Wallace L A, Emmerich S J, Howard-Reed C
US EPA, 12201 Sunrise Valley Drive, 555 National Center, Reston, Virginia 20192, USA.
J Expo Anal Environ Epidemiol. 2002 Jul;12(4):296-306. doi: 10.1038/sj.jea.7500229.
A year-long investigation of air change rates in an occupied house was undertaken to establish the effects of temperature, wind velocity, use of exhaust fans, and window-opening behavior. Air change rates were calculated by periodically injecting a tracer gas (SF(6)) into the return air duct and measuring the concentration in 10 indoor locations sequentially every minute by a gas chromatograph equipped with an electron capture detector. Temperatures were also measured outdoors and in the 10 indoor locations. Relative humidity (RH) was measured outdoors and in five indoor locations every 5 min. Wind speed and direction in the horizontal plane were measured using a portable meteorological station mounted on the rooftop. Use of the thermostat-controlled attic fan was recorded automatically. Indoor temperatures increased from 21 degrees C in winter to 27 degrees C in summer. Indoor RH increased from 20% to 70% in the same time period. Windows were open only a few percent of the time in winter but more than half the time in summer. About 4600 hour-long average air change rates were calculated from the measured tracer gas decay rates. The mean (SD) rate was 0.65 (0.56) h(-1). Tracer gas decay rates in different rooms were very similar, ranging only from 0.62 to 0.67 h(-1), suggesting that conditions were well mixed throughout the year. The strongest influence on air change rates was opening windows, which could increase the rate to as much as 2 h(-1) for extended periods, and up to 3 h(-1) for short periods of a few hours. The use of the attic fan also increased air change rates by amounts up to 1 h(-1). Use of the furnace fan had no effect on air change rates. Although a clear effect of indoor-outdoor temperature difference could be discerned, its magnitude was relatively small, with a very large temperature difference of 30 degrees C (54 degrees F) accounting for an increase in the air change rate of about 0.6 h(-1). Wind speed and direction were found to have very little influence on air change rates at this house.
对一所有人居住房屋的换气率进行了为期一年的调查，以确定温度、风速、排气扇的使用和开窗行为的影响。通过定期向回风管道注入示踪气体（SF₆），并使用配备电子捕获检测器的气相色谱仪每分钟依次测量10个室内位置的浓度来计算换气率。还测量了室外和10个室内位置的温度。每5分钟测量一次室外和5个室内位置的相对湿度（RH）。使用安装在屋顶的便携式气象站测量水平面上的风速和风向。自动记录恒温控制阁楼风扇的使用情况。室内温度从冬季的21摄氏度升至夏季的27摄氏度。同期室内RH从20%升至70%。冬季窗户仅在少数时间打开，但夏季超过一半时间打开。根据测得的示踪气体衰减率计算出约4600个小时平均换气率。平均（标准差）率为0.65（0.56）h⁻¹。不同房间的示踪气体衰减率非常相似，仅在0.62至0.67 h⁻¹之间，表明全年条件良好混合。对换气率影响最大的是开窗，长时间可将换气率提高至2 h⁻¹，短时间（几小时）内可提高至3 h⁻¹。阁楼风扇的使用也使换气率提高了1 h⁻¹。使用炉扇对换气率没有影响。尽管可以看出室内外温差有明显影响，但其幅度相对较小，30摄氏度（54华氏度）的非常大的温差导致换气率增加约0.6 h⁻¹。发现风速和风向对这所房屋的换气率影响很小。
