Journal of Korean Institute of Architectural Sustainable Environment and Building Systems ISSN:1976-6483(Print) 2586-0666(Online) 한국건축친환경설비학회논문집

Highly efficient window systems have been consistently demanded since the amount of heat exchange through windows is significant. In particular, the large amount of solar heat gains through the south-facing window of the living room during the summer season is the main culprit of the increase in cooling load. Electrochromic window (ECW) can be an effective solution to this. We found out that there is few prior study which has applied ECW to residential buildings and has made comparative review of various environmental factors for ECW control. Therefore, in this study, we applied ECW to an apartment unit and evaluated the energy saving potential of ECW by various environmental factors for ECW control such as incident solar radiation on vertical surface, daylight illuminance, indoor air temperature and outdoor air temperature. As a result, applied with ECW, solar heat gains through the windows decreased by about 60% on average, resulting in an average reduction of about 25% and 13% in cooling energy use and cooling peak load, respectively. Among the environmental factors, daylight illuminance was most effective in reducing cooling energy use (-32%) and cooling peak load (-15%). Comparing the cases of different orientations of ECW, it was shown that there was not much additional energy savings when ECW is applied to both Southward and Northward windows. Moreover, the result indicates that when the occupants are not at home during the daytime, ECW should also be operated as the varied occupants schedule to save cooling energy more effectively.