Future indoor overheating risk for urban village housing in subtropical region of China under long-term changing climate

Over the last two decades, China has witnessed a surge in the emergence of urban villages characterized by high building density and significant migrant populations, primarily due to shifts in land use during urbanization. Housings in urban villages with low-cost design strategies, potentially exposing them to indoor overheating risks under climate changes. Given the scarcity of literature analyzing thermal performance of these houses, this study aims to assess the future indoor overheating risk of common urban village house types based on different construction material in subtropical China with two metrics which are Indoor Overheating Hours (IOH) and Indoor Overheating Degree (IOD), and explore effective methods to counter outdoor thermal stress. A four-month onsite measurement was conducted to calibrate the building thermal environment calculation model. Results demonstrate pronounced indoor overheating risks for both selected houses, Traditional Urban Village House (TUVH) and Contemporary Urban Village House (CUVH), particularly under the Representative Concentration Pathways (RCPs) 8.5 scenario. TUVH and CUVH may experience up to 2111 and 4325 overheating hours, respectively, with the IOD reaching 7.1 degrees C and 10.9 degrees C. Moreover, employing a global sensitivity analysis, we found that adding opaque shading for external wall is an effective retrofit strategy for TUVH and CUVH. This study contributes to evaluating the thermal performance of urban village houses under long-term climate changes with the findings promoting future retrofit strategy research for urban village houses focusing on housing types and usage pattern of the housings.