How can we equip HVAC units to fight coronaviruses?

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Opinion

  Posted by: electime      15th June 2021

There is a debate raging in scientific circles about just how much of a role HVAC systems have had in the spread of Covid-19. And although nothing is resolute just yet, it seems a bad bet to claim that air-conditioning units have had no effect — and particularly in closed indoor spaces — on the spreading of virus particles.

When the pandemic began, it didn’t take long before fingers pointed the blame at air-conditioning systems. A superspreader event traced to a restaurant in Guangzhou, China, seemed to suggest that a lone diner with no symptoms could have infected others by coughing too close to a HVAC fan. And of course, there is the story of the Diamond Princess cruise ship, which made headlines all over the world last February. It seems almost certain that the ship’s interconnected HVAC system helped Covid rip through the ship population.

Because HVAC units typically operate indoors, and because the coronavirus is capable of lingering in the air in the form of respiratory droplets, it’s no wonder people have questions and concerns. In fact, these concerns have prompted the European Federation of Heating and Ventilation Engineers (REHVA) organisation to publish information and set out guidelines on what we can all do to make air-con units allies in the war against Covid, and not adversaries.

It turns out we need more air-conditioning, not less

Despite all of the doom and gloom of the above paragraphs, REHVA does not recommend simply switching off your air-conditioning or dismantling the systems. In fact it recommends the opposite. What we need to do is equip our HVAC units so that they can literally blow viral particles away, in order to stop them from lingering, and settling down to make ‘fomites’ (surfaces that are infectious to touch).

That means air-conditioning units will have to be reconfigured, to increase the amount of fresh air they pull in from outside. This fresh air must then be redistributed indoors at a quicker rate than before — ensuring that there is a swift and constant exchange of air inside and outside.

The ‘open windows’ debate

The oldest form of air-conditioning is, of course, the open window. And opening the windows is a sure-fire way of making sure air is frequently swapped out and exchanged in a closed space. But as we all know, opening windows are very often far from practical. For example, an open window won’t mean very well in a noisy or polluted or cold environment. They can even be hazardous if there is a risk from falling.

Open windows are good and all if there’s no trouble in having them open. But even then, a properly set up HVAC system will still be a safer, more comfortable alternative on all accounts — including in helping to clear away coronavirus particles.

Are we about to see the widespread use of even safer HVAC units?

The most proficient air-con units in the world are equipped with HEPA (high-efficiency particulate air) filters. Currently, these HEPA systems are largely restricted to surgical chambers and aeroplanes, where getting the appropriate amount of air-exchange is already a matter of health and safety.

HEPA filters consist of thousands of fine layers that ensnare particles ranging from dust, to fungi, to viruses. They operate so quickly that a room’s air supply is completely turned over up to 30 times an hour. Right now they are pretty niche, and there are also some technical issues to work out, such as how to stop the filter from “dragging” on the air-recycling system, but thanks to the coronavirus pandemic they could soon be mainstream. In short, HEPA filter-equipped HVAC systems could be just one more facet of the “new normal.”

Protecting the public with air-conditioning

HEPA filters aside, we don’t have to wait around to make our air-conditioning systems better suited to keep us safe from Covid-19. We can do that right now, equipping and reconfiguring our units to make our indoor spaces safer and fomite free.

The coronavirus finds it hard to spread and infect outdoors. That means most of the spreading must take place indoors. That means it is imperative that we take action to help limit the spread.

This advice is not intended purely for the coronavirus. After all, the flu and other nasty illnesses come and go every year — and there will be more to come. With REHVA’s guidelines in mind and a bit of awareness, we could probably prevent countless unnecessary infections every year.

In summary, the advice is short and sweet: to keep an enclosed indoor area safe from lingering viruses, just turn your air-conditioning unit up. Blow them away with freshly exchanged air from the outside.


About the Author

Mark Kaufmann writes for ADK.co.uk, a London-based air-conditioning and fridge-freezer business.