Experimental Investigation of Top Lighting and Side Lighting SolarLight Pipes under Sunnny Conditions in Winter in Beijing

摘要

Natural light is very important element in the quality of vision.Solar light pipes are effective method to inducesunlight into the room need to be illuminated especially for corridor, some places natural sunlight cannot arrive. Solarlight pipes are also effective ways to reduce electricity consumption for lighting; it can transmit sunlight from outdoor tothe room without generating excessive heat. The performance of two top lighting solar light pipes and one side lightingsolar light pipe were investigated at the same time under sunny conditions in winter in Beijing. The results showed thatside lighting solar light pipes have better performance than that of top lighting one. Side lighting light pipe has betterperformance than top lighting light pipe if there are no shelters around the top dome under sunny conditions in winter inBeijing. Solar altitude is the main reason to give an effect on the performance of light pipes. The experimental resultsalso showed that top lighting solar light pipes with "snow type" diffuser has better performance compare with the"diamond type" one. Solar azimuth can also affect the illuminance for whole day to all solar light pipes. So if thesunlight collector can following with the sun, this problem can be resolved, that is ,automatic sun trackers are needed,but the cost will become too much at the same time. Different regions and different seasons had to select different typesof solar light pipes to achieve maximum output of illuminance in the room. Design of the solar light pipes must adjustmeasures to local conditions. Solar light pipes will be popularized in the near future in China because have manyadvantages to improve energy efficiency in buildings.