Automatically controlled daylighting for visual and non-visual effects

This is a study of daylighting in an automatically controlled office environment. The objective is to identify any correlations between horizontal and vertical illuminances and to determine if daylight controls can be applied to predict and regulate both illuminances. Two sets of real-time measurements were made, complemented by computer simulations. The results showed that the vertical illuminance at the eye depends on the portion of sky in the visual field. The average ratio between vertical and horizontal illuminances was relatively constant at 1.5, even though the external sky conditions were variable. This implies that the vertical illuminance at the eye can be predicted with acceptable level of accuracy if the horizontal illuminance on the working plane is known.