건물에너지 절감을 위한 폐열 발전 및 자연채광 적용에 관한 연구

Abstract

Climate change due to global warming and depletion of existing fossil fuels are calling for the development of renewable energy and increasing use of energy efficient technologies. Unfortunately many modern buildings, these days, have hired a rather stereotypical architecture design where major portion of a building envelope is more or less covered with glass windows for aesthetic appearance. As a result, energy consumption due to indoor air conditioning and lighting in buildings is increasing. In this study, two different techniques were applied and their effects were examined to reduce energy use in buildings. The first is the use of low heat source TM (Thermal to Mechanical) power generation technology to produce electrical energy using low temperature waste heat (about 60 degrees) discarded by various HVAC systems in buildings. The second is a comparative analysis using a simulation model of fluorescent lighting and Fresnel lens based fiber optic lighting. These techniques deems to have great potential in saving electric energy consumed in buildings as well as alleviating rising environmental problems. 1. Low heat source TM(Thermal to Mechanical) power generation To harness low grade thermal energy a single and twin type MM-7 engines were tested, which have been known as one of the most efficient ways to draw any power from a small temperature difference between two heat sources. The experimental results of the MM-7 engines were compared with gadolinium-based power generation system as the latter produced greater torques under the same thermal conditions. As for the MM-7 Stirling engines, the power output of the twin engine showed the highest value as long as the engine could handle the weight used to measure torques. As the mass increased beyond a certain value, it ceased to operate because the power generated was smaller than that produced by weight. In comparison, the gadolinium-based power generation system produced the maximum mechanical output of 20.09mW at △T=40℃. This was about 3 times higher than that of LTD Stirling engines. 2. Simulation of facility type daylighting system In order to deliver the actual conditions in building energy simulation concerning indoor lighting conditions, simulation conditions were set based on the physical dimensions of actual windows and blind usage patterns of the building. ECOTECT was used to model the test room (space) while Radiance was used to carry our its indoor lighting conditions (environment). A series of experimental results show the validity of the Fresnel based daylighting system in saving energy used for indoor lighting. This was clearly demonstrated by comparing its energy consumption if the indoor lighting was solely furnished by fluorescent lamps. It was projected that 590,000 won could be saved over the period of 30 years if the daylighting system could be consistently employed during the daylight hours.