Rural heat island effect of centralized residences in China: Mitigation through localized measures

China has implemented a Centralized Rural Policy since 2004 to enhance energy efficiency. However, this has led to the potential creation of a Rural Heat Island (RHI) effect, which could diminish outdoor thermal comfort and increase building energy consumption during hot summers. While most studies on heat island effect focus on spatiotemporal variations and heat mitigation measures, there is limited research on rural areas, particularly the special layout of rural residences. Additionally, most studies only consider the outdoor environment, overlooking indoor thermal comfort and building energy consumption. Therefore, in order to investigate the RHI effect and assess the efficacy of localized heat mitigation measures, this study analyzed 22 types of courtyard layout patterns in a typical centralized village in northern China through detailed field measurements and performance simulations. The results show an obvious heat island effect in the rural centralized residences, where residential zones recorded average temperatures of 1.6 °C higher than those of rural boundaries. Courtyards featuring a south wing significantly alleviated outdoor thermal stress, reducing the discomfort time of extreme Physiological Equivalent Temperature (PET) by 1.5 h compared to those courtyards with a wall. Among the four localized heat mitigation measures examined, the featured black fabric shade performs best for its effectiveness in mitigating outdoor thermal stress, capable of reducing the courtyard's maximum Mean Radiant Temperature (Tmrt) by 21.5 °C and decreasing the duration of extreme PET by 2 h. Photovoltaic modules installed on the roof not only generate energy but also alleviate outdoor thermal stress, reducing the maximum Tmrt by 12.9 °C and lowering 23 % to 28 % daily energy demand, making them highly suitable for deployment in rural areas with high rates of energy poverty. The simulated results indicate that these localized heat mitigation measures mutually reinforce each other in reducing the RHI effect. The combination of four heat mitigation measures can reduce PET by up to 20 % and EUI by up to 44 % compared to the original courtyard. Incorporating these localized strategies into planning practice enables rural planners and policymakers to develop effective interventions against the RHI effect.

http://dx.doi.org/10.1016/j.scs.2024.105782