There will always be people who will take advantage of a crisis to sell something. Of late, we’re seeing some contractors, distributors and manufacturers touting ionization products (ozone generators, cold plasma, etc), HEPA filters, coil cleaning and UV systems as ways to prevent the spread of the novel coronavirus. Our customers are asking us about many of these products as a result. So, what really works and what can you do to leverage your HVAC systems to prevent the spread of SARS-CoV-2 (the virus that causes COVID-19)?
Our position, which as been echoed by ASHRAE, is that HVAC systems are not a primary contributor to the spread of viruses in most buildings so therefore are not the most effective place to stop their spread. There are some exceptions (isolation rooms, clean rooms, surgical suites, etc.), but for most buildings, following CDC guidelines around physical distancing, enhanced cleaning and good hand and respiratory hygiene is the most effective way to stop the spread of any virus, including SARS-CoV-2.
In addition to taking these steps, you may still want to know what else can be done, even if the impact is small. As a trusted advisor and partner to our customers, here is what McKinstry recommends:
- Increase ventilation by exchanging more outdoor air. This can increase the effective air dilution per person to help dilute aerosolized viruses. Our technicians can make the appropriate changes to equipment and controls settings. Caution must be taken to ensure the equipment capacity can still effectively heat or cool the space. This is a temporary fix—changes should be reversed once the crisis has passed to ensure you don’t alter efficiency of your systems, driving up energy costs.
- Consider portable room air cleaners with HEPA filters. Central HEPA filtration is expensive to add to existing systems and may not be capable of handling the additional static pressure without significant modifications. A better option may be to use portable HEPA air cleaners in localized settings where risk is higher.
- Ultraviolet Germicidal Irradiation (UVGI) can be used, particularly in high-risk spaces. Care must be taken to protect occupants from the UV radiation and from direct exposure of the UV light to people’s eyes. Placement is critical, as UV light will degrade many materials and can damage filters, plastic drain lines and pans, etc. However, if it can be installed safely and follows the system’s designed application, UVGI is very effective.
What about those products or measures that others are touting?
- Ionizing systems: Many of these systems produce ozone, but others use cold plasma, hydroxyl radicals or ionized hydrogen peroxide to kill bacteria and viruses. While extensive testing and EPA statements have called out the dangers of ozone to people’s respiratory systems, less is known about the long-term effects of these other systems. The bottom line is they all use oxidation as their primary method for killing bacteria and viruses and until more is known about the long-term health impacts of these other systems, we cannot recommend them for indoor use.
- Coil Cleaning: Keeping HVAC system coils clean is critical for their efficient operation and should be done as needed based on the environment those coils are in. While it is possible for particulates, including viruses and bacteria, to be found on coils, it likely won’t make much of a difference reducing the spread of viruses. This is especially true of coils on rooftop units where only particulates from outdoor air will be found.
- Central HEPA filtration: According to the Centers for Disease Control, the novel coronavirus spreads primarily through respiratory droplets when an infected person coughs or sneezes. Those droplets generally fall to the ground or land on other surfaces within six feet. While it is possible for viruses to become suspended in air for several hours and travel farther as a result, this is not the primary means of transmission. At this time, based on the cost and practicality of retrofitting HEPA filtration (which may require significant system modifications) when compared to any possible benefit, we can’t recommend this for most settings.
This is not to say there isn’t anything you can do. Physical distancing, hand and respiratory hygiene practices, and enhanced cleaning of surfaces can all prevent the spread of this and other viruses. If you want to do more, look to increase ventilation, use portable HEPA air cleaners and consider UVGI systems. We’re happy to help you with all these solutions, which are proven safe and effective. We can even talk to you about central HEPA filtration if you want to explore that option. But we simply can’t recommend any of the other “solutions” you may have heard of – don’t believe the hype.
Adam Gloss is the Director and General Manager of Service at McKinstry