Measurement and RADIANCE Simulation of a Model Lightwell

A lightwell is a daylighting design to bring daylight to the lower floors in a multi-storey building. This paper presents the construction, measurement and RADIANCE simulation of a model lighwell. The model lightwell has the dimensions of 100mm (Width) * 150mm (Length) * 800mm (Height) and an outer envelope of 400mm*500mm*800mm devided into six floors. Scale-up of this model by 20:1 gives alike size of a real building. Use of matt white paint and mirror-finished surface as the lightwell wall is compared in the measurement under the overcast and sunny sky conditions. The Daylight Factor or illuminance ratio is given to assess the design of this model lightwell. The measured results are used to compare with RADIANCE simulation. The RADIANCE simulation is also used to give Daylight Factor distribution and assist the optimal design of the lightwell including the effect of the lightwell dimensions and glazing cover.