California Institute for Energy and Environment (CIEE)

Many modern low-energy ventilation schemes, such as displacement or natural ventilation, require the use of temperature stratification in a space. The ability to extract air at elevated temperatures is necessary for energy-efficiency and free cooling. The adoption of these energy-efficient ventilation systems still requires that they provide an acceptable level of indoor air quality and comfort. It is widely believed, although not comprehensively studied and validated, that such low energy ventilation systems will be more effective at removing contaminants. In this work, the focus is on the transport of passive and particulate contaminants in a displacement-ventilated space. By representing heat sources as ideal sources of buoyancy,simple analytical models have been developed that allow us to compare the average efficiency of contaminant removal between traditional and modern low-energy systems. These models are then extended and solved numerically to study and compare the spatial distribution of contaminants within the space of interest. In order to validate the models, small and large scale laboratory experiments were conducted. The results of the models and the experiments are ultimately extended to understand the fate of particulate contaminants, which suffer the additional effect of gravitational settling.