Daylighting museum galleries: a review of performance criteria

Conservation-based restrictions on light levels and cumulative exposure in museum galleries are now well established. These have resulted in restrictions on the use of daylight and prolonged development of systems to deliver and control its admittance. Attempts to control daylight and deliver fixed illuminance levels have proved difficult to sustain. Recent installations, in the 1980s and 1990s, have become reliant on a proportion of electric lighting during most opening hours and an acceptance of limited daylight variability within dosage recommendations. Given the difficulties in estimating and measuring dosage, most museums have limited data on their actual lighting performance, and guidance is sparse on how such targets can be met. This paper reviews the limited goals widely referred to in guidance to designers and presents typical data drawn from monitoring in the Frick Collection, New York. The balance between electric light and daylight is discussed in the context of an interior's daylit sensibilit...