Different Thermal Mitigation Strategies In University Campus Outdoor Spaces

The outdoor open space of university campus is the main place for teachers and students to study,live,exchange activities,and entertainment.Its thermal comfort will directly affect students’outdoor activity level and learning quality.High temperature in summer seriously affects people’s health and outdoor thermal comfort.In view of the main meteorological indicators affecting human thermal comfort in summer,such as air temperature（T_a）,global radiation（G）and relative humidity（RH）.Shade,mist spraying and shade+mist were selected for the study.By means of meteorological parameter measurement,questionnaire survey and skin temperature measurement,the effectiveness of Different heat relief strategies on improving outdoor thermal environment,improving human thermal comfort and alleviating physiological reaction were evaluated.Universal Thermal Climate Index（UTCI）was selected as the thermal index and skin temperature as the physiological evaluation index.Finally,based on the influence of three heat mitigation strategies on thermal environment,human thermal perception and thermal comfort as well as physiological perception,relevant suggestions and measures were proposed to improve human thermal comfort by using shading and spray heat mitigation strategies.Combined with space landscape elements,landscape optimization and enhancement strategies for outdoor open space on campus were formed based on improving summer microclimate.The results showed that:1)Mist spraying and shade were effective in improving respondents’outdoor thermal comfort.The cooling effect of mist spraying was more effective than shade,while shade+mist provided a wider thermal comfort range.2)UTCI declined among cooling strategies by 12.31℃（shade+mist）,8.03℃（mist spraying）and3.48℃（shade）on average.3)Shade and mist caused similar cooling effects on skin temperature（ST）,but MST plateaued 5 min after exposure to these cooling environments in isolation.Shade+mist provided the greatest cooling effect with MST continuing to drop as the exposure continued.4)Predictive models showed that MST in shade,mist spraying and shade+mist decreased 0.24℃,0.21℃and 0.16℃,respectively when T_adeclined 1℃with constant RH and mean radiation temperature(T_mrt).MST in shade,mist spraying and shade+mist decreased 0.05℃,0.08℃and 0.06℃,respectively where RH increased 1%with constant T_aand T_mrt.The results of this study provide relevant suggestions and strategies for shading and spraying strategies to improve human thermal comfort in campus open space,and provide reference for outdoor thermal comfort design of campus in summer.