar shading modelling methods.