The Design and Simulation of Natural Personalised Ventilation (NPV) System for Multi-Bed Hospital Wards

Abstract

Adequate ventilation is necessary for thermal comfort and reducing risks from infectious bio-aerosols in hospital wards, but achieving this with mechanical ventilation has carbon and energy implications. Natural ventilation is often limited to window-based designs whose dilution/mixing effectiveness are subject to constraints of wind speed, cross ventilation, and in the case of hospital wards, proximity of patients to external walls. A buoyancy-driven natural ventilation system capable of achieving dilution/mixing was shown to be feasible in a preceding study of novel system called natural personalised ventilation (NPV). This system combined both architecture and airflow engineering principles of space design and buoyancy and was tested and validated (salt-bath experiment) for a single bed ward. This research extends the previous work and is proof-of-concept on the feasibility of NPV system for multi-bed wards. Two different four-bed ward types were investigated of using computational fluid dynamics (CFD) simulations under wind-neutral conditions. Results predict that NPV system could deliver fresh air to multiple patients, including those located 10 m away from external wall, with absolute flow rates of between 32 L·s for each patient/bed. Compared to same wards simulated using window design, ingress of airborne contaminants into patients' breathing zone and summer overheating potential were minimised, while overall ward dilution was maximised. Findings suggest the NPV has potentials for enabling architects and building service engineers to decouple airflow delivery from the visualisation and illumination responsibilities placed upon windows. OPEN ACCESSBuildings 2015, 5 382

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

“…The PMV index is the most comprehensive thermal environment evaluation index at present. The specific calculation method is shown in Formula (8).…”

“…COVID-19 is mainly transmitted through the respiratory tract, so it is necessary to focus on the control of infectious sources and maintain high indoor air quality. Therefore, the transformation of the ventilation system in the Fangcang shelter hospital is an extremely important part of the construction of the Fangcang shelter hospital [8].…”

Ventilation strategies and design impacts on indoor airborne transmission: A review

“…This study highlighted low-cost and straightforward architectural modifications, such as extra windows to provide cross NV and an open skylight in clinical areas, can improve ACH and noticeably improve NV performance and significantly decrease aerosol transmission risk. A novel strategy named Natural Personalized Ventilation (NPV) has also been presented as an architectural modification to provide clean air for patients in hospital wards [ 148 , 149 ]. NPV is a buoyancy-driven NV that delivers new outdoor air directly over a patient bed using an elevated duct.…”

Experimental comparison of local low velocity unit combined with radiant panel and diffuse ceiling ventilation systems

“…PV installed at workstations provides the clean air close to each occupant’s breathing zone and has the potential to improve inhaled air quality. 42,49,50 Recently, local hospital bed ventilation 51,52 and natural personalized ventilation 53 were introduced to meet the individual indoor air quality requirements and avoid airborne cross-infection. Also, other types of personalized ventilation systems were introduced, e.g.…”