Public schools play an important role in the communities they serve. More than just a place for students to learn, schools offer valuable extracurricular programs for young people and their families. They help foster a connection between the students and the world around them, and the best schools continually rise to the needs of their neighbors. That was the case in Minneapolis, MN, when Ella Baker Global Studies and Humanities Magnet School (formerly Jefferson Middle School) realized its HVAC system was causing too much noise.
Ella Baker School sits in the middle of a dense suburban neighborhood. The multistory building was built close to the street, directly across from houses and apartments. When the school first learned that its mechanical equipment ran too loud in early 2020, it promptly acted on it.
| Ella Baker School is located in a dense suburban neighborhood and, since installing the new Noise Control solution around its mechanical equipment, is a much quieter fixture in its community |
One proposed solution involved changing the system’s start and stop times, but this would require the school to maintain a higher overnight temperature, which would significantly increase its energy usage and operating costs. The school also considered installing more mechanical equipment to support the existing unit, but the added weight would have required structural work on the building. Instead, the staff of Ella Baker School opted to find a more permanent solution.
In July 2020, a report commissioned by the school found that the mechanical equipment noise peaked at 98.5 decibels (dBC) under a full load – louder than a running lawn mower. The report also found the visibility screen was ineffective at absorbing sound, which measured 17 dBC above the average ambient level at the line of sight. The report recommended the existing screen be upgraded to include sound-dampening properties able to reduce the noise to within an acceptable range.
When Mike Lind, Engineering Manager at TMS Johnson, brought news of the project to Price in 2021, the Noise Control team immediately began to devise a solution. Working closely with Leo A Daly, the architectural firm assigned to the project, and using the Price Acoustic Analysis software to optimize the design, the sound engineers at Price proposed that bespoke acoustical barriers be installed at key points around the unit. Able to guarantee a significant noise reduction without the need for new mechanical equipment or renovations, Price Noise Control offered exactly the practical solution the school had hoped to find, and it moved quickly to approve the project.
| The project team in front of the school’s custom-made enclosure |
With the Price Noise Control team now involved, work on the school’s rooftop began in earnest. A solid, noise-dampening wall was erected at a 4-foot distance from the HVAC unit on all sides. This was followed by multiple absorptive 4-inch-thick panels installed inside the supply and return fans, and a silencer at the condensing unit.
When the jobsite wrapped in June 2022, the custom-made enclosures delivered stunning results: an apples-to-apples comparison of street-level noise measured with the mechanical unit at full load revealed the new sound-dampening structures mitigated the noise differential to a mere 5 dBC. In practical terms, these enclosures reduced the sound by more than 50%, as a 10 dB reduction is perceived as half as loud to the human ear – a dramatic improvement over the initial measurements.
| Mauricio Salinas, Price’s Application Engineering Manager for Noise Control, takes a noise reading outside the new acoustical enclosure |
Best of all, since completing the acoustical treatment on the rooftop, the school is no longer a noisy neighbor. Having restored quiet to its cozy Minneapolis neighborhood, Ella Baker School has proved to be a true steward of its community.
For more information about our noise control solutions, visit our website or reach out to us at noisecontrol@priceindustries.com.