A lightwell is a daylighting design that brings daylight (including sunlight and skylight) to the lower floors in a multistorey building. A lightwell has a similar function to a lightpipe or an atrium, but its size is medium. This paper presents construction, measurement and RADIANCE simulation of a model lightwell. The model lightwell has a scale factor of 1:20 to simulate a real lightwell design for a multi-storey hotel. The model lightwell has the dimension of 100 mm (width) x 150 mm (length) x 800 mm (height) contained in a six-storey model building section with a dimension of 400 mm x 500 mm x 800 mm. Comparison of the measured daylighting performance is made for two different inner surfaces (matt white paint and mirror-finish) of the model lightwell under overcast and sunny sky conditions, respectively. Computational analysis on the daylight factor (DF) or illuminance ratio provides essential information to determine key design parameters and applicability of a lightwell. Copyright (C) 2010 John Wiley & Sons, Ltd.