Schools and universities seeking to make their facilities healthful learning environments that help combat the spread of Covid-19 should focus on their heating, ventilation and air conditioning (HVAC) systems—specifically the ventilation part.
“HVAC systems are critical to Covid-19 mitigation efforts due to their ability to control airborne pollutants and viruses and to distribute fresh outside air in classrooms,” the Learning Policy Institute says in a December 2020 paper.
The systems may be critical in the fight against Covid, but too many of them may not be up to the task. The obstacle for thousands of schools is the condition of their HVAC systems. Education institutions in general struggle with facility maintenance backlogs—problems that have been ignored or deferred because of inadequate funding and the priority given to more urgent crises. Keeping HVAC systems in shape is one of those items that get put on the back burner.
A June 2020 study by the Government Accountability Office (GAO) found that an estimated 41% of school districts need to update or replace the HVAC systems in at least half of their schools. That equates to about 36,000 schools.
“If not addressed, HVAC issues can result in health and safety problems,” the GAO says.
Covid-19 is a health and safety problem that descended into all schools whether or not their facilities had HVAC issues, but adjusting and upgrading HVAC systems to combat the virus will help schools provide a safer and more healthful learning environment for students.
The Covid relief package enacted by Congress in March allocates $130 billion in aid to K-12 schools, and some local districts may opt to use some of that to improve or replace their HVAC systems. But improving HVAC systems in all the facilities that need it will be costly.
The Learning Policy Institute estimates that the cost for new HVAC systems ranges between $30 and $50 per square foot.
“If half of the 36,000 buildings with sub-standard HVAC systems require upgrades and the remaining 50% require new ventilation systems, it would cost approximately $72 billion to ensure safe and healthy air quality in all schools and classrooms,” the institute says.
Healthy venting
For months, many classrooms sat empty because of the coronavirus, and concerns about HVAC systems and indoor air quality took a back seat to the effort to pivot to online instruction and make sure that students still could keep learning via the internet.
Now, as more school facilities are cleared to welcome students back from their pandemic-imposed exile, maintenance and operations staff should turn their attention to providing healthful learning spaces.
The Council of the Great City Schools is one of several organizations to provide guidance to help schools improve the air quality inside classrooms and other spaces.
“Improving air quality and increasing ventilation in our school buildings is one of the most important steps districts need to take to prepare school facilities for the return of students, teachers and staff during the Covid-19 crisis,” the Council says.
The Council has compiled recommendations to help schools maintain their ventilation systems to improve indoor air quality and lower the potential for Covid-19 circulating in a school building. Among them:
•Better filters. Return air filters in HVAC systems should be changed to those that have higher efficiency and trap more particles—the Council recommends a minimum MERV 13 filter (or equivalent) with the greatest depth allowed by the equipment, typically 2 inches where possible.
•Daily air flush out. Before teachers and staff arrive in the morning, maintenance workers should have the control settings and schedules for the ventilation systems and fans set so that they run for a minimum of two hours in occupied mode with the peak outside air rate.
•Open Windows. In facilities where there is no central HVAC system, doors and windows should be opened two hours before occupancy and at other times throughout the day.
•Regular inspections. Schools should conduct regularly scheduled preventive maintenance inspections on HVAC systems to ensure they are operating properly and providing adequate ventilation.
The U.S. Department of Education’s Covid-19 Handbook, released in February, encourages schools to develop a ventilation improvement plan for their facilities.
“For example, districts and schools can schedule incremental checkpoints to ensure plans for updating ventilation are going according to schedule and increase the frequency of changing ventilation filters,” the handbook says
The Centers for Disease Control and Prevention (CDC) provides additional recommendations to ensure that HVAC systems in schools are maximizing ventilation.
•Set HVAC systems to bring in as much outdoor air as a system will safely allow.
•Disable demand-controlled ventilation controls that reduce air supply based on occupancy or temperature. Doing this will keep the air supply constant throughout the day.
•For simple HVAC systems controlled by a thermostat, setting the fan control switch from “auto” to “on” will ensure that the HVAC system provides continuous air filtration and distribution.
•To enhance the effectiveness of open windows, use fans.
“Fan placement is important and will vary based on room configuration,” the CDC says. “Avoid placing fans in a way that could potentially cause contaminated air to flow directly from one person to another.”
If schools are opening windows and using fans, they should take safety precautions, such as using fans with covers and having screens on windows.
•Consider portable high-efficiency particulate air (HEPA) fan and filtration systems to enhance air cleaning (especially in higher-risk areas such as a nurse’s office or areas frequently inhabited by people with a higher likelihood of having Covid-19).
•Ventilation is especially important in areas where students may not be able to wear masks; if students have to eat indoors in a cafeteria, use methods such as opening windows, maximizing filtration as much as a system will allow, and using portable HEPA air cleaners.
•Make sure air filters are properly sized and within their recommended service life.
•Generate clean-to-less-clean air movement by evaluating and repositioning as necessary, supply louvers, exhaust air grilles, and damper settings.
•Consider using ultraviolet germicidal irradiation as a supplemental treatment to inactivate Covid-19, especially if options for increasing room ventilation and filtration are limited.
