Field Evaluation of a Displacement Ventilation System for a Cold Climate School
Date
2013-11-29
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Abstract
Displacement ventilation (DV) is believed to provide better indoor air quality for a given outdoor air flow rate. Few reports of field assessments of DV have been published, especially for cold climates. A post-occupancy study of DV performance was conducted at Lawrence Grassi Middle School (LGMS), located within Alberta’s cold-dry climate. The DV performance evaluation addressed vertical temperature profile, ventilation effectiveness (VE), and thermal comfort in five spaces (three classrooms, the computer lab, and the library) during three different seasons. This study included testing of parameters that may affect DV performance such as: door position, season, occupancy density, thermal loads, ventilation rate, and radiant surfaces temperature.
Field evaluation suggested that DV could provide improved thermal comfort and VE compared to conventional (i.e., mixing ventilation) systems when operated as prescribed in the literature. At LGMS, performance indices clearly showed that DV in classrooms was functioning as one would expect. The library had a clear short-circuit due to high supply air discharge temperature and a reversed temperature profile. The computer lab showed similarity to typical DV performance, with lower VE and cooler thermal environment than the classrooms.
Thermal comfort indices reflected an overall thermal environment that was cooler than neutral, especially near the floor. This was largely due to a radiant slab colder than comfort limits. Thermal comfort indices leaned toward the cooler edge of comfort limits. Comparing spaces, the classrooms had the best comfort levels, followed by the computer lab and then the library.
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Citation
Sabbagh, M. J. (2013). Field Evaluation of a Displacement Ventilation System for a Cold Climate School (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca. doi:10.11575/PRISM/26175