In a recent Jeffco School Board study session, board members heard a presentation on the results of an indoor air quality pilot program.

Toward the end of the presentation, Kimber Preece, a District Sustainability Engineer, said the Facilities Department recommended Ultraviolet Germicidal Irradiation (UVGI) system implementations across the district as well as increased outdoor ventilation and filter efficiency.

Preece handled most of the presentation for the district. But before she got underway, Susan Harmon, Board of Education President, gave a bit of background information on the pilot program.

“Since the second quarter of 2020, the Facilities and Maintenance Department has made a significant effort to improve the indoor air quality of our facilities,” she said. “These improvements align with industry and health care recommendations. We have also looked at options that would result in air quality improvements beyond the pandemic.”

Pilot Program

A pilot program was implemented in which UVGI were installed in all six air handling units at Governors Ranch Elementary over the ’20-’21 holiday break. The district then started taking air quality measurements at Governors Ranch as well as Ute Meadows and Stony Creek Elementary Schools.

According to Preece, those sites were chosen because they have the same floor plans and the same type of HVAC equipment. 

They then used special equipment called AGAR plates to collect bacterial samples. Those plates were then sent to a lab for analysis to see if the bacteria create colony forming units (CFUs).

Each day of testing, the district took 3 measurements at each site — three interior samples and one exterior sample.

The study concluded that the district’s design and installation procedures had been done correctly, because when compared, the levels of CFUs were higher in interior samples taken from Stony Creek and Ute Meadows than samples taken at Governors Ranch.

The district also wanted to know if the systems would be a good value and be usable in a post-COVID future, for lowering levels of influenza and rhinovirus. So, it compared the cost and effectiveness of the UVGI technology to decentralized HEPA units in classrooms.

The science

Preece said humans emit around 85 watts (of heat) while sitting.

She then showed a video example of smoke displacement to give board members an understanding of the way air moves through a room. 

In the video, smoke enters a room through a typical duct vent near the floor. As the smoke (or air) moves through the room it gravitates toward the heat generated by human bodies. The smoke (air) then moves up the person’s body toward the ceiling in a thermal plume. Preece said when viruses are present, there are viral plumes within the thermal plumes. 

As the plume rises to the level where one breathes, the video communicates in a clear way, how the placement, design and implementation of air filtration systems are important.

Preece said both ASHRAE (American Society of Heating, Refrigeration and Air-Cooling Engineers) and the EPA (Environmental Protection Agency) have given guidance on how to place in-room disinfection units and fans in order to prevent the creation of drafts across occupants, which can create unhealthy breathing conditions.

In other words, both ASHRAE and the EPA stress the importance of creating systems where air does not flow from one person onto another, to reduce the spread of droplets that may contain infectious viruses. 

“As you can imagine, in a very full classroom it’s hard to put something in a room and not create a draft across the many occupants that are in that room,” she said. “I hope you also noticed in the video, social distancing and mask wearing are important because those thermal plumes can help get those pathogens away if we trap our projections with our masks.”

Preece said HVAC systems the District already has in place in schools, work with 5-12 changes (air exchanges) per hour, which is magnitudes higher than any other system they could place inside classrooms. Another benefit of the current HVAC systems is that they don’t create drafts.

What’s next

The District is currently installing the system at Everitt Middle School to see results from a larger school. They have started collecting untreated air quality data as a baseline for the Everett study. 

When it comes to costs, Preece said district-wide implementation of UVGI has a higher initial price tag, but the HEPA filter operational cost is so great that within a year, UVGI becomes the financially responsible choice. Maintenance costs of UVGI are also lower. UVGI also filters the air quicker and they’re quieter and longer-lasting than HEPA units, she said.

Preece said better indoor air quality increases performance and attendance, reduces the load on support staff during a pandemic and also extends the possibility of in-person learning.

The cost of installing a UVGI system in an elementary school is $33,000. Bell said he believes federal ESSER funds (Elementary and Secondary School Emergency Relief) can be used to pay for UVGI system implementation (but there was no final determination of that during the study session).

Bell said the estimated cost of a district-wide implementation was $8.5 million.

Board President, Susan Harmon said the research feels like the right work in terms of creating healthy environments for students to thrive — as well as being the right thing for staff, teachers and food service workers.

“I don’t think we’re a guinea pig. I think we’re a leader,” she said. “And this is the right work to be leading our district instead of waiting.”

Harmon said she is looking forward to hearing more about the Everitt study as it progresses, during upcoming board meetings.