Which assumption of the indoor air quality model states that the volume is completely mixed?

The assumption that the volume is completely mixed corresponds to the concept of uniform concentration within the indoor air quality model. This means that, over time, the concentration of pollutants is assumed to be evenly distributed throughout the indoor space. This assumption is critical because it simplifies the modeling of pollutant behavior and allows for easier predictions and assessment of indoor air quality.

The notion of uniform concentration is particularly important in evaluating exposure levels, as it allows engineers and environmental scientists to assume that any point within the space will experience the same concentration of pollutants. This can aid in identifying potential sources of indoor pollutants and in making informed decisions about ventilation, air filtration, and other strategies to improve air quality.

Other assumptions in the model play different roles. For instance, constant volume refers to the maintenance of a fixed volume of indoor air, which is important in understanding how air pollutants accumulate. The constant emission rate assumption pertains to the consistency of pollutant release from sources over time, while equal infiltration and exfiltration rates focus on the balance of air entering and leaving the space, influencing the overall air quality. However, none of these directly indicates the mixing behavior of the air within the space, which is captured by the assumption of uniform concentration.