To prevent the overheating of a well-insulated building in summer, facade elements with switchable U-value are a possible solution. A new translucent element with switchable U-value is presented. The convection around a translucent insulation panel is controlled by moving this panel vertically within the double glazing unit. Measurements of such elements show a possible switching of more than +100% of the U-value between the insulating and conducting state. Various geometries have been measured, and the influence of CO2 in the cavity has also been investigated. Based on the experimental results, TRNSYS simulations have been performed to investigate the overall performance of such a new element integrated in a real building. An optimized element could lead to a reduction of the cooling demand of up to 29.6% of the useful energy and to large improvements in the summer comfort. (C) 2014 Elsevier B.V. All rights reserved.