International. In response to the coronavirus (COVID-19) pandemic, REHVA, the European Federation of Heating, Ventilation and Air Conditioning (HVAC) Associations, drafted the "COVID-19 Guidance" document on how to operate and use construction services in areas with coronavirus outbreak, to prevent the spread of COVID-19 depending on factors related to HVAC or plumbing systems.
REHVA called the document an "interim document that will be supplemented with new evidence and information when it becomes available." The precautions it contains are intended as an addition to the general guidance for employers and building owners presented in the World Health Organization document "Preparing Workplaces for COVID-19."
Crucially, the document states that humidification and air conditioning have no practical effect on COVID-19 transmission. Unlike other viruses, SARS-CoV-2, the virus that causes Covid-19 disease, is quite resistant to environmental changes and is only susceptible to high relative humidity above 80% and temperature above 30°C. Heating and cooling systems, according to the paper, can function normally as there are no direct implications on the spread of Covid-19.
The document includes practical recommendations for the operation of building services. In buildings with mechanical ventilation systems, it is recommended to increase the air supply and exhaust ventilation. In buildings without mechanical ventilation systems, it is recommended to actively use operable windows.
Under certain conditions, virus particles in the extracted air can re-enter the building. Heat recovery devices can carry viruses attached to particles from the side of the exhaust air to the side of the supply air through leaks. As a result, REHVA recommends turning off rotary heat exchangers during SARS-CoV-2 episodes. Virus particles in return ducts can also re-enter a building when centralized air handling units are equipped with recirculation sectors. Therefore, it is recommended to avoid central recirculation during SARS-CoV-2 episodes by closing the recirculation regulators.
Finally, the REHVA guidance document mentions that duct cleaning is not effective against room-to-room infection because the ventilation system is not a source of contamination if instructions on heat recovery and recirculation are followed.
According to the most recent research, Worldatlas specifies that "people who use their home's air conditioner are not at risk of infection, especially if they remain in their home without having contact with the rest of the population. But when it comes to central air conditioning, situations can vary. Central air conditioning, which is usually installed in larger commercial spaces such as shopping malls and more modern apartments, does not present any risk of spreading COVID-19 due to its technical properties, but possibly because it is usually used in crowded places. Researchers have studied the air conditioning system on the Diamond Princess cruise ship that had nearly half of the passengers infected with COVID-19. They discovered the virus particles on various surfaces around the craft. According to these researchers, the virus partially spread through the air conditioning system, as it could not filter out the virus particles. Still, this does not mean that it was the failure of the air conditioning system by the propagation. Simply, there was already an infection among the people on board, and the air conditioning helped spread while the passengers remained on the ship, using the same air conditioning system."
This information is not useless since, according to the website The Hindu, in Maharashtra, a state in the western peninsular region of India, the Minister of Health announced on March 21 that the government had issued circulars ordering people to restrict the use of air conditioning in the wake of the spread of COVID-19. "Windows should be left open for sunlight to enter, while air conditioners can be used where important," the circular says.
Other resources related to the operation and maintenance of heating, ventilation and air conditioning systems in the context of the spread of COVID-19 are available in particular from the following organizations:
- The China Refrigeration Association (CAR) published two recommendations including "Recommendations on the operation of air conditioning and heating systems coping with COVID-19", available on FRIDOC;
- ASHRAE has created a dedicated "COVID-19 Preparedness Resources" webpage;
- AHRI published the website "Coronavirus: Guidance for HR Professionals and Employers":
Finally, it should be noted that, in several countries, organizations have called on their governments to exempt heating, ventilation, air conditioning and refrigeration (HVAC/R) maintenance services from any restrictions that apply to travel and business operation during the COVID-19 crisis.
In the United States, AHRI and nine other organizations representing the North American HVAC/R industry petitioned on March 18 that federal, state, and local authorities grant "essential business" status to HVAC/R technicians and engineers.
In Australia, AIRAH has written to federal, state and territorial ministers and called on the government to clearly identify the maintenance of HVAC&R buildings as "essential services".
In Europe, ADC3R, ASERCOM, ECSLA, EHI, EHPA, EPEE and Transfrigoroute International, which represent the HVAC/R industry, have called on eu Member State governments to "consider their services and manufacturing sites as critical to maintaining the health, safety, productivity and comfort of citizens while taking measures to contain the spread of the COVID-19 virus".
The IIR, for its part, will soon issue a statement calling for refrigeration services to be considered essential during the current health crisis caused by COVID-19.
Source: International Refrigeration Institute.
