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

In this paper, U-value variations of a fixed window were analyzed qualitatively and quantitatively. The factors which influence the U-value variation of a window when the window size changes are the ratio of the frame U-value to the glass U-value and the ratio of the frame size to the window size. The ratio of the frame size to the window size increases when the window size increases and the frame width is fixed. In this study, when the window size varies and the frame width is fixed, the effect of the ratio of the frame U-value to the glass U-value on the U-value variations of the window were investigated. The calculation of window U-value consists of the u-value calculation for the glass and frame and that at glass edge. When the window size varies, the U-value variation for the glass and frame and that of the edge of glass should be investigated together. When the ratio of the frame U-value to the glass U-value is bigger than 1 and the window size decreases, the U-value for the glass and frame increases against that of the standard test window. The U-value for the edge of glass increases when the window size decreases from that of the standard test widow. Therefore, if the frame U-value is bigger than the glass U-value and the window size is smaller than the standard test case, the U-value difference of the glass and frame and that of the edge of the glass from that of the standard test window are piled up together.