In the decision process of office building design it is important to take the effect of solar shading devices into account as they have a large influence on indoor climate and energy consumption. However there is often neither sufficient optical data available nor calculation tools that can determine the optimal use of solar shadings and their effect on indoor climate and energy consumption in a satisfactory way. Normally the optical properties are given as fixed values and the dependency of the specific combination with the actual glazing is not taken into account. Therefore a new calculation program, LightCalc, was developed. In combination with the program BuildingCalc, LightCalc simulates the performance of solar shading devices used in a building in a realistic way taking into account the variation of the optical properties over the day and year. The paper describes a user-friendly method, based on the use of the programs WIS and BuildingCalc/LightCalc, of how to evaluate the performance of different solar shading devices during an early design phase of a building. The window systems combining glazing and shading devices are characterized in WIS giving the transmittance and reflectance as functions of the profile angle. BuildingCalc/LightCalc allows to define a simple model of the building in which the windows systems characterized in WIS may be integrated. Heating, cooling, lightning and solar shading may be dynamically controlled and the energy and daylight performances of the building, as well as the indoor thermal climate, may be evaluated. A case study of a landscaped office building in which different solar shading devices are tested for two different cities (Copenhagen and Lisbon) is presented. Examples and suggestions of how to overcome the lack of information available about thermal and optical properties of solar shading devices are included in the paper.