Airflow and Pressure Design Review of Modular Negative Pressure Wards

Abstract

In the aftermath of the COVID-19 pandemic, the urgent need for the rapid deployment of healthcare facilities propelled the rise of modular construction using an infill approach. In these modular, negative-pressure wards, the design of indoor airflow and pressure plays a crucial role in meeting the ventilation strategies required for isolation facilities. Accordingly, this paper focuses on modular negative-pressure wards employing an infill construction method and proposes an appropriate spatial pressure distribution to address the problem of air tightness degradation due to leakage. This study analyzed the indoor airflow and pressure distribution of a unit module corresponding to an infill. It aimed to examine whether the pressure difference with the adjacent room is maintained and to assess its effectiveness in isolating contaminated air. First, the airflow rate of the heating, ventilation, and air conditioning system in the unit module was calculated to ensure that it would meet the performance criteria of the negative-pressure ward. Afterward, based on the calculated rate, the study assessed the airflow and room-specific pressure within a typical floor, encompassing both the unit module and associated nursing support facilities. Here, the airflow in the external corridor of the typical floor was divided into two cases according to the pressure distribution: negative pressure and atmospheric pressure. The calculation results were compared using a computational fluid dynamics tool. The analysis results confirm that the air isolation performance is adequate as the pressure difference between adjacent rooms in the unit module and the typical floor was maintained at 2.5 Pa. Additionally, the indoor airflow in the negative-pressure isolation room formed a stable flow at a slow speed of 0.1–0.2 m/s, minimizing the possibility of air contamination from outside the isolation room. In particular, Case B of the typical floor design proposes a method to optimize the pressure distribution in the modular negative-pressure ward by designing the ventilation flow rate at atmospheric pressure level. Thus, this study emphasizes that atmospheric pressure design is appropriate when designing pressure in areas where negative-pressure control is difficult and can contribute to the design and improvement of similar medical facilities in the future.