Much of what drives the efficiency of a high-performance building is the resilience of the HVAC system. It’s that system largely responsible for keeping indoor conditions comfortable, blocking out contaminants and producing energy savings.
Ideally, that’s the design. It doesn’t always work that way, though.
Despite the seemingly higher efficiency and overall effectiveness of many of today’s HVAC systems, conditioned air still often manages to seep out, causing the HVAC to work harder, minimizing efficiency.
The culprit: Leaky air ducts.
And what’s worse, fixing the problem can mean ripping down walls and spending gobs of money to gain access and make repairs.
“Most people don’t even think about the role that ductwork plays in commercial building performance,” said Neal Walsh, senior vice president of Aeroseal.
But they do see it as a problem.
A recent survey from the Building Commissioning Association (BCA) found that most engineers and other building professionals – 75 percent – believe duct leakage is a significant cause of energy loss in commercial buildings. The portion of the report dubbed “The Hole Truth” also showed that some 22 percent of respondents indicated that leakage was evident in both new and existing structures.
Though the study highlights “beliefs,” additional research shows that perception is reality.
The U.S. Environmental Protection Agency and U.S. Department of Energy both call duct leaks main contributors to inefficient buildings. The Energy Department estimates that more than $5 billion in energy is wasted annually through air duct leakage.
There are numerous triggers of leaky ducts, Walsh said. Among them:
- Poor sealing during installation
- Movement over time
- Damage during other building construction or renovation
- Deterioration to the tape or mastic originally used as seals
Regardless of the reason, the challenge facing building owners and operators is how best to plug those leaks with the least physical or financial disturbance. Too often, the problem is simply ignored, Walsh said.
While a number resort to major facility rework, some focus on other sustainability strategies that work to offset those leaks.
Officials with the Energy Department and EPA, meanwhile, rank duct sealing among the most effective strategies in making facilities more efficient. They even back products like aeroseal, an aerosol-based duct sealing technology developed in 1994 by DOE’s Lawrence Berkeley National Laboratory through research funded by the department, EPA, Electric Power Research Institute and California Institute of Energy and Environment.
In fact, aeroseal is considered among a handful of the most important home energy conservation technologies ever developed by the Department of Energy, according to the Lawrence Berkeley lab. Such an approach is seen as twice as effective at reducing energy usage as upgrading heating equipment and nearly five times more effective than upgrading windows, finds research firm McKinsey and Co.
The Aeroseal process entails pumping an aerosol sealant solution through a building’s ductwork, which builds up only in gaps to plug leaks. The computerized application process shows installers the leakage rate while sealant is being forced through the duct system.
Though originally developed for the residential market, the product’s success – it saves homeowners as much as 40 percent on monthly energy bills, and a single application is expected to last the life of a home – quickly garnered attention within the commercial building field, officials say.
In recent years, it’s been used everywhere – both in new construction and in retrofits – from universities to hospitals to industrial plants.
Engineers get schooled
When Dr. Philip Wagner, the superintendent at Ohio’s Licking Heights school district, looked at the cost for heating and cooling all five of its school buildings, a 7-year-old elementary school stood out, as its energy bills were double that of a similar school nearby.
Uneven heating plagued the structure. To keep warm, students and teachers in the far wing of the building often wore hats and coats during class.
An energy audit revealed that each school in the district was losing about 30 percent or more of treated air through leaks in the ductwork. West Elementary School, however, was losing more than 50 percent of treated air through duct leaks.
The district considered several options to fix the problem but in the end, due to lower cost, limited disruption and a strong guarantee, it opted for aerosealing.
The project was done over a winter holiday break. And when teachers and students returned after the New Year, they returned to a different environment – all of the classrooms were warm and comfortable.
Thermostats were turned down. Fan power was reduced.
With the ductwork effectively sealed, the school district estimates that it will save about $45,000 each year on its utility costs. On top of that, the district received a $27,000 energy savings rebate from the local utility company.
“I am always skeptical about claims that sound too good to be true, so when I first heard about aeroseal, it was originally, in my mind, the least appealing option,” Wagner said. “But after doing some research and learning about its use at other education facilities … it quickly became the solution of choice.”
Aeroseal was met with considerable skepticism upon its release, fueled mostly by disbelief that a product could work fast and easily, Walsh said. In fact, one engineer with whom the company assisted, secretly punched some small holes in ductwork before his system was aerosealed.
“He was shocked to find that those holes were sealed just minutes after the process commenced,” Walsh said. “As success stories continue to mount, the word is spreading and the technology’s adoption is gaining momentum. … Engineers are learning that it may be cost-effective and more productive to simply aeroseal a duct system from the start and eliminate manual sealing methods altogether.”
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