[o3u]-cam4BSDF – BSDF measuring device with [o3u]-cam (camera)
Project Manager Overall Project: Wilfried Pohl, optical design unit gmbh
Project Leader: David Geisler-Moroder
Project Partner Austria: optical design unit gmbh
Funding Agency: The Austrian Research Promotion Agency (FFG)
Funding Program: Expedition Zukunft - START - Business Edition
Project Period: 01.07.2025 to 30.06.2026
Summary
Well-planned daylight and solar shading not only have a direct impact on the need for artificial light, but also influence the heating and cooling loads in buildings via solar gains. The availability of natural daylight not only saves energy, but also promotes the well-being and health of users and increases motivation and productivity.
However, the potential of these systems can only be realised if they are used in a correctly planned manner, for which the availability of BSDF data is essential. BSDFs (bidirectional scattering distribution function) describe how incident light, e.g. solar radiation, is scattered, reflected and deflected. This information is essential to characterise the function of the systems so that they can be incorporated into building simulations.
BSDF data is currently not available in practice. They are currently only generated in the course of scientific research projects, with the help of complex and outdated measurement set-ups at research institutes, of which there are only a few worldwide. The measuring principle is that the radiation in the entire solid angle around the sample is recorded for all directions of incidence. Order measurements are associated with long measurement times and high costs, and the angular resolution and dynamic range (measurement accuracy) are insufficient to capture images of the sun.
For these reasons, BSDF characterisation is not used in practice; there is a gap in the construction process that prevents up-to-date digital recording of shading and daylighting systems.
As part of the FFG-funded life science project ‘Operating theatre light’ (Proj.Nr. 903767), o3u has developed a new camera-based measuring device for the photometric measurement of luminaires and optical components, the so-called [o3u]-cam ©. In comparison to commercially available goniophotometers, the measuring device is small, a measurement only takes a few seconds and the angular resolution of 0.05 degrees is significantly higher.
The aim of the project is to test the technical and economic feasibility of a new [o3u]-cam-based measurement method for characterising sun shading and daylight systems that allows fast and cost-effective measurements of the BSDF.
If it is possible to measure standardised BSDF data of solar shading and daylighting systems cost-effectively and with sufficient accuracy so that these systems can be planned with the corresponding building simulation programmes, this will represent a revolution in the building sector.
The building market will change: this new ‘predictability’/plannability will bring sun shading and daylight technology more into the focus of all those involved in construction, and the integrative planning of façades, sun shading, artificial light and daylight, heating and cooling and energy will be accelerated. There will be an increasing demand from the industry for multifunctional systems that not only solve sun protection or building lighting, but all aspects simultaneously.
These activities will mean that the potential of daylighting and solar shading technology (building envelope) will become calculable and plannable, and that the demand for such systems will rise sharply. Ultimately, the energy efficiency and sustainability of buildings will be significantly improved.