Retinal illuminance from vertical daylight openings in office spaces

M.B.C. Aries and S.H.A. Begemann, Eindhoven University of Technology
L. Zonneveldt, TNO Building and Construction Research
A.D. Tenner, Philips Lighting BV, the Netherlands

Keywords

light, daylight, electric light, retinal illuminance, vertical illuminance, horizontal illuminance, biological stimulation effects, mood, well-being

Abstract

Light entering our eyes (ocular light) not only enables us to see. It is now clear that biological stimulation via ocular light is important for our health, well-being and ability to perform. This paper presents the first results of a comprehensive research project to characterize and develop healthy office lighting that will meet both visual and biological stimulation needs.

For different working planes in a standard office room a person is simulated in an experimental set-up at eye-height (1.25m) sitting at a desk, viewing in different directions. The measurements took place for three types of lighting conditions: daylight only, electric lighting only and a combination of daylight and electric lighting.

Daylight entering through a vertical window has a very strong vertical illumination component, as opposed to a ceiling based electric down lighting system, as is widely used in offices. The ratio Eret/Ehor is influenced mostly by daylight. In a situation with electric lighting luminaire layout and photometric distribution are important.