Heat Risk Assessment and Renewal Protection Strategies for Traditional Street-facing Dwellings with Eaves Gallery under Extreme Heatwave Events:A Case Study based on Xiaohe Town,Xiaochang

YAN Shuting; FANG Zehua; ZHOU Xilin

doi:10.3969/j.issn.1000-0232.2026.01.011

Abstract：Extreme heatwave events intensified in frequency and magnitude across the Yangtze River Basin in the context of global warming.This shift poses a critical threat to the thermal stability of traditional vernacular dwellings and the physiological well-being of their occupants.The Street-facing Dwelling with Eaves Galleries(SDEG)presents as a typical climate-responsive typology within China's Hot-Summer and Cold-Winter(HSCW)zone.Characterized by a"shop-front,residence-rear"configuration,this typology leverages transitional buffer zones,including colonnades and internal courtyards,to modulate the microclimate between the street and the interior.Despite these inherent bioclimatic features,the adaptive resilience of SDEGs under contemporary extreme thermal stress remains insufficiently quantified.Currently,there is a significant lack of empirical evidence and scientific grounding to inform the climate-conscious refurbishment,conservation and preservation of these structures. This study aims to address this gap by evaluating the heat-mitigation mechanisms of the SDEG typology,providing a robust framework for its protection in an era of climatic instability.Taking Xiaohe Town of Xiaochang in Hubei Province as an example,the characteristics of the thermal environment and heat risks for SDEGs during extreme heatwaves were systematically revealed.Based on the field measurements,the cooling effects of various refurbishment strategies through Computational Fluid Dynamics(CFD)simulations,providing a quantitative basis for the climate-responsive renewal of traditional SDEGs in commercial districts.During the extreme heat period from August 17 to 18,2022,three representative street houses and street monitoring points were selected,with 13 measurement points installed to continuously monitor air temperature,relative humidity,wind speed,and other parameters.A microclimate model was established and validated using the RNG k-ε turbulence model,demonstrating high fidelity with coefficients of determination(R2)for temperature,wind speed,and humidity of 0.82,0.86,and 0.89,respectively,and Root Mean Square Errors(RMSE)of 1.1℃,0.025 m/s,and 3.6％.Quantified heat risk assessments reveal that while maximum thermal stress in indoor shops reached Class Ⅳ(30℃<WBGT<33℃),semi-outdoor and outdoor spaces exhibited more critical Class V(WBGT>33℃),with east-west oriented dwellings notably impacted by late-afternoon solar radiation. Based on the analysis of the thermal environment and heat risk,three refurbishment and conservation strategies were proposed and simulated:1)replacing modern granite paving with traditional cobblestone paving;2)installing an intelligent sensor-based shading system at the eaves;3)adding a double-layer ventilated ceiling below the first-floor slab.Simulation results showed that strategy 1 reduced the wet-bulb globe temperature(WBGT)by 1.19 ℃ at noon;strategy 2 reduced the maximum indoor WBGT by 0.52℃;and strategy 3 reduced the maximum indoor WBGT by 0.45℃.However,strategy 3 may lead to localized temperature increases during periods of small diurnal temperature variation,thus requiring optimization of shading and courtyard layouts.The findings suggest that the colonnade,as a transitional space,plays a significant role in thermal buffering,but in east-west oriented buildings,indoor commercial spaces still accumulate high heat risks during the afternoon.The combination of CFD simulations with fine grids and detailed material data meets the accuracy requirements for simulating the thermal environment of traditional street houses.Refurbishment measures such as paving material replacement,the addition of intelligent shading systems,and the installation of double-layer ventilated ceilings significantly improve the thermal environment during the midday period.This research provides a quantitative basis and strategic support for the climate-responsive renewal and protection of SDEGs in commercial districts.