Energy-saving potential of deeply retrofitting building enclosures of traditional courtyard houses

It is increasingly believed that energy retrofits are a protection tool to preserve cultural heritage for future generations. However, few studies are available regarding the deep retrofits of traditional courtyard houses in the Chinese Hot-Summer-Cold-Winter zone, although the winter conditions in these buildings are very uncomfortable based on existing studies. Besides, few studies analyzed the actual energy performance of still-occupied traditional buildings in this region. Therefore, this study investigated the energy-saving potential of deeply retrofitting the building enclosures of a traditional courtyard house in Tongren in southern China. The investigation was based on calibrated hygrothermal simulation with WUFI®Plus applying the multi-zone airflow modeling. For the calibration, short-term monitoring (two weeks) was conducted in winter and measured the air temperature, relative humidity, and heating energy consumption. The calibration showed satisfactory results by assessing the Normalized-Mean-Bias-Error, the Coefficient of Variation of Root-Mean-Square Error, and the Coefficient of determination. In contrast, the application of Goodness of Fit shows poorer performance and requires further discussion for short monitoring periods. According to this study, improving the U-values of building envelopes to meet at least the current Chinese energy-efficiency standard can reduce more than 56% energy demand for heating and cooling, with an estimated payback time of 2.5 years for the material cost. With growing expectations of building occupants on indoor thermal comfort, the improvement of the energy performance of traditional buildings will become more critical for their long-term preservation and should be implemented in China’s energy efficiency policies and initiatives in the future.