Empirical Analysis of the Effects of Window Remodeling using the Slim Double-Skin Window on the Thermal Performance of Old Buildings

Building energy consumption accounts for 30% of the total global energy consumption and is increasing every year. Improvement in the heat transfer performance of the building envelope to reduce energy consumption is a current research hotspot. In the present study, we investigated the performance of the slim double-skin window (SDSW) via empirical analysis. The effect of SDSW-based window remodeling on the thermal characteristics of an old building was investigated with a life-size building. Empirical analysis compared the changes in thermal characteristics between the conventional windows in the old building and the remodeled SDSW. Glass and frame temperature, envelope airtightness, indoor heating environment, and cooling energy consumption were measured before and after window remodeling, and the extent of the influence of external environmental factors, such as insolation, outdoor temperature, and wind speed, on these properties was compared and analyzed. The results show that compared with conventional windows, the SDSWs were less affected by external environment-associated factors, such as sunlight and temperature, thereby maintaining a more comfortable indoor heating environment. Furthermore, the annual building energy consumption was reduced by 34.2% with the use of SDSWs, compared with that of conventional windows.