COVID-19: Frequently Asked Questions (FAQs)

Measures being taken address ventilation, filtration, administrative controls, and sterilization technology. Ventilation and filtration provided by HVAC systems can reduce the airborne concentrates of SARS-CoV-2 and thus reduce the risk of transmission through the air.

Filtration: The fraction of particles removed from air passing through a filter is termed “filter efficiency,” and is provided by the minimum efficiency reporting value (MERV) under standard conditions. The American Society of Heating, Refrigeration and Air-conditioning Engineers (ASHRAE) defines the reporting value of MERV ratings in ASHRAE Standard 52.2 Method of Testing General Ventilation Air-Cleaning Devices for Removal Efficiency by Particle Size, and an excerpt from that standard is presented below to indicate performance characteristics and typical applications for each level of MERV rating. The HVAC in research facilities utilizes MERV 9 pre-filters and MERV 14 final filters. The HVAC in education and general spaces utilizes MERV 8 pre-filters and, in most cases, MERV 13 final filters. UES is currently upgrading these filters to MERV 9 and MERV 14, respectively, where equipment performance allows. These filter upgrades are occurring now and will be complete by the end of 2020. UCF will continue to adhere to the maintenance schedules and checkpoints as recommended in ASHRAE Standard 180 Standard Practice for Inspection and Maintenance of Commercial Building HVAC Systems for quarterly, semi-annual, and annual filter changes. All HVAC systems on campus are expected to receive at least one full quarterly preventative maintenance tune up this summer, which includes filter changes.

Ventilation: ASHRAE Standard 62.1 Ventilation for Acceptable Indoor Air Quality recommends a minimum air changes per hour (ACH) rate of two changes of outdoor air and at least two changes of total air as a general minimum ventilation requirement. Ventilation rates will vary from building-to-building, based on occupancy, and original design intent. UCF will continue to maintain design ventilation rates as determined by ASHRAE for air change rates, based on each building’s application. In buildings that have mixed use spaces (offices, classrooms, collaboration spaces), these spaces typically have 4-8 ACH of total air and at least 2 ACH of outside air exchanges per hour.

In research facilities, typical air change rates range from 6-18 ACH. For research spaces that are using laboratory ventilation systems serving fume hoods, snorkels, biosafety cabinets and other ventilated research equipment, those systems are served by 100% outside air units, so none of the air in those spaces is recirculated.

Administrative controls: UCF will seek adjusted occupancy rates in instructional and office spaces, to include 50% occupancy in areas with mobile furniture and 33% occupancy in areas with fixed seating. UCF is working with the Registrar’s Office on class start times and cleaning schedules and will update this section as the Fall Classroom Seating Task Force further refines the model for opening in Fall semester. Reduced occupancy will result in an increase in overall ventilation effectiveness per occupant, as the design ACH rates will remain in place or increase where possible, while the population in each building is anticipated to decrease.

Sterilization technology: In parallel, the university is also installing additional ultraviolet-bandwidth energy (UV-C) lighting in air handler units (AHUs) serving instructional and administrative offices. While data is limited on the effectiveness, of UV-C against COVID-19 specifically, in reducing the transmission risk within campus buildings’ HVAC air streams, the ultraviolet energy has demonstrated the ability to inactivate the DNA and RNA of most viral, bacterial, and fungal organisms so that they are unable to replicate. The kill rate for UV-C is based on a factor of time and exposure to the light. The UV-C systems being installed are designed to deactivate and mitigate flu virus particles with a single pass of the airstream in the AHUs. The flu virus is being used as a benchmark as it is a hardier virus strain that is harder to deactivate than COVID-19, so we are designing this deployment with an abundance of caution. Note that even with high-intensity UV-C irradiation, the deactivation rate will not be 100% for all biological particles.

The energy of ultraviolet light (UV-C) filtration is currently used in some air handlers on campus as it is effective in disrupting the reproductive DNA and RNA of infectious pathogens and helps maintain a clean and sterile environment inside the air handlers. Additional installation of UV-C has been prioritized for high-density instructional, administrative offices, and operational support buildings.

UV-C technology is currently being installed in select high-density instructional, administrative offices, and operational support buildings. AHU systems in research buildings that utilize mixed return and outside air (offices & classrooms) are slated for UV-C lighting.

Filtration media is an integral component of HVAC systems and is installed in all campus buildings. Greater filtration efficiency has been shown to reduce the risk of transmission. Facilities staff is evaluating individual equipment, and will install increased filtration, where possible.

Each building is equipped with a HVAC system that was designed specifically for its intended occupancy and space use, and therefore has capacity limitations based on the sizing and age of equipment to provide ventilation, temperature, and humidity control. UES is currently assessing and upgrading filters where equipment performance allows. These filter upgrades are occurring now and will be complete by the end of 2020. Increasing the MERV efficiency of the filter media may require, in some instances, a larger motor size and subsequently more energy to overcome the pressure drop created from the increased filter media to trap particulates. Therefore, many of the existing HVAC systems cannot handle filter upgrades without negatively impacting pressure and air flow in order to maintain the ventilation required for air exchange rates by design. Upgrading systems to increase airflow rates in many cases will require larger motors, prompting larger power wiring, breakers, transformers, electrical feeders, as well as larger cooling coils to maintain the leaving air psychrometric conditions needed to maintain IAQ, which may then require AHU frame sizes to be increased, larger chilled water pipes, larger chilled water pumps, and so forth.

The HVAC systems are cleaned and disinfected on a quarterly basis, as part of their normal preventive maintenance. This is done through a combination of antimicrobial fogging, UV-C disinfection, bi-polar ionization, electromagnetic filtration, and physical cleaning of the systems. All systems will receive their quarterly preventative maintenance and cleaning service prior to the start of Fall semester.

Indoor temperature design conditions range from 69 Deg. F. for heating to 74 Deg. F. for cooling, for general comfort to be in compliance with ASHRAE Standard 55 Thermal Comfort Conditions for Human Occupancy. As scientific literature reflects, relative humidity (RH) between 40-60% is the most unfavorable level for the survival of microorganisms; UCF adheres to this standard.

Due to Central Florida’s hot and humid climate, there are design limitations with HVAC systems and the amount of outside air that can be brought in and dehumidified for ventilation. These design limitations are based on the sizing and capacity of the air conditioning equipment’s ability to remove humidity from the air while providing positive pressure ventilation in each building to prevent unconditioned air from entering our buildings and to maintain indoor air quality to comply with ASHRAE standards. All university buildings are designed and operated to meet at a minimum the standards set forth in ASHRAE Standard 62.1.

Facilities and Business Operations staff actively participate in the ASHRAE Epidemic Task Force that develops global recommendations and guidance for industrial and commercial facilities. UCF will continue to monitor and implement OSHA, CDC, and other industry-related guidelines and best practices and adapt our administrative and engineering controls accordingly.