Study On Indoor Air Quality In Passive Solar Houses

Passive heating and cooling technology is an old and traditional regulation method. In recent years, with the in-depth research of the WSAC (Wall mounted Solar Air collector), the effect of this heating method on indoor air quality attracts more and more people's attention, especially in the following areas: hot air circulation may be lead to 1) human health and comfort problems due to the change of room relative humidity; 2) the potential healthy problems caused by indoor reentrainment of dust; as well as 3) the effect of high temperature air circulation improves indoor health level. But there are few studies on indoor air quality of this special construction, and it is incompatible with rapid development of passive solar air heating and cooling technology. Based on this background, field surveys of indoor temperature and humidity changes, concentration of inhalable particles, and bacterial counts of a test room with WSAC and a passive solar school were conducted. The indoor environment of the objects is under the action of solar air heating system which based on principle of Trombe wall. The characteristics of indoor air flow field at different speeds have been analyzed using numerical simulation method, and the relevance of it and the migration characteristics of inhalable particles have been discussed. The main research topics and results in this thesis are summarized as follows:Based on the research background review and the discussion of the relevant basic knowledge in chapter 1 and 2, chapter 3 focuses on the investigation results of air tightness, air change rate and indoor air environment of the new residential buildings, which built in nearly decade, in the city of Dalian. The result shows that the indoor air quality and air tightness performance of residences is good during heating period. But the air change rate can not satisfy the design requirements of 0.5 times/h. In addition, in chapter 3, the test results of the impact on indoor air quality using ventilators installed on the windows have been discussed. Natural ventilation rate and indoor and outdoor air temperature difference play a decisive role on ventilation performance. Under the same experimental conditions, indoor concentration of formaldehyde will be decreased 30% with natural ventilation rate increased 2.1 times.Chapter 4 mainly discusses the field survey results of indoor environment in the test room with WSAC and a passive solar elementary school, which heating with collector-storage wall (embedded WSAC). Based on the test results of temperature, humidity, bacterial counts, concentration of inhalable particles and other parameters, the mainly conclusions are: 1) heating using WSAC can not only improve the room temperature effectively, but also reduce the bacterial counts after the air flowing through WSAC, which indicates the internal high-temperature environment can suppress microbial survival; 2) In WSAC, because the ascending velocity of air flow is much higher than the self-velocity of particles, the particles which enter the WSAC will be back to the room with the air flow once more. When the air supply velocity is higher than 0.2m/s, dust depositing in the air duct is also easily bowed into the room. Under the mechanical ventilation conditions, air door and fan play a certain role in disturbances for the concentration of inhalable particles near the vent. When air door or fan changes its current situation, the standard deviation of the concentration at the measuring point is 2 to 3 times to former and later relatively stable state respectively.The indoor flow field characteristics at different speeds in houses with WSAC have been analyses using numerical simulation method, in chapter 5. According to the simulation results, when the air supply velocity from 1.5m/s change to 3.5m/s, wind speed is gradually larger in work area, but the wind speed near-floor is less than 0.2m/s, reentrainment of dust will not be caused.