Downward piston ventilation assisted with a localized - Chair exhaust for mitigation of pathogen transport in educational spaces

This study proposes the integration of a localized - chair exhaust (LCE) device and a downward piston ventilation (DPV) in an educational space. The main aim is to assess the proposed system ability in providing a safe educational space similar to the case implementing the 2 m distancing between students at lower energy consumption. This allows the decrease of the DPV high supply flowrate without jeopardizing the protection level compared to the standalone DPV. A three-dimensional computational fluid dynamics (CFD) model of the educational space with DPV + LCE combination was developed as simulator software. The CFD model was validated experimentally and a parametric study was conducted to determine the best DPV supply airflow rate when assisted with LCE. The DPV flowrate should be capable of (i) preserving high protection levels, (ii) maintaining acceptable thermal comfort levels, while (iii) reducing the energy bill burden. Hence, an infected student was assumed sitting in the middle of the space and the exposure levels of the surrounding students were evaluated using the intake fraction (iF) index. It was found that for a practical use in educational spaces, the DPV system should be operated at 60 l/s per person with LCE at 20 l/s to maintain the high protection potential of the DPV system at 51% energy savings in the overall system energy consumption. Furthermore, the energy performance of the proposed system was compared to that of other ventilation systems implemented in educational spaces while offering same or better protection levels.