| With the rapid economic growth of our country and the continuous increase of the urbanization rate,each city needs more space for development.Therefore,the development of urban underground space is an inevitable choice in the process of urbanization.There is a difference of spatial structure and indoor heat gain between underground and above-ground space.It is necessary to study the thermal characteristics of underground space and the influence of human thermal comfort to provide a scientific basis for the rational construction of a healthful and comfortable underground space environment.First of all,this paper theoretically analyzed the environmental parameters which affect the heat gain of underground space,and used DEST software combined with the ground temperature calculation model to simulate the thermal environment of underground and above-ground office rooms in Chongqing.According to the difference of indoor air temperature and the mean radiative temperature,between the underground and above-ground rooms,the ratio between convective and radiative heat exchange of human body was introduced based on the Fanger’s thermal comfort equation.And the influence of the indoor air and the mean radiative temperature difference on the thermal comfort of the human body was analyzed.Then,a field experiment of was conducted in underground and above-ground public space in Chongqing area,and the experimental data was analyzed to verify the accurateness of the simulation calculation results.According to the thermal comfort level,the recommended ranges of indoor air temperature in Chongqing underground space were given: summer(25.2~28.1℃),transition season(17.8~26.1℃),Winter(13.6~19.6℃).For air design temperatures in underground space in Chongqing,it is generally effective to use design values from existing specifications.Finally,using DEST software and the basic ground temperature model,the thermal environments in underground spaces,of typical cities in different regions of China,were simulated and calculated.Based on the indoor air temperature and mean radiative temperature of underground space in different regions,the convective and radiative heat loss of the human body were calculated.And the regional differences in the effect of space thermal environment on human thermal comfort were analyzed.Considering factors such as outdoor climate and human adaptability in different regions,the recommended indoor air design temperatures,for different seasons in typical cities,were given: Harbin(Winter: 10~16℃;Summer: 23~27℃),Beijing(Winter: 14~19℃;Summer: 24~27℃),Nanjing(Winter: 15~20°C;Summer: 25~28 ℃,Guangzhou(Winter: 18~22 ℃;Summer: 26~28℃).For heating and cooling seasons,comparing recommend value to the specified value: In heating winter,up to 5 to 10% of energy can be saved under the level I thermal comfort,and up to 20 to 40% of energy can be saved under the level II thermal comfort.This article explains the main reason why the thermal comfort of underground space is higher: Due to the different thermal environment characteristics,the heat dissipation ratio of human body in the underground space is significantly different from that in the aboveground.If using the same environmental control methods,the human body has a higher heat dissipation stability in underground space,and has a stronger thermal physiological adjustable ability to resist the environmental temperature disturbance.In addition,through the study of the thermal environment of underground spaces in typical cities,ventilation and air-conditioning strategies in different regions were obtained: In the areas with a ground temperature greater than 15℃: cooling is required in summer and ventilation is required in winter;in areas with a ground temperature less than 15℃,heating is required in winter and ventilation is required in summer.The recommended range of indoor air temperature in different regions in this paper can provide reference for the design of thermal environment in underground space. |
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