The market of daylighting systems is still growing, thus generating a need for evaluation and test procedures for the performance of the different systems. Two issues are crucial for the success of any integrated daylighting/controls system:
- User acceptance.
- Energy savings.
For the testing of the user acceptance two procedures have been developed and validated:
- Objective testing in office rooms equipped with the system.
- User assessments in a static virtual reality.
Both methods show that there is nothing like a "typical user", but at least two parameters seem to be crucial for user acceptance:
- View contact with the outside.
- Glare protection (especially for VDU workplaces).
For the energy savings prediction a combined thermal and lighting simulation procedure has been developed. A well-defined optical and thermal model has to be set up in advance. A suitable test procedure to get the models has also been designed. Some general restrictions of the simulation tools lead to a great effort needed to develop the models. With the simulation models, the energy performance of a well-defined case can be calculated. There is no general ranking of systems possible, as the ranking would be different under different boundary conditions. These conditions are:
- Geographic and climatic position of the building.
- The orientation of the rooms.
- Obstructions through buildings or trees nearby.
- Design of the room (especially the room depth, colours).
- Design value of the illuminance that is needed (e.g. office or floor).
- Occupancy hours (e.g. office hours or half day school).
- Whole year energy efficiency or seasonal accents (hotel, summer school).
For a lot of the available systems it is now possible to evaluate the important issues, such as user acceptance and energy savings.