COVID-19 Updates: uc.edu/publichealth
HVAC - Indoor Air Quality
ASHRAE is a global society that establishes standards and best practices to improve building services engineering, energy efficiency, indoor air quality, and sustainable development. Here is a link to a recent document released by ASHRAE – “Guidance for Building operations during the COVID-19 Pandemic.” This article states that “HVAC systems in most non-medical buildings play only a small role in infectious disease transmission, including COVID-19. Even though the HVAC systems only play a small role, FM is still taking recommended steps to reduce the threat of transmission from these systems.
- Facilities Management has a preventive maintenance schedule and procedure that we adhere to for all of our building HVAC systems. This includes filter changes, coil cleaning, component checkout, and sequence of operation verification.
- We operate our HVAC systems through a building automation system (BAS). The BAS is programmed to bring in the design volume of ventilation air (outside air) per designed occupancy load. We verify this control operation during our preventive maintenance routines as well as when any deviation is indicated via alarm.
- There are occupancy schedules or occupancy switches in our buildings to put our HVAC systems into an occupied mode (design ventilation levels) when there are occupants in the building.
- We will continue to operate all our HVAC systems. ASHRAE has reported that shutting down HVAC systems is not recommended.
- “Ventilation and filtration provided by heating, ventilating, and airconditioning systems can reduce the airborne concentration of SARSCoV-2 and thus the risk of transmission through the air. Unconditioned spaces can cause thermal stress to people that may be directly life threatening and that may also lower resistance to infection. In general, disabling of heating, ventilating, and air-conditioning systems is not a recommended measure to reduce the transmission of the virus.”
Frequently Asked Questions
Will HEPA filters be installed in all UC HVAC systems?
No. HEPA filters are very dense and create a large pressure drop in the air handler. If they were installed in an air handler that was not designed for them, then we would have significantly reduced air flow, including the ventilation air flow. Also, it should be noted that no filter is 100% efficient including HEPA filters.
Will all of our recirculating air systems be changed over to 100% outside air units?
No. A system would have to be designed to be 100% outside air (as is true in all our research buildings) to be able to maintain indoor air temperatures and humidity levels. Just switching a unit to 100% outside air could create other indoor air quality issues or damage equipment during extreme outside conditions.
Our systems do switch to an economizer mode to save energy, but this also increases the volume of outside air brought into a building during these applicable outside air conditions.
Can occupants bring in their own room air purifiers for use?
We do not currently have a policy prohibiting these devices. Overloading electrical circuits could be a problem.
Is the University looking into UV-Lighting to use as a disinfectant tool?
We are aware of the technology and are researching how beneficial this technology may be for our campus environment. However, with over 13,000,000 square feet of conditioned space it may not be feasible.
Will the university be reducing airflow so that COVID-19 is not blown around?
We will not be reducing the airflow in buildings as this will cause mold and other issues. This change would also reduce the ventilation air being brought into the building.
Is there an effort being made toward reducing energy use in empty or low occupancy buildings?
Through the use of the BAS we are reducing energy consumption in unoccupied buildings as well as maintaining a minimum standard to prevent excess humidity or temperatures.