The COVID-19 pandemic is forcing people around the world, in all walks of life, to reevaluate strategies for conditioning interior space. Traditional methods and typical ventilation rates are often insufficient to significantly reduce the viral load in a space before it can spread across the occupants.
Three major strategies should be considered – Flush, capture, and kill. Briefly explained below, these strategies can often be combined to yield significant gains in air quality.
Flush: Because outdoor air is typically low in germ contamination, increasing outdoor air percentage while exhausting contaminated air from the building can help to remove existing virus from a space as well as slow its concentration. However, this approach is costly in terms of energy required to condition all that outdoor air – cooling in the summer, heating and humidification in winter. Consult a professional engineer to ensure your existing air system can handle the increased outdoor air percentage while maintaining the desired temperature and/or humidity level in the building.
Capture: Improved air filtration can be a means of reducing aerosol viral load in a space. This requires installation of HEPA filtration in the air systems serving the target spaces, or standalone HEPA air filtration equipment in the space. HEPA filters typically require more fan power than any other common HVAC filter type, so an existing system may not be able to maintain sufficient airflow without further modifications. Consult a professional engineer to analyze your system(s) and determine appropriate solutions for your unique condition.
Kill: UVC light is a proven method of reducing viral loads in HVAC airstreams. This method has not been conclusively proven effective against COVID-19, but testing thus far is promising and this is an established technology with products available from many experienced and qualified vendors. Care must be taken in design to ensure UVC modules are sized and located properly to ensure maximum effectiveness. Consult a professional engineer to assess your HVAC system(s) and recommend viable solutions.