Perceived spatial brightness when lighting up vertical or horizontal surfaces: Evaluation of Circadian Lighting

Until now, the focus in lighting design has mainly been on illuminating the areas and surfaces where visual functions must take place. Lighting design has therefore most of all been a practice in optimizing energy performance and compliance with rules. With the development of newer technologies in lighting control, it has become widespread that lighting not only aims to meet visual needs, but also stimulates other non-visual human factors.

The purpose of this report is to evaluate and to generate knowledge about perceived spatial brightness by illuminating vertical or horizontal surfaces. The intention is to get closer to a clarification of whether and how much the light on the horizontal plane can be reduced by
compensating with light on vertical surfaces so that perceived spatial brightness is still the same.

In this respect, the report is particularly interesting for lighting designers and other professionals working with lighting systems.
The evaluation is performed by BUILD - Department of the Built Environment, Aalborg University with input and great help of various kinds from project partners in relation to the project "Dynamisk Døgnrytmelys" (In English: Integrative Lighting). Special thanks to the staff at AFRY who participated in the tests at their location.

The project "Dynamisk Døgnrytmelys" has been carried out with support from ELFORSK,
PSO-project no. 351-041.