Professional Comment

Re-engineering HVAC Units for a Post-Coronavirus World

By Mark Kaufmann, senior copywriter at ADK Kooling (

As you likely know, a disproportionate number of global Covid-19 deaths occurred in care homes. And given the virus’s semi-airborne ability to drift through enclosed spaces on respiratory droplets, it’s no wonder that a growing amount of experts are calling for a review of ventilation practices in order to better protect people living and working indoors. This is especially important as we approach the ‘new normal’ life; one back to the regularity of frequent visitors — most of whom will need protect- ing before visiting to keep themselves and the most vulnerable safe.

Because ventilation plays a role in how the virus can spread, the European Federation of Heating and Ventilation Engineers (REHVA) has set out some guidelines to help specialists and employers, so that they can optimise their HVAC units to limit the spread of the virus.


A lot of people tend to think that if air conditioning units can help with the spread of viruses, then they should be turned off. But the opposite is true. They should be turned up. Way up. And that is the advice of REHVA. The ‘internal air’ of indoor areas should be diluted as much as possible to blow viral particles away before they can settle on any surface.

What’s key is that air conditioning units be optimised to increase the rate at which air is pulled in from out- side and supplied quickly and readily throughout the interior space, to get a good air exchange and frequent recycling of air. In short: if your air-conditioning system is normally on recirculation mode, then it should be configured to run on full outside air — if that’s possible.

Of course, many experts argue that simply opening the windows will also do the trick. But in care homes, we have to consider that this is not really possible during the colder months or in areas of high air pollution,

and could do as much harm as good. And in some buildings, depending on the window type, it just isn’t practical. But even if you have the optimal environment to keep the windows open, air-conditioning units should still offer a better and cleaner alternative.


The most efficient air-conditioning units have high-efficiency particulate air (HEPA) filters. These filters operate on planes and in surgical theatres.

HEPA filters work by sucking viruses, fungi, dust and other pathogens through millions of particle-grabbing layers. This combined with a frequent flux of fresh air often means that an indoor environment can experience a near-total change of air up to 30 times an hour.

HEPA filters are not currently a common feature in care homes or indeed in any environment beyond ultra- specialised situations such as planes and hospitals. But that’s not to say their implementation isn’t being dis- cussed. At present, the biggest challenge is working out a way to implement them into traditional HVAC units in such a way that their many filters won’t “drag” on and reduce the efficiency of the airflow — a consequence that would actually be self-defeating. So watch this space.


In the meantime, does coronavirus even spread via air-conditioning units? Actually, there is no confirmed evidence at present. But scientists have every reason to suspect it does. For example, in February of last year, when the Diamond Princess cruise ship was quarantined, many scientists suspected the ship’s air-conditioning to be behind the rapid spread of the virus on board.

There are other outbreaks over the last year where scientists have pointed the air-conditioning as a likely assistant in the spreading of coronavirus. What is important, then, is that care needs to be taken going forwards, in how we optimise and adjust our HVAC units.

For safety and efficiency, it is the duty of care home owners and engineers to carefully calculate the rate at which viruses have the potential to replicate, and to counter this with a more than appropriate rate of incoming, freshly circulated air. In short, adjust settings, and turn it up.