Building simulation as an assisting tool in decision making: Case study: With or without a double-skin façade

Implementation of double-skin façades in buildings has been an object of broad application in the recent years. In this presentation, a planned office building in the city-centre of Trondheim, Norway, is used as a case for considering whether a double-skin should be applied to the east façade in order to reduce the heating demand, thus making the double-skin façade a profitable investment. The building is modeled both with and without a double-skin façade with the building energy simulation program ESP-r. This paper describes how a double-skin façade with controllable windows and hatches for natural ventilation can be implemented in the simulation program. The simulation results indicate that the energy demand for heating is about 20% higher for the single-skin façade with the basic window solution compared to the double-skin alternative. However, by switching to windows with an improved U-value in the single-skin alternative, the difference in energy demand is almost evened out. The number of hours with excessive temperatures is, in contrast to other studies on the subject, not significantly higher for the double-skin alternative. However, the predicted energy savings are not sufficient to make the application of a double-skin façade profitable.