| With the development of economy,modern people have more and more demands for the quality of life,and the demand for indoor air quality also increases correspondingly.Eighty percent of people’s life is spent in indoor environment.If a good indoor environment is not provided,at least the quality of people’s work and study will be reduced,and at worst,people will suffer from more serious sick building syndrome(SBS).Many scholars have conducted long-term tests on air quality of bedrooms and office buildings.They find that a large proportion of rooms appear to be poorly ventilated,resulting in excessive levels of carbon dioxide.When studying the influence of indoor carbon dioxide concentration on people,scholars partly consider the influence of special environment(ultra-high carbon dioxide concentration in submarines,underground,dry ice workshop and so on),and some scholars only study the influence of indoor carbon dioxide on people without considering the interaction between temperature,humidity and carbon dioxide concentration.Only a few scholars have taken the interaction between temperature and carbon dioxide concentration into account,but no more regular results have been obtained.In order to further clarify the integrated effect of carbon dioxide,temperature and humidity,this study sets different indoor environmental working conditions by changing indoor carbon dioxide concentration,temperature and humidity,and studies the interaction of temperature,humidity and carbon dioxide on the impact of human law,so as to determine different environmental conditions of carbon dioxide concentration limit.In this paper,a climate chamber with independent control of temperature,humidity and carbon dioxide concentration was established.Based on the experiment,the influence of carbon dioxide concentration on human and the interaction between temperature,humidity and carbon dioxide concentration were studied.A total of 30 operating conditions were set in the experiment,with three temperature settings: 23℃,26℃,and 28℃,three humidity settings:40%,55%,and 75%,and four carbon dioxide concentration settings: 700 ppm,1000 ppm,1200 ppm,and 2000 ppm.The subjects were postgraduate students aged 23-26 and in good health.A total of 195 person-time were conducted.The cognitive ability,SBS symptoms and physiological parameters of the subjects were monitored by cancellation test,subjective questionnaire survey and heart rate monitoring equipment.The analysis of variance was used to analyze the significance of influence factors.The main results are as follows:(1)In the SBS symptom survey,with the increase of carbon dioxide concentration,temperature and humidity,subjects will have more and more types of SBS symptoms and the symptoms will become more and more serious.High temperature and high carbon dioxide concentration of the environment are easy to produce serious symptoms like headaches,dizziness,and nausea.However,the high humidity environment is the most likely to cause severe symptoms of stuffiness.In the high humidity environment,even if the carbon dioxide concentration is maintained at a low level,the subjects will also show relatively serious symptoms of SBS.(2)In the indoor environmental operating conditions of 23-26℃,45-75% relative humidity and 700-2000 ppm carbon dioxide concentration,no obvious regular changes of heart rate are found in the subjects under certain operating conditions,that is,there is no significant change of heart rate in the range of temperature,humidity and carbon dioxide concentration.(3)In the absence of temperature and humidity,the concentration of carbon dioxide over1000 ppm will have adverse effects on people’s cognitive ability,and the higher the concentration of carbon dioxide,the more serious the adverse effects.When temperature and carbon dioxide concentration interact together,at 23℃,even a carbon dioxide concentration of2000 ppm only has a slight impact on human cognitive ability.While at 28℃,a carbon dioxide concentration of 1000 ppm will have a negative impact on human cognitive ability.The interaction between temperature and carbon dioxide concentration shows that lower temperature can weaken the effect of higher carbon dioxide concentration on people’s cognitive ability,while higher temperature can aggravate the effect of carbon dioxide on people’s cognitive ability.The effect of humidity on people’s cognitive ability is not significant,that is,humidity level do not affect people’s cognitive ability.(4)It is suggested that the limit of indoor carbon dioxide concentration should be raised to2000 ppm when the air conditioning temperature is set at or below 23℃.When the air conditioning temperature is set at 23-26℃,the indoor carbon dioxide concentration limit is set at 1200 ppm.When the air conditioning temperature is set at 26-28℃or higher,the indoor carbon dioxide concentration limit is set below 1000 ppm.At the same time to ensure that the humidity control at 40-50%. |
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