Daylight linked dimming: effect on fluorescent lamp performance

Abstract

Using automatic lighting control it is possible to utilize daylight and thus reduce the use of artificial lighting energy. However, a control system based on daylight makes great demands on lamps and ballasts. A lamp life test was used to study the effect of dimming on lamp life and the lumen maintenance of fluorescent lamps. Lamps were dimmed statically to a 1%, 5% or 15% luminous flux level or dimmed dynamically up and down thus simulating dimming according to the daylight illuminance. The results show that with electronic ballasts, lamps will reach the nominal lamp life even if the lamps are dimmed according to the daylight illuminance. When lamps burn continuously at low dimming levels, the lumen maintenance factor is larger than when lamps burn undimmed. The effect of dimming on lamp life and lumen maintenance factor is thus not an obstacle to the combined use of daylight and artificial lighting.