Outdoor thermal benchmarks and their application to climate‒responsive designs of residential open spaces in a cold region of China

Abstract This study aims to identify the relationship among microclimate, thermal sensation and human behavior in a residential community in a cold region of China. Five typical residential open spaces in Xi'an, China were investigated using physical measurements, questionnaires and activity records to determine how thermal comfort relates to outdoor activities. Physiological Equivalent Temperature (PET) was applied to quantitatively determine the outdoor thermal benchmarks in Xi'an, and variation in thermal benchmarks was compared with other climatic zones. Finally, a ‘research for design’ approach for climate‒responsiveness of residential open spaces was proposed based on thermal benchmarks. Results demonstrated that: 1) Except for air temperature and relative humidity, wind speed, solar radiation, globe temperature, mean radiative temperature and PET differed significantly among spaces. 2) Residents preferred activities in sunlit spaces in winter, tended to prefer activities in shaded spaces in summer, but activity time and space selections were inconspicuous in spring. 3) Residents can better endure “cold stress” in winter than “hot stress” in summer when conducting specific activities. 4) The neutral PET, neutral PET range and acceptable PET range were identified as 19.7 °C, 12.4–26.9 °C and 9.8–30.7 °C, respectively; adaptation to the Predicted Percentage of Dissatisfied (PPD) relation for Xi'an was also adjusted. 5) Optimum design strategies for open spaces were proposed within implement of shelterbelts, shaded facilities and deciduous trees. These results should help urban designers better understand residents' thermal comfort and adaptive behaviors and provide design guidelines for residential open space in China's cold region.