Qualitative and quantitative daylight façade planning for a consulting practice

lighting conditions
© Fraunhofer IBP
Calculation of indoor lighting conditions.
Simulation result for daylight functionality
© Fraunhofer IBP
Integration of daylight functionality in DIALux evo.

The aim of the project was to improve qualitative and quantitative lighting and energy-efficient façade planning in a consulting practice by providing suitable planning tools. This should reduce planning errors, improve the integration of plans for daylight and artificial lighting and increase planning quality.

Both measurement and software engineering work were conducted out in the course of the project. The existing goniophotometer at Fraunhofer IBP was extended to enable measurements on façade elements to be carried out. The goniophotometer records not only the transmission of light through façade elements but also the light reflected by them (indicatrix of diffusion of the luminance coefficient, also known as bidirectional reflectance distribution function or BRTDF) with spatial resolution. These measurement data are used to calculate the luminous intensity distribution curves of different façade systems (sun shading, glare protection systems, daylighting systems, roof skylights). The DIALux evo software for calculating light propagation in all types of building structures has been supplemented by additional functions to enable use of the above-mentioned luminous intensity distribution curves.


  • Extension of the Fraunhofer IBP goniophotometer
  • 51 different systems have now been measured, meaning that data on a wide range of façade elements is now available to the planning community.
  • Integration of the façade algorithm into the free DIALux software with more than 600,000 users worldwide
  • User-friendly data plug-ins in DIALux evo


The project was funded by the German Federal Environmental Foundation, (Az. 30734-25)

with the support of the companies: Warema | Indulight | Siteco | Lamilux | SIH - Le Haras | Hella | Essmann

Project partners:

DIAL GmbH, Lüdenscheid | FH Rosenheim | Ratec erneuerbare Energien

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Measuring and testing facilities at IBP