Right now, people in cities across the world are asking, ‘Is my building safe to occupy?’

The COVID-19 Delta variant is more transmissible than the original strain, particularly in an aerosolized context. Clients ask us what they can do to make their schools and workplaces safer for occupants. This question has brought building ventilation systems into focus. Is there more that we should be thinking about to assess and minimize the risks?

Risk Assessment for reducing the spread of COVID-19

For the past 18 months, we have started to look outside of the traditional engineering viewpoint. Our HVAC engineers know how to design every kind of ventilation system – for any purpose and in a range of different building types and sectors. While our skills and experience give us the tools to solve the engineering challenges of air conditioning and ventilating buildings, we are not experts in viral transmissibility – whether COVID-19 or any other virus.

We are working closely with an occupational hygienist, who is also engaged by the Victorian Government, to assess and propose modifications to the buildings selected as part of the hotel quarantine system. How can this thinking be applied to all buildings?

Through a risk-based analysis of existing and proposed buildings and their HVAC systems, we can ascertain the suitability of the spaces to be reoccupied and the associated potential level of virus transmission risk.

One size doesn’t fit all

We must undertake this analysis on a space-by-space basis. The varying nature of the systems, environmental conditions, and the building’s architecture all impact the best outcomes to minimize COVID-19 in the space.

For some spaces we have assessed, HEPA filters were a viable option to improve ventilation; other areas had been designed with fully operable windows that passively expelled contaminants. We observed that one school benefitted from only being occupied for 45 minutes before a 15-minute break to reduce pollutants through the assessment process.

The recommendations will revolve around factors such as:

  • Effectiveness of existing ventilation systems
  • Control measures to improve ventilation effectiveness
  • Where beneficial – proposed system modifications or upgrades – based on a cost/benefit analysis
  • Operational measures to reduce risk of exposure such as:
    • Density of occupants
    • Period of occupancy and associated vacant times
    • Benefits of using masks and other PPE
    • Cleaning and sterilization of surfaces
    • and more…

Using the recommendations of the occupational hygienist, our team can help design an HVAC system that can get our kids back in the classroom, safely.


Get in touch with Principal Hugh Wilson here to learn how a COVID-19 risk assessment from an HVAC engineer and occupational hygienist could improve your space.