Architectural aspects of healthy lighting

Recent discoveries on the effects of light on human well-being lead to new demands for lighting solutions. In addition to the visual comfort criteria (e.g. sufficient task illuminance, absence of glare) additional non-visual criteria are being formulated. Non-visual effects of light include influences on the biological clock and direct stimulation of the human brain. Triggering of these effects occurs through recently discovered receptors in the human eye. In this process the vertical illuminance at the eye is a key factor. Also the dynamics of light in terms of intensity, spectral composition and direction during the day play a role. Because the vertical illuminance at the eye is the dominant parameter in healthy lighting in design of architectural spaces special attention must be paid on vertical (il)luminances. Current electric lighting installations for instance only provide horizontal task illumination. Daylight through vertical window openings is potentially a much better source for healthy lighting. In the Knowledge Center Building and Systems TNO-TU/e ongoing research is taking place to determine human lighting demands and the find suitable and sustainable solutions. An example demonstrates solutions that satisfy the traditional demands for visual comfort and performance as well as the additional demands for well-being, alertness and productivity. Solutions include the use of advanced daylight systems, low energy electric lighting and electronic controls.