The Design and Performance of a Permanently Mounted Daylighting Device

Abstract

A new design for a daylighting device is described and some initial experimental results taken in a model room are presented. A major feature of the design is that it has a wide acceptance angle of greater than 50°. This means that it can be permanently installed in a window aperature and redirect light towards the upper back part of the room, whether the sun is low in the sky (elevation around 20°) or high (75° or more). Initial measurements in the model room show daylight illuminance levels deep in the room can be increased by factors of up to 6 times values achieved using an ordinary window of equivalent size. The resulting illumination can be more than sufficient for many tasks and apart from creating a more pleasant environment, offers the potential to make significant savings on electricity usage in buildings with large daytime use.