The design and simulation of natural personalised ventilation (NPV) system for multi-bed hospital wards

© 2015 by the authors. 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-1 and 54 L·s-1 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.