Optimum Design Of Residential Open Spaces For Improving Outdoor Thermal Comfort

Thermally comfortable residential open spaces could enable more activities and contribute to the livability of sustainable cities.The microclimate and outdoor activities in five typical residential open spaces in Xi'an in winter,spring and summer were investigated using physical measurements,questionnaires and activity records and the relationship among microclimate,thermal sensation and human behavior in a cold region of China was identified.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.Optimum design strategies for open spaces and design suggestions for residential areas in Xi'an were proposed based on the findings of outdoor thermal comfort.Results demonstrated that: 1)Except for air temperature and relative humidity,wind speed,solar radiation,globe temperature,mean radiant temperature and PET differed significantly among spaces.2)Solar radiation and wind were the main meteorological factors affecting thermal sensation and activities in winter,and solar radiation in summer had a strong influence on thermal sensation and outdoor activities.Thermal comfort was not only affected by thermal sensation,but also by thermal adaption.3)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.4)Residents can better endure “cold stress” in winter than “hot stress” in summer when conducting specific activities(such as playing and looking after children).5)Thermal adaption was affected by factors such as gender and culture.Occupants in cold regions tended to improve thermal comfort in winter and summer by seeking sunlit and tree shaded areas,respectively.6)The neutral PET,neutral PET range and acceptable PET range in Xi'an were identified as 19.7?,12.4–26.9? and 9.8–30.7?,respectively.PET calibration of thermal sensation vote(TSV)in Xi'an was very hot(> 53.6?),hot(48.2-53.6?),warm(41.3-48.2?),slightly warm(30.7-41.3?),neutral(9.8-30.7?),slightly cool(-0.8-9.8?),cool(-7.6 to-0.8?),cold(-13.1 to-7.6?)and very cold(<-13.1?).Adaptation to the Predicted Percentage of Dissatisfied(PPD)relation for Xi'an was also adjusted.7)Optimum design strategies for open spaces were proposed within implement of shelterbelts,shaded facilities and deciduous trees.8)Planning and design for residential community should aim at creating comfort outdoor environment to meet thermal adaptation needs of residents by properly planning the layout of outdoor spaces and creating a variety of open spaces.Urban designers should use appropriate thermal benchmarks in design to create thermally comfortable environments in public open spaces during critical periods by synthesizing building layout,green space,shade and ventilation.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.