Active Projects

The feasibility of natural ventilation in healthcare buildings

Project Facts

Start date: July 2009
End date: June 2013
Investigators Professor Andrew Price; Dr. Malcolm Cook
Staff Employed Zulfikar A. Adamu
Status Completed

Project Partners

• Great Ormond Street Hospital
• NHS Skipton House, London
• Department of Health - Activity Database (ADB)

Project Partners

Department of Civil and Building Engineering
Loughborough University
Ashby Road
LE11 3TU
T: +44 (0) 15 0922 2627

The indoor air quality (IAQ) needs of modern hospital wards are very complex. The research investigated the potential of existing and innovative natural ventilation systems to deliver thermal comfort through low energy heating and deliver required airflow rates that should protect occupants from airborne pathogens. Three kinds of single-bed wards were investigated: the generic design from activity database (ADB); a proposed design by healthcare architects (Short and Associates); and the as-built design of the Great Ormond Street Hospital (GOSH). Four natural ventilation systems were explored using dynamic thermal modelling (DTM) and computational fluid dynamics (CFD). These systems include: single opening systems and dual opening systems that are together classified as simple natural ventilation (SNV); the inlet and stack or advanced natural ventilation (ANV) systems as well as the novel natural personalised ventilation (NPV) system. All these systems were modelled and simulated in the three types of ward identified in order to measure predicted performances in terms of airflow rates, thermal comfort, heating energy as well as distribution of generic (surrogate) airborne pathogens.

The research contributed to the body of existing knowledge by shedding light on the limitations and potentials of single and dual openings, especially in the context of existing wards for refurbishment purposes. The research provided insights into satisfactory trickle ventilation rates for winter periods when dilution of indoor air is required without significant heating energy penalties. The role of en-suite bathrooms acting as unintended obstacles to the unimpeded flow of fresh air in displacement natural ventilation systems (like the ANV) was also found.

In view of the limitations of SNV and ANV systems in protecting susceptible patients from airborne pathogens, the NPV system was specifically developed to deliver adequate ventilation rates to each patient who is being protected by a localised ceiling-mounted supply of fresh air. This concept was in fact, inspired by Florence Nightingale, who stated that the first rule of nursing was to keep the air within as fresh as the air without. The NPV was thus developed to take fresh air to where it was specifically needed: around the patient. By happenstance, NPV system was also found to achieve a mixing regime, which is not commonly associated with buoyancy-driven natural ventilation. This mixing occurred due to continuous dropping of dense fresh air which had to escape via a high-level stack delivering two more benefits: better dilution of ambient room air and lower heating energy expended in winter or cold periods. The flow regime (personalised delivery and dilution) offered by the NPV system was also validated using salt-bath experiments.