As mentioned in the introduction, large contrasts within the field of view are very unpleasant to the eye. This sensation is known as discomfort glare and has been examined from various perspectives since the early 1920s. Discomfort glare is usually expressed by a difference in luminance value within the field of view, and more precise by the ratio of the smallest and largest luminance value within the field of view. Although different researchers have formulated various equations with which to predict the discomfort glare, the agreement between the various equations and the subject response found by other researchers is still not so good that these equations are used in this paper. In this paper the simpler value of the maximum luminance ratio between the wall and the window is employed. This value, however, is also not so clearly defined as one would hope. In literature the following values are found, see table 1.

In this paper the value of 1:20 is taken as the maximum allowed value for the luminance ratio between the window and the surrounding wall. As this is not the maximum value found in literature, if a solution meets the demand of 1:20, it will always satisfy the higher demands found in the literature. As mentioned in the literature, the other parameters that influence the occurrence of discomfort glare from windows, besides the luminance contrast ratio is the lighting quality inside, the information given by the dagylight, the view through the window, the prior experience of the subjects and the subjects state of mind [1].