Practical HVAC Operational Measures to Reduce the likelihood of Spreading COVID-19 in Commercial Buildings

Several Commercial Real Estate clients I support have asked me for guidance on how they should operate the HVAC systems in their commercial office buildings during these unprecedented times. Over the last two weeks I’ve actively researched best practices for addressing stakeholder concerns regarding the operation of the heating, cooling, and ventilation systems to support healthy and safe environments in commercial office buildings.

Best resources I've found:

• “Coronavirus disease (COVID-19) Advice for the Public” - World Health Organization (March 18, 2020)
•  “Guidance for Building Operations During the COVID-19 Pandemic” - Lawrence J. Schoen, P.E., Fellow/Life Member ASHRAE (ASHRAE Journal Newsletter (March 24, 2020)
•  “HVAC and COVID-19 Explained” – Matthew Peacock, P.E. (A.G. Coombs Group, March, 2020)

 What I learned:

How the Corona virus is transmitted is not fully understood at this time. It is believed that the virus can be transmitted from person-to-person, most likely through close contact with an infectious person, or contact with droplets of fluid from an infected person’s cough or sneeze. It is also believed that transmission can occur by touching surfaces that have droplets from an infected person, and then touching the mouth or face.

When a person infected with an illness coughs or sneezes, pathogens can be encapsulated within droplets of fluid and discharged into the air. Different illnesses are known to result in differing droplet sizes. It is not yet certain what size droplets are produced by people infected with COVID-19.

It is known that large droplets (>60 micrometers) normally are too large to remain suspended in the air and usually fall and land on surfaces. Best estimates are that the Corona virus may survive for up to 9 days on some surfaces in the right conditions. In some instances, fluids can evaporate, and the large droplets can transform into smaller particles and these can remain suspended in air. These “droplet nuclei” (between 2.5 to 10 micrometers) are believed to be able to remain suspended in air for hours and therefore, in theory, can be entrained into HVAC systems. Published research on ventilation systems suggests that the transmission of droplets containing viral material is theoretically possible, it is thought to be less likely in a typical properly maintained HVAC system in commercial buildings.

Heating, Ventilating, and Air Conditioning (HVAC) equipment fundamentally create recirculating systems where a portion of outside air added continually while a similar portion is exhausted. The amount of outside air can often be varied. Air is filtered before recirculation and distributed throughout the building using system fans. Air filtration typically installed in standard HVAC systems will not be effective in filtering droplet nuclei or viruses, should these reach the filters.

Increased ventilation (circulation) rates can assist in diluting contaminants in room air and potentially reduce the likelihood of infections. It should be noted that increasing outside air and ventilation rates will generally result in increased energy usage and in some circumstances may result in difficulties in the system maintaining the desired internal temperature and humidity conditions.

Summary of Recommended Activities

• HVAC preventative maintenance should be carried out as prescribed. Review of the preventive maintenance inspection records would be prudent to confirm duty of care responsibilities have been met in the operation of the facility.
• It is important to verify that HVAC equipment and Energy Management Systems (EMS) are operating correctly.
• Check the outside air flow rates and controls to confirm that the minimum outside air rates are being achieved as a basic requirement and ideally, if possible, increasing the outside air rates.
• Disable demand-controlled ventilation (DCV) where applicable.
• Conduct an audit of the HVAC system filtration. Confirm use of or consider upgrading to filters with an improved Minimum Efficiency Reporting Value (MERV) between 13 and 15.
• Develop an "enhanced" HVAC and Energy Management Systems operational "Game Plan" that can be communicated to all stakeholders.*
• Create and disseminate several communications geared toward sharing what you are doing to ensue your building’s HVAC system is supporting a healthy and safe environment for all occupants.*

* Energy Guy best practice recommendations.

?Bottom Line - It appears that HVAC systems can be used to assist in reducing the spread of the Corona virus infections as part of a broader multi-modal strategy in commercial buildings. Make sure to communicate what you've done to support good indoor air quality to all stakeholders as we begin to reoccupy commercial properties.

The Energy Guy team is currently scheduling complimentary Indoor Air Quality inspections /consultations. Please just let us know if we can be of any assistance.

Stephen (aspiring to become your go-to Energy Guy)

EnergyGuy.com

"Energy and Persistence Conquer all Things" - Benjamin Franklin