This study began because of the necessity to know how the traditional light well works and arrive to a simple rule that architects can apply at the moment of designing buildings, mainly multi-storey apartment buildings, in which except for bathrooms, all rooms need an outdoors relation. This is important not only because it involves architectural problems but also legal ones, we don’t have to forget that light wells are usually common areas in multi-storey apartment buildings and each one of the apartment owners has rights over them, for this reason, the simplest solution would be the best. Some of the conclusion from this investigation were: A compact form of the light well is the best way to optimize daylighting. Both sides of light wells provide the same illumination for their windows despite the proportion of the sides. One big light well provides better illumination rather than many small light wells that sum the same area. These conclusions can be taken as considerations architects can use at the moment of designing because they give a simple tool to proportion light wells and design the rooms around them. Also, this study arrives to other conclusions, first that it is not possible to use a rule of three in order to study daylighting with scaled models; and that the decay of illumination inside light wells is not constant, there is a small decay in the top and a very pronounced in the bottom. Those conclusions are important because this work was thought to be the first step for further experiments with much more sophisticated models and equipment, and also more expensive, so a well-done budget based on the design of models on bigger scales is needed. Although nowadays the use of computer simulations in order to study daylighting has many advantages, such as cost and time, the most reliable conclusion can only be obtained from an experiment because as it was known since the first days of computing, the machine only will solve the equations and follow the program, it will depend on the data and the program gave by humans if the result is correct.

Keywords : Light Well, Void, Courtyard, Daylight, Scaled Models.