Gaseous pollutant transmission through windows between vertical floors in a multistory building with natural ventilation

Abstract

a b s t r a c tNatural ventilation is an effective strategy to control thermal comfort in buildings, and can be enhanced depending on the window style. The combination of natural ventilation and window can also facilitate the removal or dilution of gaseous pollutants from indoor sources in newly decorated buildings. However, the windows on the same facade may cause gaseous pollutant cross-transmission during single-sided natural ventilation between households on different floors close to the source. Although some research has focused on the pollutant cross-transmission in buildings, the simplification of windows into rectangular openings often affects accurate knowledge of pollutant transmission characteristics. Therefore, this investigation explored gaseous pollutant cross-transmission through real windows during singlesided, buoyancy-driven ventilation in a multistory building. Six types of windows were modeled for the indoor pollutant of gaseous formaldehyde (HCHO). Computational fluid dynamics (CFD) was utilized to solve characteristics of pollutant transmission inside and outside the multistory building. The results indicated that the ventilation rates, thermal profiles and pollutant transmission inside and outside the building varied for each window type, although the open window areas were identical. The re-entry ratio of exhausted air entering upper floors and the infection risk of epidemic viruses caused by airborne cross-transmission was sensitive to ventilation rates and window configurations, while the sensitivities for window configurations varied case by case. The comparisons also revealed that the specification of ambient temperature and pollutant release rate ultimately did not affect the evaluation of pollutant cross-transmission using CFD.

Numerical investigation of gaseous pollutant cross-transmission for single-sided natural ventilation driven by buoyancy and wind

“…In accordance with guidelines from the American Society of Heating, Refrigerating, and Air-Conditioning Engineers, if the outdoor temperature is 20 � C, the maximum acceptable indoor temperature is 27.5 � C [35]. Hence, an indoor temperature of 28 � C was specified, and the 8 � C temperature difference between the interior and exterior of the building was consistent with our previous study [4].…”

“…A tracer gas representing the gaseous pollutant was released at a constant rate of 20 μg/s. More details regarding the settings are provided in our previous studies [4,29,30].…”

“…Furthermore, the impacts of window configurations on ventilation rates have received considerable attention, whereas studies on pollutant cross-transmission and window configurations remain somewhat limited. Extending our previous study [4], the work herein investigates gaseous pollutant cross-transmission due to buoyancy and wind for single-sided natural ventilation. The impacts of ambient wind, window configuration, and source location on pollutant cross-transmission are discussed, and new insights into cross-transmission are provided.…”

“…Natural ventilation is generally considered to be an effective solution for reducing indoor pollutants but must be carefully examined to determine its effectiveness. For example, natural ventilation may cause pollutant transmission between multistory households [3], which can be adversely affected if they are adjacent to households with high levels of indoor pollutants [4]. Moreover, the airborne transmission may contribute to the spread of infectious diseases, as demonstrated during the worldwide outbreak of severe acute respiratory syndrome (SARS) in 2003 [5][6][7].…”

“…The driving forces, as well as window and door configurations, that altered the ventilation rates can impact pollutant cross-transmission. It has been shown that some openings serve as a barrier (e.g., a partially opened tilt window) and effectively restrict pollutant transmission between floors, even under active ventilation conditions [4]. Gao and Lee [24] applied full-scale experiments to identify the ventilation performance of three window types and found that the performances varied based on the window types and locations.…”