Visual and Thermal Performance of Natural and Artificial Luminaires

Using light pipe technology as a daylighting strategy offers considerable advantages because daylight can be transmitted virtually to any space inside the building. Its simple structure is an additional advantage as it is aesthetically acceptable and harmonizes with building environment. Switching to daylighting for interior lighting during daytime means great saving in total electricity consumption in buildings as well as good long-term money saving to consumers. This paper reports on the visual and thermal performance inside a test room, in particular under tropical climatic conditions, due to different lighting systems. The measurements of illuminance level and air temperature for both indoor and outdoor were carried out simultaneously over a certain period of time. For comparison purposes the study was divided to three cases, which were categorized by different lighting strategies or luminaries used inside the test room. In the first case, the room was totally illuminated by natural daylight from a light pipe, while in the second case, illumination was provided by artificial lighting using two 36W-fluorescent lamps. In the final part, the same measurements were made when the room was illuminated by daylight from window openings. In all three cases, measurements were carried out continuously from 7:30 hrs to 18:30 hrs. It was found that the light pipe performed best in terms of visual quality and thermal impact inside the test room.