TaHo - Energy-efficient and cost-efficient daylight lighting using micro-optical building components

Daylight control using new micro-optical structures
© Fraunhofer IBP
Daylight control using new micro-optical structures in the façade/window area and on the ceiling in a classroom of the “Krefeld School” demonstration building.

Micro-optical components for daylight utilization and sun shading can significantly improve energy efficiency, life cycle assessment and quality of life in buildings. A structure for vertical façades has already been pre-developed in dimensions suitable for building applications that directs daylight to areas deep inside a building without glare. This is currently being tested in demonstration buildings. Research is being carried out into new structures for effective sun shading in skylights.

Project goals

In the previous BMWi-funded project “TaLed – Energy-efficient and cost-effective LED and daylight lighting integrated into façades using micro-optical building components, 03ET1330A-G”, a light-directing structure for vertical façades was developed, which is now available in dimensions suitable for building applications. In Part A of the project, these were further optimized for practical use in two demonstration buildings (school building and office building), where their energy efficiency and user acceptance were tested and evaluated in a monitoring process. In parallel, instruments were developed to support the market launch. Project Part A thus paved the way for the practical introduction of the new structure.

In Part B of the project, new micro-optical structures were developed for the other key building application in daylight utilization - the natural illumination of building structures via skylights and horizontal glazing. In terms of aspects such as efficiency and potential for mass production, these should be comparable with the structure for vertical façades. The core task of this development was to optimize the relationship between daylight entry and sun shading while ensuring a high level of visual comfort (glare control). This has been achieved without the use of cost-intensive mechanical tracking systems for sun shading structures. Two potentially suitable optical structures were initially developed with the aid of simulations. Due to the different irradiation angles and the resulting increased requirements for light/radiation guidance, the optical principles developed in previous projects based on TIR (Total Internal Reflection) were supplemented by partially mirrored surface elements. Manufacturing processes were further developed accordingly. At the same time, methods and characteristic values were derived to differentiate them from current market solutions (skylight domes and strips) as regards energy assessment and visual comfort. The first glare assessment approaches were tested. The work was accompanied by the development of concepts for integrating the micro-optical structures from an architectural point of view. 

Project result

The first results are expected in spring 2024.

Project partners

  • Green Building R&D GmbH, Düsseldorf
  • Karl Jungbecker GmbH, Olpe
  • Technical University of Dortmund
  • SSP AG, Bochum
  • Temicon GmbH, Dortmund
  • Durlum GmbH, Schopfheim
  • Okalux Glastechnik GmbH, Markheidenfeld
  • Kassenärztliche Vereinigung Westfalen-Lippe, Dortmund
  • City of Krefeld   
Optimized daylight entry using light-directing microstructures
© Fraunhofer IBP
Optimized daylight entry using light-directing microstructures in an office in the demonstration building.
Development of new angle-selective, retro-reflective, micro-optical structures for roof skylights and horizontal glazing
© Fraunhofer IBP
Project Part B: Development of new angle-selective, retro-reflective, micro-optical structures for roof skylights and horizontal glazing. Miniaturization and thus cost reduction as a further development of the established shed skylight principle as a purely structural roof design