Switchable facade technology - energy efficient office buildings with smart facades

This paper describes describes the energy performance of switchable façade technology using electrochromic and gasochromic windows in a office environment. Heating, cooling and lighting energy are affected by the dynamically changing optical properties. Starting from angle-dependent laboratory characterisation, a validated façade model is being used in coupled daylight and energy simulations. The methodology and results for different European climates are presented. Switchable facades have a similar potential reducing cooling loads as external shading devices, however with different visual and practical consequences. User can always look through a deeply coloured glazing whereas for external solar protection the view can be obstructed. The solar protection function is integrated in the glazing in one single building element, and it cannot be affected by wind. Thus the emerging technology seems to have good prospects on a future market, provided the longterm reliability can be demonstrated soon.