Active solar shading

Windows of a building is generally known to increase the use of energy if the lighting system is not carefully co-designed with window and solar shading system. Usually, it is not, and the window acts as a piece of wall with lack of insulation most of the year and as a heat gain raiser part of the year, usually increasing both annual heating and cooling energy use. If it is assumed that a certain window area is the case, due to architectural reasons or other, it is not an alternative to change the window area. Solar shading can be used to decrease the cooling power demand and energy use but that also reduces the possible benefit for heating with the solar gain. The apparent solution is to shade when there is a cooling need and gain when there is a heating need. This paper presents measured data and energy use calculations on such a system set up in an office in southern Sweden. The result shows that the energy use can be reduced remarkably compared to a case with fixed solar shading.