The Impact of Window Form on the Size Impression of the Room—Full-Scale Studies

Full-scale studies of a small room were carried out at Norwegian University of Science and Technology, Norway, to find out in which way the form of window(s) influence the size impression of a little room. Care was also taken to find out if the impression is due to the form of the window alone, daylight falling through it, or to both. The results indicate that the impression of room dimensions depends on window form, even if the total glazing area is equal. Generally, vertical windows make that the room appear higher, horizontal make it wider. The visual impression of the room depends also to a high degree on the placing of the window in relation to the neighboring surfaces: sidewalls, floor and ceiling. The window adjacent to a sidewall contributes to higher luminance of this wall, it appears as being further away from the observer; the room appears as wider. The same principle is true for windows adjacent to the ceiling or floor. They contribute to increasing the impression of height. The study was carried in rooms having high reflectances on all surfaces, the enlarging effect of the window adjacent to the neighboring surface may not be that clear in rooms having dark surfaces.