The scientific community still lacks knowledge about COVID-19. But based on what we already know, both the World Health Organization and the Portuguese Ordem dos Engenheiros (Engineers’ Order) recommend a series of measures to prevent the spreading of COVID-19 in buildings. In addition to social distancing and other prevention measures in facility management, maintenance managers should take extra care with HVAC systems (heating, ventilation and air conditioning) and water distribution.

All the measures that we will talk about for facility managers are valid for residential and non-residential buildings where large numbers of people are gathered, such as offices, hotels, schools or shopping centres. Hospitals, health centres, clinics and other places of clinical activities should always follow the latest guidelines and regulations from the government.


Is it possible for COVID-19 to spread in buildings?

Short answer: yes. So far [as of 9 April 2020], we know of at least three methods of SARS-CoV-2 infection (the virus that causes COVID-19):


  • Direct contact with an infected person or surface, if afterward the hand comes into contact with a mucous membrane (mouth/ nose/ eyes);


  • Inhalation of viral droplets, which infected people expel when they talk, cough or sneeze (which can stay up to 3 hours in the air and spread for several meters);


  • Oral-fecal contamination (acknowledged in March, since the virus is excreted in feces).


It is in these last two forms of contamination that facility managers need to focus on. We know that SARS-Cov-2 has been detected in the exhaust ducts of wards and COVID-positive zones (i.e. intended to treat patients with the disease). This reaffirms the hypothesis that particles are projected much farther than 1-2 meters in enclosed spaces and forces us to re-evaluate the best way to ventilate these spaces.


On the other hand, the particles entering the water distribution system were an active transmission route of SARS-CoV-1, the virus responsible for the outbreak of SARS in 2002-2003 in Asia. The transmission of SARS through pipelines was proven in Hong Kong, where 107 people living in the same vertical block of flats were infected by the virus. Therefore, and yet without certainty about the airborne transmission of SARS-CoV-2, European norms call for an ALARA (“as low as reasonably achievable”) approach to risk, which means that prevention is the way to go.


Maintenance management measures to prevent the spreading of COVID-19 in buildings and workplaces

Based on the information available to us, these are the recommended procedures that maintenance managers should adopt to prevent the spread of COVID-19 in buildings through HVAC systems. (Note: As we find out more about COVID-19 and the behavior of SARS-CoV-2, it is expected that the instructions of REHVA will be reviewed and improved).


Ventilation and air extraction during the COVID-19 epidemic

The best way to ensure that viral particles do not “hover” in common areas is to increase the ventilation of buildings and extract the air:


  • Turn on the ventilation 24/7, even at a low rate;


  • If possible, to avoid oral-fecal contamination, ventilate the toilet facilities with negative pressure;


  • Open the windows more than usual, even if it may compromise thermal comfort, especially in rooms that have been previously used by third parties;


  • In case a room has been occupied by someone with a suspected or confirmed infection of COVID-19, it should be aired naturally for at least 3 hours.


Air Recirculation in HVAC & Heating Systems

Since the SARS-CoV-2 particles can remain in exhaust ducts, it is essential to avoid air recirculation in HVAC systems to prevent COVID-19:


  • In Air Handling Units that take advantage of the air and recirculate it, the mixing sections must be closed even if they have filters (since these are non-HEPA filters that let SARS-CoV-2 microparticles through);


  • Ventilation fans must be switched off or, if this is not possible, they must be thoroughly disinfected;


  • Heat exchangers and heat recovery devices must be switched off, except for systems that can fully separate the intake and return air;


  • Air purifiers only work in very small rooms (<10 m2) and therefore only provide benefits if they are installed very close to people – overall, adequate space ventilation offers many more benefits;


  • You should install HEPA filters in windowless rooms and in closed circuits, which are the only ones capable of filtering out virus microparticles.


Changing your maintenance plan because of COVID-19?

  • There is no advantage in doing additional duct cleaning as long as you avoid 100% of air recirculation and ventilate the rooms. Clean and sanitize the ducts as planned.


  • Replace the filters only when they have exceeded their usable time or there is a break in the load input. There are no advantages in changing it more often if there are no malfunctions in the filter performance.


  • There is no need to change the external filters as current ventilation systems have F7, F8 or ISO ePM1 filters. If you have any questions, please see the technical details of the equipment to confirm.


  • Maintenance personnel should wear masks, goggles, and gloves to replace the filters, as they can reservoirs for the virus. You should always assume, even in normal public health situations, that the filters have potentially contagious microbiological material.


  • The filters must be stored in sealed bags.


  • Ionisation or UV disinfection is not recommended for common buildings and only makes sense in a hospital setting.


Water distribution and contamination of COVID-19 through plumbing

Problems in the water distribution system and in the pipelines enhance the possibility the fecal-oral contamination. So there are two things you should pay attention to:


  • Always flush the toilet with the lid closed to prevent the propagation of particles;


  • Prevent siphons from running out of the water and maintain the water level, which prevents discharges and virus particles from “re-entering” the environment – to do so, use all water points every three weeks.


Humidity and temperature regulation to prevent COVID-19

Although some viruses are highly sensitive to changes in humidity and temperature levels, the new coronavirus is especially resistant. SARS-CoV-2 is only sensitive to humidity above 80% and to temperatures above 30ºC, which are not viable conditions for office buildings (nor for housing patients). Therefore, it is not worth making adjustments to humidity and to the temperature of the air conditioning to prevent COVID-19.