Energy-saving Renovation of Kyo-machiya Considering the Moisture Buffering Effect of Soil Walls

Abstract

Kyo-machiya, a type of traditional townhouse in Kyoto, is considered as cultural heritage that needs to be preserved. However, the high air leakage due to its unique structure and poor thermal insulation because of its traditional appearance may lead to high heating energy consumption. Therefore, an appropriate energy-saving renovation technique is proposed. However, the lack of quantitative analysis hinders the establishment of effective renovation guidelines focused on the energy-saving and healthy indoor environments of Kyo-machiya. Previously proposed retrofits were conducted using conventional methods with limited effectiveness. The soil wall in Kyo-machiya has an impact on indoor environments and is considered as a significant feature, and its appearance is crucial for the residents. Also, the soil wall has a moisture-buffering effect. Therefore, the adoption of interior insulation should be considered with caution. In addition, high air leakage is not fully resolved via the conventional methods. In this study, we used a numerical model of a typical traditional Kyo-machiya to evaluate different renovation designs, including interior and exterior insulation, vapour/moisture proof solutions, and effectiveness of enhancing air tightness. Finally, we proposed a renovation plan based on the conventional methods, considering the balance between energy-saving and hygrothermal risk.