Written 31 March 2020
Building services during COVID-19 emergency. A summary of the guidelines drawn by experts from REHVA (Federation of European Heating, Ventilation and Air Conditioning Associations).
The aim of these guidelines is to provide HVAC professionals and facility managers, with information on how to operate and use building services in areas with a corona virus. These guidelines will help to prevent the spread of COVID-19 depending on HVAC or plumbing systems related factors.
Small particles can travel long distances carried by airflows in the rooms or in the extract air ducts of ventilation systems. Although currently there is no evidence for Corona disease (COVID-19) infection via this route, there is no data ruling out this possibility either. There is one indication, though. Corona virus SARS-CoV-2 has been isolated from swabs taken from exhaust vents in rooms occupied by infected patients. Hence, we should implement the following suggestions as much as we can.
How to run building services during COVID-19 emergency
Increase air supply and exhaust ventilation
- Extending operation times is an important recommendation.
- A even better solution is to keep the ventilation on 24/7.
- Exhaust ventilation systems of toilets should be on 24/7.
- Supply as much outside air as reasonably possible.
- Reduce the number of employees (increase the air volume pro-capita).
Use more window airing (when mechanical ventilation is not present)
- Open windows (much more than normally, even when this causes some thermal discomfort).
- It is important to keep windows open in different spaces in order to achieve cross flows throughout the building.
Humidification and air-conditioning have no practical effect
- COVID-19 is resistant to environmental changes and is susceptible only for a relative humidity above 80% and a temperature above 30 ˚C. That is not attainable and acceptable in buildings for thermal comfort.
Safe use of heat recovery sections
- Rotary heat exchangers (including enthalpy wheels) should be (temporarily) be off during SARS-CoV-2 episodes.
- If there is a suspect of leakage in the heat recovery sections, pressure adjustment or bypassing can be an option in order to avoid a situation where higher pressure on extract side will cause air leakages to supply side.
No use of recirculation
- Virus particles in return ducts can also re-enter a building, close the recirculation dampers.
- This may lead to problems with cooling or heating capacity, but it is more important to prevent contamination and protect public health than to guarantee thermal comfort.
- De-centralized systems such as fan coil units that use local recirculation, also should be off to avoid resuspension of virus particles at room level.
Duct cleaning has no practical effect
- Small particles containing viruses would not deposit easily in ventilation ducts as they are normally carried out by the air flow anyhow.
Change of outdoor air filters is not necessary
- The size of a coronavirus particle of 80-160 nm (PM0.1) is smaller than the capture area of Fine filters (capture efficiency 65-90% for PM1)
- SARS-CoV-2 particles also aggregate with larger particles which are already within the capture area of filters
- In rare cases of virus contaminated outdoor air. Fine outdoor air filters provide a reasonable protection for a low concentration and occasionally spread viruses in outdoor air.
- From the filter replacement perspective, normal maintenance procedures can be used.
- Clogged filters are not a contamination source in this context, but they may reduce supply airflow which has a negative effect on indoor contaminations itself. Thus, filters must be replaced according to normal procedure when pressure or time limits are exceeded.
Room air cleaners can be useful in specific situations
- To be effective, air cleaners need to have at least HEPA filter efficiency
- Devices that use electrostatic filtration principles (not the same as room ionizers!) often work quite well too.
Please note
These recommendations can only compliment the general guidance for employers and building owners presented in the WHO document ‘Getting workplaces ready for COVID-19’.
For more detailed information please refer to the REHVA documents and web pages below.
Please find below link to REHVA web page with guideline document and bibliography.
https://www.rehva.eu/activities/covid-19-guidance
To download the Guide line please click the below link:
https://www.rehva.eu/fileadmin/user_upload/REHVA_covid_guidance_document_2020-03-17_final.pdf
To download the Bibliography please click the below link:
https://www.rehva.eu/fileadmin/user_upload/REHVA_COVID-19_guidance_document_Bibliography.pdf
