Combined daylight and intelligent LED lighting - getting daylight into the buildings

The aim of the project was to develop and demonstrate a new concept of intelligent LED lighting which complements and follows the rhythm of daylight and thus bringing "daylight" into buildings.

The main results are the development of the new intelligent and dynamic LED lighting system, for demonstration and research purposes, and an extensive user test which has been completed, analysed and will be published at CIE’s one hundredth anniversary conference ”Towards a new century of Light” i April, 2013.

The LED lighting system is a full system for office lighting with celling fixtures and task lamps, which has facilitated the general and task lighting in two offices with two work places each. It has been installed in SBi’s daylight laboratorium. All lamps can be controlled via a developed computerinterface and the task lamps are further manually controllable by the user, with two knobs for color temperature and intensity.

The system is based on color mixing LED technology, and makes it possible to control the color distribution of the light, color coordinates, and hence the correlated color temperature of the light. The system is programmed for a possible change in color temperature from 2700 K to 6500 K. A mini-spectrometer is calibrated and built into the system, and measures the intensity and color temperature of the incoming daylight.

The results of user tests show that the developed possibility to automatically regulate the task light according to daylight color temperature is considered to be equally preferred and yields just as satisfied users as a traditional lighting system with even distributed lighting in the room. On the other hand the user test showed that both energy savings and more satisfied users can be achieved by giving users the opportunity to adjust either light levels or the color temperature of the light on the workspace and reduce the general lighting in the room.