The purpose of this study is to examine the relationship between “visibility from inside” and “estimated visibility from outside” and the factors that affect “visibility from inside” in various lighting environments and windows in order to predict visual privacy. From the results of experiments in actual housing complex and the laboratory, it was found that the linear relation between “visibility from inside” and “estimated visibility from outside” was established for all types of window treatment. The relationship is unaffected by lighting condition, window shape, or evaluation position. However, this relationship is only valid when the outdoor illuminance ≥ indoor illuminance.
