Building / Facility Ventilation - Covid 19 Transmission (Bulletin)

Good afternoon,

On Sunday April 26, 2020 the National Post published a story on the transmission of the virus in HVAC systems.

I have for clarity attached directives from ASHRAE on the most current information on this topic.

In summary:

  • Maintaining RH levels in the 40-60% range is recommended.

  • This is the standard to which the buildings we are involved in are designed to.

  • Upgrading of filtration systems

  • We support, where the systems can handle the pressure drop, to upgrade the filtration to MERV 13. We would need to do site visits to ensure we wouldn’t be causing further problems.

Please note there is an extremely tight balance between fresh air / exhaust and drying a building out below the recommended 40% level. CustomAir strongly recommends this only be adopted once the systems have been reviewed to ensure we stay within the recommended standard.

Building Operators / Facility Maintenance Staff:

For companies with on site maintenance people or building engineers who are looking for guidance in operating ventilation systems we have created this overview:

Roles & responsibilities:


Building Operators who are looking for help to discover where opportunities for improvement exist in existing equipment to increase the effectiveness of building / facility system can call CustomAir’s service department for help.

Typically this would require a service call to establish the operating parameters of the site. It is important to note that both “flushing the building and increased filtration” will have impacts on building operations and costs. CustomAir has provided documentation and supporting data to show that besides the increased costs for materials like air filters and higher energy usage / costs, the impact of flushing a building will also draw the potential for lowering relative humidity (rh) and over taxing the building design for pressurization and the load on fans. Our buildings / facilities need to operate in the 40 – 60%rh range unless dictated by production requirements.

Areas to consider would be:

  • Review of “free cooling and minimum positioning inlet dampers” Each building has been specifically designed for this but it should be checked to see we are bringing in adequate fresh air

  • Elimination of “night set back or unoccupied” times. This will have a cost impact but will ensure the continuous movement of air and the introduction of fresh air.

  • Use of premium air filters. Depending on the fan system upgrading your air filters to a MERV 13 or 14 would be beneficial. It also comes with steep added costs as these filters are more costly and will be need to changed more frequently

  • Cleaning of evaporator or chilled / hot water coils. These are the coils in the air stream and depending on the type system in place should be looked at for cleaning.

  • UVC lights Installed in the air handling equipment or ductwork; while reportedly effective are extremely expensive and in many applications not practical

  • Running fans in the “on” position will ensure continuous proper air movement

Please contact technical support at CustomAir for more information and back-up documentation.

https://nationalpost.com/health/covid-19-likely-spread-by-building-ventilation-say-canadian-researchers-working-on-an-hvac-fix


https://www.pbctoday.co.uk/news/building-control-news/indoor-humidity-covid-19/74747/

https://www.ashrae.org/file%20library/technical%20resources/covid-19/eiband-airbornetransmission.pdf

https://www.ashrae.org/file%20library/about/position%20documents/pd_infectiousaerosols_2020.pdf

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CustomAir COVID Update #2 3/18/2020

Dear Valued Clients, Please find some additional resources that could help you during this time. https://www.canada.ca/en/public-health/services/diseases/2019-novel-coronavirus-infection.html?&utm_cam