Indoor Thermal Environment And Human Thermal Response Based On The Influence Of Solar Radiation

With the improvement of people’s living standards,indoor thermal environment and human thermal comfort have became a focued point concerned by society.At present,the international codes and standards,such as ASHRAE Standard 55-2014 and ISO7730,are proposed on the basis of the uniform and stable indoor environment.Many results indicated that there is a big deviation between the predicted models and the actual thermal response of the human body in the un-uniform environment.At present,there are many kinds of buildings with glass curtain wall,transparent roof and so on.As a result,more solar radiation enters the room.High-intensity solar radiation aggravates the formation of the un-uniform indoor thermal environment.Previous studies on un-uniform thermal environment mostly focus on floor air supply,air conditioning,asymmetrical long-wave radiation caused by cold/hot radiation plate,etc.Solar radiation belongs to short-wave radiation.On the one hand,it acts on the environment,changes the indoor radiation field and the average radiation temperature,and then affects the thermal balance between the human body and the surrounding environment.On the other hand,when the sunlight directly act on the human body,it changes the skin temperature of the human body,and its effect on the human body thermal sensation is direct and rapid.When different parts of the human body are exposed to the non-uniform temperature field,the local thermal sensation of the body changes with the increase of the body area of direct sunlight.Indoor thermal comfort under the influence of solar radiation has its own particularity,and there is little research on this aspect at present.In this paper,the basic characteristics of solar radiation are analyzed.It is pointed out that the influence of solar direct radiation and scattering components should be taken into account in the mean radiation temperature.Ecotect can used to simulate the sunshine trajectory of a typical building.The indoor thermal comfort field test under the influence of solar radiation is designed.The indoor thermal environment characteristics under this condition are analyzed by using the field measurement and CFD simulation methods.Four different working conditions are designed to test the effects that direct sunlight on different parts of the body,and test the skin temperature,local thermal sensation,local thermal comfort and thermal acceptability of forehead,chest,back,hands,right and left thighs,right and left upper arms respectively.The results show that the indoor wall temperature,space temperature and mean radiation temperature are closely related to the solar radiation intensity,and the indoor thermal environment reveals the phenomenon of non-uniform distribution.The calculation method of the average radiation temperature just considering the wall long wave radiation cannot accurately evaluate the indoor thermal environment,so the influence of solar radiation on the average radiation temperature should be considered in the calculation process.For the uniform environment under non-radiation conditions,there is little difference in skin temperature between different parts of the human body.When the human body is affected by solar radiation,the difference in skin temperature between different parts is obvious,and with the increase of direct solar radiation,the difference will become larger and larger.During the experiment,infrared thermal imager was used to verify this phenomenon.Similar to the law of skin temperature,local thermal sensation and local thermal comfort also have the same change rule.The design of building air conditioning usually considers the division of the inner and outer areas of the plane due to the load demand of different areas in the interior caused by the fluctuation of outdoor meteorological parameters.The results of this research suggests that the division of room air conditioning radiation area and non-radiation area should be fully considered on the basis of traditional building partition,in order to achieve human body thermal comfort and reduce energy consumption of air conditioning system.