Fraunhofer Institute for Building Physics
Determination of daylight autonomy and lighting energy needs in rooms with different types of façade
As a general rule, complex measurements and calculations are required to determine the precise impact of different façades on indoor lighting conditions, artificial lighting requirements and the indoor heat gains that stem from lighting. These calculations are often too costly and time-consuming to perform in the initial stage of planning a building, yet many of the most important decisions concerning daylight availability are nevertheless made at precisely this stage of the process. This calculation tool has been designed to support the decision-making process. The program allows you to quickly compare different variants with tolerable deviations in order to identify the optimum solution at an early stage. It also provides you with a quick overview of the effects of different measures involving the structure (façade geometry, obstructions, etc.) and the engineering of the façade itself. The tool allows you to assess the quantities of daylight available for rough openings and calculate working figures for the relative operating times and daylight autonomy for 10 different façade systems. The annual energy saving potential can be determined on this basis, and it is even possible to calculate figures for lighting energy needs by specifying the installed output of the artificial lighting system and entering data on the type of lighting control system.