When it comes to air quality issues, the University of Ottawa Heart Institute (UOHI) has a zero-tolerance policy regarding air contamination. So, when an innocuous chemical isotope, produced in one of the institute's laboratories, was detected in an adjacent building, it was imperative the facility administrators find out how the chemical was apparently traveling from building to building and to stop its migration.
A thorough investigation of possible causes was conducted, and most initial theories were dispelled. At this point, the spotlight became focused on the Institute's ventilation system. While each laboratory building is vented separately, it was possible that leakage in the two air duct systems allowed contaminated air—and the offending isotope—to move from laboratory to laboratory.
"Given this scenario, we were looking at the daunting prospect of actually having to shut down all or part of the facilities and completely rebuild the ventilation system for the hospital," said Michelle Emond, project manager, UOHI. "Fortunately, one of our contractors told us about a duct sealing technology that does not require tearing down walls and ceilings to access the leaks in the ductwork."
Developed at Lawrence Berkeley National Laboratory with support from the U.S. Department of Energy, the duct sealing technology, now promoted as Aeroseal, works from inside the duct system to seal leaks. A delivery tube is connected to the ductwork—typically through either a temporary access hole or the exhaust vent on the roof—and the non-toxic sealant mist is fan-blown throughout the inside of the duct system. The microscopic particles of sealant remain suspended in air until they are drawn to the various holes and gaps throughout the ductwork. Once the particles reach a leak, they begin to accumulate around the hole, bonding to other sealant particles until the entire leak is sealed.
Because the sealant works from inside the duct system, all leaks can be sealed without having to tear down walls and ceilings to access the ductwork.
After passing the institute's stringent health and safety criteria, the sealant was used to seal one of several separate ventilation systems within the hospital. Once the sealing process began, the entire shaft was effectively sealed in less than a day, without interrupting the day-to-day operations of the facility.
With the ventilation shaft properly sealed, engineers were able to determine and fix the actual cause of the isotope leak. They also discovered and unanticipated benefit: sealing the ventilation shaft had dramatically improved the performance and energy efficiency of the hospital's ventilation system.
Emond said, "It turned out that prior to the application, we were losing about 800 cubic feet per minute (cfm) of ventilated air through duct leaks. That meant we had to run our exhaust fans at full power to get sufficient ventilation. The sealant reduced that air loss down to 10 cfm. We were able to turn down the power on the exhaust system while actually increasing ventilation efficiency. The difference was so significant, we are now looking at using this product elsewhere throughout the hospital to ensure proper ventilation and improve energy efficiency."
"The original ductwork was constructed of stainless steel that was welded together to minimize leaks," said Robert Seals, Aeroseal LLC. "But, as this project highlights, even high-quality installations can suffer from leaks that affect HVAC performance. A sealant product can fix the problem, usually with minimal if any disruption. "
To date, this approach has been used to increase the energy efficiency and performance of thousands of homes and commercial building throughout the U.S., including hospitals, laboratories, and university buildings.
Michelle Emond is project manager for the University of Ottawa Heart Institute where she has been employed for the past five years. Ms. Emond holds a degree in architectural engineering technology from the Saskatchewan Technical Institute and studied computer science at the University of Saskatchewan.
Robert Seals is the director of sales and marketing for the commercial division of Aeroseal LLC. He has more than 15 years of HVAC-related experience, including various positions with The Trane Company, Carrier Corporation, Bryant, and Siemens Industry, Inc. Mr. Seals holds a Bachelor of Science in pre-medical studies from Louisiana College, a Bachelor of Science in environmental engineering from Louisiana State University, and an MBA from the University of Phoenix.