Abstract
To secure high productivity and a comfortable environment in office space, lighting is one of the most important factors in architectural design. The purpose of this study is to discover the important factors in the quality of room illumination, by making field measurements in typical office buildings with different uses and design. The buildings examined were an energy conservative building, a high rise building and a computation center building. Analysis of these field measurements has revealed that the important factors concerning the luminous environment are the illuminance on the workplane and its distribution, the appearance of lighting fixtures and their layout, balance of brightness in a room and the contrast of brightness between window and wall surfaces. The results of measurements of the illuminance, luminance, contrast rendering factor, cylindrical illuminance and reflection factor have revealed that uniformity of illuminance and discomfort glare are below that required by Japanese standard JIEG-004-1983, and international recomendation CIE TC-4.1. Comparing the illuminance of vacant spaces (i.e. not installed with office supplies) and that of occupied spaces, significant differences were observed in the average illuminance. The latter is smaller than the former by approximately 20 %. This fact should be considered when using the conventional flux method in room lighting design. Lighting design method based on the luminance concept in addition to the conventional illuminance figure will be required for the design of office space in the future. The occupants opinions about the level of comfort should also be studied when a lighting design method is considered.
