Are the results specific to the particular luminaires used in the study?
In the case of the parabolic system, the answer is “no” with minor qualifications. Regardless of the sophistication of its design, direct parabolic downlighting provides a cone of light from an otherwise dark ceiling. Direct lighting creates direct shadows, contrast between the fixture and the ceiling and an environment that is more brightly lit within the cone of light than outside it. The answer is less clear-cut in the case of the indirect system. There is great variation in the ability of indirect lighting systems to distribute light across a wide area. An indirect system like the systems used in the study will provide a superior luminous environment if it can produce even luminance ratios across the entire ceiling. However, one with poor distribution will produce hot spots on the ceiling bright enough to cause contrast and shadow problems similar to those created by downlights. Substituting a lesser system for the one used in the study could have created considerably different res
