On the Impact of Integration of Non Image Forming (NIF) Effect of Light on Electrical Lighting Control in Non Residential Buildings
Lighting has an impact on the visual as well as cognitive performance of people in non residential buildings. Light is the most powerful time cue for resetting the circadian pacemaker and ensuring correct synchronization of the internal clock with the environment: these effects are called "Non Image Forming" (NIF) functions. The expected neuroendocrine and neurobehavioral responses of subjects to light exposure can be summarized in four principal categories: alertness, sleep quality, mood and performance. The properties of light such as intensity, timing, pattern and light history influences neurobehavioral responses. These significant effects of light are currently not considered in building automation mainly due to the unknown and complicated nature of NIF effects as well as lack of proper technology. This leads likely to a considerable loss of productive time and momentum for the office occupants. This paper explores the existing knowledge of NIF effects of light on human beings and consequently proposes a novel dynamic lighting pattern, which is used as a set point for an integrated daylighting and electric lighting system. In other words, the existing scientific knowledge of NIF effect of light is introduced into the lighting engineering and automation domain. This user centric approach allows for a system level study of the suggested variable lighting set points. A novel High Dynamic Range (HDR) vision sensor installed next to the office user allows for an 'on the fly' evaluation of the light flux received by the human eyes during daytime: it also offers a personalized, refined control of an integrated electric lighting and sun shading system.