Planning and Design of a Full-Outer-Air-Intake Natural Air-Conditioning System for Medical Negative Pressure Isolation Wards

Abstract

In the beginning of 2020, the coronavirus (COVID-19) pandemic started to spread globally, causing panic to the lives of people around the world; many countries executed lockdown of cities or even total lockdown of the entire countries. The coronavirus disease (COVID-19) is transmitted via air droplets. In medical environments that use traditional hermetic ventilation systems, medical personnel who come in contact with patients are more susceptible to infection compared to regular staff; therefore, the air flow and air quality of hermetic negative pressure isolation wards are highly critical. For this purpose, the study proposes a full-outer-air-intake natural air-conditioning system for negative pressure isolation wards. This innovative system draws in large amounts of fresh external air to greatly improve the air exchange rate in wards; negative pressure environments can be implemented depending on requirements to solve the issue of nosocomial infections in traditional negative pressure isolation wards that draw air from within the hospital. This greatly reduces the probability of nosocomial infection and infection via air droplets; furthermore, the system’s intake and exhaust paths are completely isolated, solving the issue of air cross-contamination. Based on the results from the experiment site, this innovative system was designed and implemented based on the guidelines of hospital facilities and achieved air exchange per hour in excess of 12 times/hour, reaching a maximum of 54.5 times/hour. Indoor CO2 concentration was 576 ppm, negative pressure was −14 Pa, indoor temperature was 23.3°C, indoor humidity was 54.1%, and sensible heat exchange efficiency (ηs) was 105.88% which effectively reduced ventilation load. Therefore, this innovative full-outer-air-intake natural air-conditioning system can provide medical staff and patients with a safe and healthy environment that prevents cross-infection.

Experimental studies on airborne transmission in hospitals: A systematic review

“…Amongst them, 17 explored the use of alternative ventilation systems or modes (e.g. mixing ventilation, displacement ventilation and natural ventilation), [63][64][65][66][67][68] configurations (e.g. air change rates, pressure differentials and exhaust-return locations), [69][70][71][72][73][74][75][76] system operational controls 77,78 and system filtering units 79 in reducing the exposure to airborne particles and contaminants and the infection risk of airborne diseases.…”

“…Besides bioaerosol concentrations, environmental conditions such as ACH, air velocity and particle levels are often measured to assess the influences of experimental scenarios. 68,71,77,79,85 Many factors that were considered in the experiment can influence environmental conditions. Therefore, it is necessary to conduct repeated experiments to ensure the validity of the results.…”

Simulation Study on Airflow Organization and Environment in Reconstructed Fangcang Shelter Hospital Based on CFD

“…Due to the use of all fresh air systems and the requirement of stable negative pressure in the indoor environment, ref. [45] shows that the negative pressure can be formed when the inlet air volume of the better-sealed large-space building is 60~90% of the exhaust air volume. Therefore, the inlet air volume is 80% of the exhaust air volume, and the inlet air volume is 36,000 m 3 /h.…”

The role of the built environment in updating design requirements in the post-pandemic scenario: a case study of selected diagnostic facilities in Brazil

“…The selected papers were dedicated mainly to exploratory assessments (14; 35%), literature reviews (12; 30%) and experimental studies (10; 25%). Figure 3 shows that China housed the more significant number of screened studies (6; 21%) (Liu et al, 2020;Wang, 2021;Wang, Qiao, Zhou, & Yuan, 2020;Weng & Kau, 2021;Wu et al, 2020). followed by The United States of America (3;11%) (Gordon, Ward, Yao, & Lee, 2021;Redmond et al, 2021;Santarpia et al, 2020), Brazil (2; 7%) (Passos, Silveira, & Abrahão, 2021;Vicente et al, 2021) and Hong Kong, China (2; 7%) (Chan et al, 2020;Gormley, Aspray, Kelly, & Rodriguez-Gil, 2017).…”