Active–passive combined energy-efficient retrofit of rural residence with non-benchmarked construction: A case study in Shandong province, China

Unlike standard-restricted and well-equipped urban residential buildings, a large portion of rural buildings sacrifice indoor comfort and energy efficiency to reduce the initial investment. Therefore, cost-effective retrofit strategies for rural buildings are urgently needed to better living conditions and create higher energy efficiency. This study developed a framework to choose the optimal economical retrofitting strategies for existing rural buildings by taking both active and passive approaches into consideration. The building retrofitting measurements were a combination of thermal performance improvement for external walls and a solar photovoltaic generation system for the rooftop. With the case of a rural dwelling in Shandong province, this study first assessed the thermal transmittance of the external walls and collected geometry and operational schedules to create a building model for the later energy simulation. Environmental monitoring was also conducted for two months – in February for winter and August for summer – to obtain actual indoor temperatures, which were used to calibrate the energy model within a 10% error rate. In total, 17 retrofitting plans were then set up and analyzed in this study. The results showed that when applying the cost-optimal retrofit plan, there is the great potential to reduce energy use by 20.5% and to balance the annual building energy consumption with a payback period of 10.7 years. Finally, the proposed framework was proven to be accurate and feasible and was expected to be widely used in the improvement of living conditions in Chinese rural areas.