Ventilation mode performance against airborne respiratory infections in small office spaces: limits and rational improvements for Covid-19

The Coronavirus disease (Covid-19), caused by the SARS-CoV-2 virus, has produced significant social and economic disruptions in different countries. Current evidence suggests a strong correlation between the infection and the cohabitation of indoor spaces. International organizations and experts consider that the airborne transmission through aerosols can occur in specific conditions and that inadequate ventilation increases the risk of infection. As a result, the increase in ventilation rates and air filtration efficiencies are recommended for public buildings in the context of Covid-19, with significant impacts on energy consumption, and a paradigm shift in the design of ventilation systems is necessary for this new context. Therefore, this study has assessed the comparative performance of the displacement ventilation and the mixed ventilation mode on reducing the risk of long-range airborne infection for the Covid-19 in a small office application. A coupled multizone-CFD (Computational Fluid Dynamics) software developed by the National Institute of Standards and Technology was used in this study to assess the relative performance of several design solutions related to different ventilation modes, filter efficiencies, and outdoor air flow rates. The results demonstrate that the displacement ventilation technique produces a better overall performance in reducing the SARS-CoV-2 airborne infection risk than the conventional mixed ventilation for all the studied cases.