HVAC Protocol, 2020-21

Issued July 17, 2020; Revised November 13, 2020


In order to protect Albemarle County Public Schools (ACPS) staff, students and teachers from the COVID-19 virus, the division has changed the operation of HVAC equipment in accordance with nationally recognized guidance documents. ACPS is utilizing guidance from the following resources:

ASHRAE, through its Environmental Health Committee, created the Epidemic Task Force, and has issued the following statements:

  • Statement on airborne transmission of SARS-CoV-2: Transmission of SARS-CoV-2 through the air is sufficiently likely that airborne exposure to the virus should be controlled. Changes to building operations, including the operation of heating, ventilating, and air-conditioning systems, can reduce airborne exposures.
  • Statement on operation of heating, ventilating, and air-conditioning systems to reduce SARS-CoV-2 transmission: Ventilation and filtration provided by heating, ventilating, and air-conditioning systems can reduce the airborne concentration of SARS-CoV-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.


Building Services operates and maintains HVAC systems for the division. The Building Services team programs and operates the Building Automation System that controls the HVAC operations.

Energy Management Technicians – Responsible for programming the Building Automation System for increased outdoor air delivery and monitoring system performance.

HVAC Technicians – Responsible for evaluating and installing filters with increased MERV filter ratings where possible.


ASHRAE: American Society of Heating, Refrigerating, and Air-Conditioning Engineers
CDC: Centers for Disease Control and Prevention
DOAS: Dedicated Outdoor Air Systems


The following measures have been implemented for ACPS facilities.

A. Outside Air Delivery

ACPS schools have a variety of HVAC systems with varying capabilities of changing the amount of outside air delivered to each space. ACPS will double the amount of outside air for systems that are adjustable.

Demand-based systems that traditionally deliver outside air based on the carbon dioxide (CO2) levels will be programmed to allow an increased amount of outside air.

To account for the increased outside air, the cooling and heating setpoints may be adjusted from the ranges in Board Policy FEH, Energy Management and Conservation.

B. Preventive Maintenance

ACPS is focused on preventive maintenance (PM) for existing systems to ensure they are in excellent operating order. The Building Services Department has been focused on the following PM items as a high priority:

  • Maintaining proper system operation
  • Systematically executing system filter changes
  • Executing preventive maintenance & coil cleaning
  • Daily building flush (Building runs in occupied mode before and after building occupancy)

C. Running HVAC Systems Pre & Post-Occupancy

The HVAC systems will be operated before and after the occupied periods to allow additional flushing of the building. Elementary school HVAC systems will run in occupied mode from 5 am until 10 pm. Secondary school HVAC systems will run in occupied mode from 6 am until midnight.

DOAS units will be operated 24 hours per day during the school week to allow additional flushing.

D. Increase MERV Filter Ratings

ACPS increased efficiency filters on existing equipment.

E. Portable HEPA Filtration Units in Clinics

A medical grade HEPA filtration unit with UV light is installed in each health annex. The unit will clean the air in a space approximately every 3 minutes.

F. HVAC Operational Response to Positive COVID-19 Case

In response to a positive COVID-19 case in a school facility, the HVAC systems will run overnight to allow additional building flushing.

G. HEPA/Ionization Units in Classrooms

Portable HEPA filters with ionization have been added to all classrooms.

ASHRAE’s guidance for reopening schools suggests installing portable HEPA units where HVAC systems cannot accommodate a MERV 13 filter, which will be the case for some ACPS systems.

HEPA filters are certified to capture 99.7% of particles that are precisely 0.3 microns in diameter. The coronavirus alone is 0.125 microns, but some of the droplets that carry the virus are greater than 0.3 microns. The research on the virus droplet particle sizes is still underway, but a recent study (Bioaerosol Size Effect in COVID-19 Transmission) provides a good breakdown of the virus-laden particle sizes. Another study found that air purifiers were able to reduce the aerosol concentration by more than 90% within less than 30 minutes.

Questions? Please call Building Services at 434-975-9340 with questions about our HVAC practices.