Searing heat in Minnesota is forcing school districts — already concerned about indoor air quality amid the pandemic — to consider further mechanical upgrades to buildings without air conditioning.

The temperature topped 100 degrees in at least one Minneapolis classroom in June before the district shifted students in 15 buildings without air conditioning to distance learning. Bloomington schools brought in portable air conditioning units to keep kids cool. St. Paul called off school altogether, ending the year a few days early.

The disruption further highlighted how the mechanical systems within school buildings play a key role in providing a safe learning environment for students. The topic had already gained fresh attention during the pandemic, as schools rethought ventilation and air filtration to prevent the potential spread of COVID-19. Now, as districts make their plans to spend another wave of federal money from the American Rescue Plan, the systems upgrades may get pushed ahead.

"COVID was and is extremely difficult, but in the end, I am excited for the opportunities that may come out of it," said Angela Vreeland, the indoor air quality coordinator for St. Paul Public Schools. "People are now so much more aware of indoor air quality and the importance of ventilation and filtration. We have an opportunity if we can use additional funding to make improvements."

Before students returned to in-person classes, St. Paul increased the level of filtration in its buildings, a longstanding goal that became a priority during the pandemic, said Tom Parent, director of facilities.

About one-third of the district's buildings are air-conditioned after a push over the last five years to add cooling systems to about 1 million of the 7.3 million square feet of school buildings. Four schools in the district have HVAC (heating, ventilation, air conditioning) upgrade projects underway, and seven additional schools have been identified as needing them, Parent said. The timeline for that work could be moved up if the district decides to use federal money to pay for it.

"We're fairly aggressively adding AC and humidity control into our buildings," Parent said, adding that the district is examining how to handle rising temperatures and extreme weather.

The discussions depend on the age of the buildings and the options available. The St. Paul district has buildings of many ages, including one that dates to 1890. Old doesn't inherently mean bad, Parent said, but upgrades aren't one-size-fits-all.

Minneapolis' oldest school was also built in the 1890s. In a statement, Minneapolis Public Schools operations staff said a building's age can make the addition of air conditioning "a complex and expensive task." The district has 11 buildings without air conditioning and four with partial systems. It's developing estimates, expected by Sept. 1, on what it would cost to install it in all schools.

The pandemic has already "changed the overall air filtration system strategy," the statement said, prompting the district to complete reviews of each building's ventilation systems and add portable HEPA filtration units in areas that couldn't otherwise be served by upgraded air filtration systems.

"We will continue to provide increased filtration and ventilation while the pandemic is still a concern for students, families and staff," the statement read.

The Minneapolis teachers union has included air conditioning on its list of priorities as the district makes plans for the latest wave of federal relief funds.

"Now we really have an opportunity to make these changes," said Greta Callahan, the president of the Minneapolis Federation of Teachers.

For Bruce Bomier, board chairman of the Environmental Resource Council, an Andover-based nonprofit that advises schools on environmental health, having air conditioning is "low-hanging fruit" for districts looking to support students who need to make up for lost learning.

"Then schools have better options for teaching in the summer," he said.

Both Minneapolis and St. Paul host their summer programming in air-conditioned schools.

About 70% of Bloomington's elementary schools and one of its middle schools had undergone mechanical systems upgrades before the pandemic. In addition to providing additional filtration over the past year, the district brought in portable air conditioning units for three buildings this spring and may bring them back in the fall.

"The heat combined with having to wear masks and everything else these students and teachers have been through ... we just wanted to provide relief," said Tim Rybak, the director of operations for the district.

The pandemic hasn't accelerated the timeline to add air conditioning to Bloomington schools, but it "very well could," Rybak said.

Even some small school districts have focused on replacing air filters and improving air flow in their buildings, said Glenn Morris, the director of the Minnesota South Central Service Cooperative, which provides engineering support to schools in central Minnesota. He said many districts are expressing concern about the ongoing expense of the upgrades.

The pandemic accentuated several issues in education, Rybak said, and raised conversations about schools' mechanical systems.

"One of the positives of the pandemic for some districts," he said, "is this ability to focus on areas that may not have received funding or attention otherwise."

Mara Klecker • 612-673-4440