This 2021 assignment for St Richard’s Hospice focused on "Assessment of a Natural Ventilation System for COVID-19 Risk of Infection" within the building and construction sector. Using computational fluid dynamics (CFD) and energy and thermal modelling, the team translated the existing project brief into a structured technical assessment. The work was intended to show why the system behaved as it did, how performance changed across credible scenarios, and which interventions offered the strongest engineering value.

The St Richards Hospice cares for people with a serious progressive illness who have complex needs that cannot be met by other care services. In line with modern engineering priorities, a flagship building and construction was designed to include the latest thinking in energy reduction technologies, such as natural ventilation. The aim of the investigation was to examine the impact and dangers of Covid-19 on the hospice's patients. Advanced computing expertise was used to help ensure that hospice patients are better protected from Covid-19 or similar future viruses following a pioneering study led by our team. The work developed a numerical framework and a new metric to assess the level of risk with high level of confidence, which can be used in all future ventilation designs for all similar large buildings. These findings will inform care managers and architects to create even safer environments as we look to manage living with Covid-19.

The methodology centred on a coupled airflow, thermal and aerosol-transport CFD framework for the naturally ventilated hospice. The representation retained occupied rooms, openings, circulation routes, heat sources and the flow paths through which exhaled aerosol could be diluted or transported. Boundary and operating conditions covered different natural-ventilation states, occupancy patterns, source locations, weather conditions and representative exposure periods, with material, fluid and equipment properties assigned from the available design information. Resolution was concentrated in regions where steep velocity, thermal, concentration or phase gradients were expected, while the overall model remained efficient enough to compare several credible configurations. This balance allowed system-level performance to be linked to the local mechanisms responsible for it.

The assessment compared window and door operation, ventilation strategy and practical management controls. Performance was judged using air-change and dilution, aerosol concentration, exposure and infection-risk indicators, stagnant zones and the spatial effectiveness of fresh-air delivery. Results were reviewed through quantitative summaries and engineering visualisations, such as contours, vectors, streamlines, sections and time histories, selected to suit the physics. Important assumptions and operating uncertainties were considered so that the recommendations relied on repeatable comparative trends rather than a single nominal case.

For St Richard’s Hospice, the principal value was a defensible risk framework and practical guidance for safer care environments during COVID-19 and future airborne outbreaks. The final evidence linked each recommendation to the relevant model or process output, making it suitable for internal design reviews, supplier or contractor discussions and, where applicable, planning, safety or regulatory dialogue. The work also created a reusable baseline that can be updated as geometry, operating data or test results become available, reducing the cost and risk of later design iterations.