Case in Point
Hospitals Cure High Duct Leakage with Sealing Technology
Owners of The Distillery North Apartments in south Boston are using energy-efficient, zoned HVAC systems, along with solar panels, to accomplish passive house standards, which looks to cut energy loads as much as possible and employ green power where possible. (Photo courtesy ICON architects/Photography by Camille Maren.)
Among its buildings, Miami Valley Hospital South in Centerville, Ohio, includes a 60,000-square-foot medical office building, a state-of-the-art cancer center, and a main hospital unit. During routine HVAC maintenance, the facility’s test and balancing (TAB) experts found that leaks, common throughout many of the duct systems employed on campus, were leading to significant HVAC performance inefficiencies.
With an ongoing mandate to reduce energy use, hospital administrators knew that by fixing the leaks, they could potentially save a substantial amount of energy.
The duct system serving the hospital’s six-story medical office building (MOB) presented the ideal opportunity for hospital administrators to try Aeroseal technology. Aeroseal is a duct-sealant technology that is applied from the inside of the duct system and was developed at Lawrence Berkeley National Laboratory in 1994. Research for Aeroseal technology was partially funded by the U.S. Department of Energy (DOE).
According to the Aeroseal representatives, the product is delivered as a nontoxic aerosol mist that seeks out and plugs leaks with 95 percent effectiveness. Officials said the new approach to duct sealing eliminates the disruptive processes involved in manually locating and sealing each individual leak.
“This approach offers a way to get to sections of the ductwork that you wouldn’t otherwise be able to reach,” said Larry Berna, facility operations manager at Miami Valley Hospital South. “It can also find and seal a lot of smaller leaks — leaks you wouldn’t otherwise find. A lot of small leaks multiply out to equal a big leak and potentially big energy savings.”
Technicians at the Ohio hospital took one day to Aeroseal the duct system. The facility’s TAB expert and its facility operations manager were on hand to watch the process and to view a graph depicting the leakage rate as the sealant did its job.
The final Aeroseal printout report for this single-duct system showed the leakage drop from the initial 1,673 cfm to 576 cfm. As a result, engineers were able to reduce the fan speed, saving 57,000 kWh. The hospital estimates annual savings of more than $5,000 with an ROI attainment in a little more than two years. After receiving similar results on a second trial project, hospital administrators are looking at other HVAC systems within the facilities that could benefit from Aeroseal duct sealing.
Sutter Solano Medical Center in Vallejo, California, also has had success with the Aeroseal system.
It was late on a Friday afternoon when Mark Avila, president of Air Seal Solutions, San Jose, California, got a call from a distraught mechanical contractor. The engineer’s team had been working for weeks on a new ventilation system that Sutter Solano Medical Center had installed to exhaust air from the hospital’s new autoclave sterilization room. No matter how many times they went at it, they couldn’t get the ducts sealed tight enough to draw sufficient air through the system — or to pass local OSHPD code.
And now, with walls hiding the ductwork and limited space between the newly installed duct and the ceiling, several subsequent efforts at resealing proved increasingly futile. Worst of all, final inspection was scheduled for the following Monday, so the contractor had to have the system up and running properly by the end of the weekend.
With no time to waste, Avila explained the Aeroseal process to the contractor and arrangements were made for the Air Seal Solutions team to begin work the following day. They arrived at 8 a.m. Saturday morning and went to work. First, they temporarily blocked the effected registers and the ductwork just short of the autoclave machine. They then removed the system’s rooftop fan and connected the Aeroseal equipment to the top of the exhaust duct. With a flip of a switch on their computerized duct-sealing system, the leakage rate measured 650 cfm, which was about 50 percent of the total system output.
With another flip of the switch, Avila’s team began the sealing process, blowing microscopic particles of sealant into the interior of the ductwork, where they automatically sought out and sealed the tiny holes that riddled the system. By 3 p.m. that afternoon, the ductwork was completely sealed. Readings showed there was now less than 1 percent of leakage.
“The technology is really quite amazing,” said Ron Lynch, project manager at Superior Mechanical Services, Livermore, California. “Because of how the existing duct was sandwiched into the ceiling along with pipes and electric conduits, there was simply no room to manually seal. But the hospital didn’t want to hear that there was a problem — they wanted results; results we couldn’t achieve. Then, with the Aeroseal technology, the problem simply went away. It really saved our backside. Aeroseal was able to do in a single afternoon what we couldn’t accomplish in weeks of manual sealing and resealing.”
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