Advanced daylighting technologies integrated with efficient electric lighting systems can contribute to mitigate the energy demand of buildings while simultaneously improving users thermal/visual comfort and performance. A High Dynamic Range (HDR) vision sensors, developed by the Centre Suisse d’Electronique et de Microtechnique (CSEM), was photometrically, spectrally and geometrically calibrated in order to be integrated in a shading and electric lighting control system. The device allow for real-time capturing and analysing of luminance maps of visual scenes, with considerable accuracy and speed thanks to a logarithmic intra-scene dynamic range, a range larger than the one of human eyes. A powerful system-on-chip (SoC) platform (32-bit DSP processor, 500MHz) allows performing concurrent image processing. As a result, the device allows ‘on-the-fly’ monitoring of luminance in a working environment as well as a glare risks assessment based on the Daylight Glare Probability.
The integration of High Dynamic Range (HDR) vision sensors in a sun shading and electric lighting control platform has been carried-out during Phase I. Two identical sensors were used to measure two photometric variables in a workspace: (i) the Daylight Glare Probability experienced by the user located in the workspace and (ii) the workplane horizontal illuminance. The first sensor is placed as close as possible to the user’s viewpoint; the second one is mounted on the ceiling. A control platform was set-up to guarantee the proper data acquisition and logging, flawless initialization as well as actuators commanding. The platform was installed in two identical office rooms of the LESO solar experimental building on the EPFL campus. A data acquisition and actuation system, driving two motorized sun shadings per office, a dimmable LED lighting system, a user presence detector, energy meters as well as two HDR vision sensors were set-up for that purpose. An adjacent office room equipped with a ‘best practice’ LED lighting controller (e.g. a daylight responsive dimming system) was used as reference room. The ‘on site’ monitoring data indicates that the electricity demand of the advanced system installed is lower than the reference one. It also shows that the users visual comfort and performance expressed by 30 human subjects remains comparable in the two office rooms. Last but not least, the advanced control system based on the HDR vision sensors was successful in preventing discomfort glare sensations in the corresponding office room.
The current HDR vision sensors (lab edition) will be further improved (market edition) with the collaboration of CSEM to provide similar integrated lighting controllers in daily life in collaboration with industrial partners such as Regent Lighting AG and Griesser Storen AG.
For more information, please contact Prof. Jean-Louis Scartezzini, EPFL.