The Luminance Differences index: a new indicator of user preferences in daylit spaces

This paper presents part of the findings of a research project conducted at the Martin Centre University of Cambridge, which looked into how daylighting quality affects the users of a library interior. It discusses the importance of luminance in the field of view for the perception of quality and introduces a new index named Luminance Differences (LD) which represents luminance variability (‘noise’). It will be illustrated that this index was successful in relating to the users’ subjective assessments of daylight quality, suggesting that it can be used to predict user preferences in a daylit space.