The Indoor Air Quality Evaluation And Numerical Simulation Of The Underground Supermarket

The field investigation of several public buildings in seven cities across the country were conducted during the project period of National Science and Technology Support Program "Building a healthy indoor environmental control and improvement of key technology research and demonstration"(2012BAJ02B06).It found that the indoor air quality of underground mall in Chongqing was not going well. The results of both objective testing and subjective questionnaire survey showed that the indoor air quality underground were worse than the above-ground building. Based on the above problems, the comprehensive and systematic research of a selected underground supermarket are conducted.Real-time monitoring for a whole day of indoor environmental parameters, including temperature, relative humidity, wind speed, formaldehyde, carbon dioxide, TVOC, and PM2.5 and subjective questionnaire survey are conducted at the same time during winter, summer and transition season condition. Present indoor air quality status is obtained through statistical analysis of testing results. Based on grey theory systemand using grey correlation analysis method, the main influencing factors on subjective feelings and health of occupants are researched. And then, present indoor air quality status is researched through evaluation of indoor air quality in each division of the selected underground supermarket. Based on the research findings above, numerical simulation of indoor air quality is carried out using FLUENT software. The best control strategy of indoor air quality is obtained with optimized simulation parameters. Finally, threemeasures for the improvement of indoor air quality in underground supermarket.In this paper, several achievements have been obtained as follows:(1) The analysis of field test resultshow that: though with a low wind speed, the thermal and humid environment meet the comfort requirement; the concentrations of pollutants indoors remain high, particularly TVOC and CO2,100%, 71.3%, and 21.8 % of all the air samples derespectively exceeded the Chinese national indoor air quality standard for TVOC, CO2 and formaldehy.With no significant variation rule, the concentration of PM2.5 remain ata low level. At weekends / working days, different functional areas, different seasons, the concentration levels are different. Indoor occupants think poorly of indoor environment as a whole. The dissatisfactory rate of staff in supermarket toward indoor air quality is higher. The main symptoms of indoor occupants are fatigue, nausea and poor breathing. Overall staff’s subjective evaluation of indoor air quality is not good.(2) CO2 and TVOC are the main influencing factors of the adverse health symptoms of indoor occupants. The indoor air quality of the whole supermarket is at the light pollution level. The air quality inside the supermarket is worse than that outside.(3) With pre-ventilation strategy, namely 10 minutes before the supermarket open for business with a ventilation frequency of 10 time/h, theTVOC concentration indoors goes down from 2.0mg/m3 to 0.49 mg/m3. In the premise of guaranteeing the comfort of indoor occupants, toincrease air output on the area that with large amount of pollutants can significantly reduce the concentration of pollutants and contaminants partition grave phenomenon. What’s more, making full use of storage cabinets and other cold sources can reduce the overall average temperatureto a certain extent.(4) Finally, according to the problems and characteristics of indoor air qualityof underground supermarket, some improvement measures about the indoor air quality are proposed.