Game-Changing Study Finds Aeroseal a Cost-Effective Solution for Duct Leakage in Commercial Buildings


Historically, duct leakage has often been viewed as a performance issue rather than an energy efficiency issue. Not anymore! As noted in a recent Building Solutions blog post, duct leakage is actually the Number 1 culprit when it comes to energy waste in commercial buildings. The growing recognition of duct leakage as a major cause of HVAC energy waste provided the impetus for a study on retrofit duct sealing conducted by the Center for Energy Efficiency (CEE) in Minnesota.


This four-year study and pilot project had several phases, beginning with the characterization and measurement of duct leakage in several types of Minnesota commercial and institutional (C&I) buildings. In the next phase, a subset of the C&I duct systems were sealed using both conventional and aerosol sealing methods. Finally the estimated energy savings and cost effectiveness of retrofit sealing measures were analyzed in order to develop screening criteria to identify cost-effective duct sealing opportunities.

The recently released study findings confirm that duct leakage in existing buildings has emerged as a new energy savings opportunity.  In fact, about 10% to 15% of Minnesota C&I buildings were found to have appropriate operational characteristics and leakage rates that are high enough to justify retrofit duct sealing work with a moderate to good payback of less than 7 years. In addition, the study found that duct sealing from the inside using the aerosol sealing method was effective in a variety of scenarios, often reducing leakage effectively to zero including:

  • Initially tight and leaky ductwork
  • Supply and exhaust ductwork
  • Upstream and downstream ductwork

The Center for Energy and Environment conducts technology and market assessments to identify tomorrow’s best clean energy strategies. This retrofit duct leakage study was conducted for the benefit of Minnesota’s Conservation Improvement Program (CIP) with funding from the Department of Commerce, Division of Energy Resources.

Source: Aeroseal

Aspen Air Duct Cleaning is an approved Aeroseal Dealer, licensed and ensured, and a member of the National Air Duct Cleaners Association (NADCA) and National Organization of Remediators and Mold Inspectors (NORMI).

Please contact Aspen Air Duct Cleaning at 1-800-931-6653 for an Air Duct System Inspection and to learn more about how sealing air duct leaks can improve indoor air quality and reduce energy costs. Or email

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Medical Center Saves Significant “Green” by Addressing Top Commercial Building Fault


Mom always scolded us not to leave the refrigerator door open (or we’d let all the cold out AND raise our electric bill). And everyone knows you should turn off the lights before you leave a room to save energy. But let’s magnify little house-based issues to the larger scope of commercial buildings. What do you think the top commercial building fault when it comes to energy waste/loss?  The answer is clear: Duct Leakage.

Berkeley National Labs did a study of the Top Ten building faults by cost (Figure 1), and the faults you would expect are on the list – the lights and HVAC left on when the building is unoccupied, not balanced airflow, dampers not working, etc. However, duct leakage tops the list, with an estimated annual cost of over $2.9 billion per year (which is 53% more than the second most expensive fault).

Figure 1

Figure 1 – Source: Building Commissioning: A Golden Case for Reducing Energy Costs, E Mills, 7/09

Duct Leakage Low-hanging Fruit for ESCOs
A good Energy Services Company (ESCO) is always on the lookout for new ways to save clients’ money. They have lots of choices when it comes to sustainability and energy conservation measures (ECMs). Assessing operating budgets, reviewing overall building performance and evaluating energy usage are just a few. As seen in Figure 1, duct leakage is the “low-hanging fruit” with the biggest, and quickest opportunity for payback.
That’s what was discovered recently at New York State medical center. Aeroseal came to the center and conducted a preliminary analysis of the 100+ year-old facility. The facility manager was aware the hospital had air flow issues, and thus the potential for significant energy savings. The question was how much savings would Aerosealing provide, and how viable would it be to do the work in a 24/7 hospital environment?

Luckily both of these questions were answered affirmatively… and the results were nothing short of astonishing.

Armed with an Energy Model and a Plan
After a close and thorough inspection of the duct systems and sample static pressure testing, the Aeroseal team had the raw data it needed to make its savings calculations and return on investment estimations using a proprietary energy model. (Figure 2)

Figure 2
Figure 2 – Return on Investment graph

“The veracity of Aeroseal’s energy model and the leakage rates they were able to obtain through computerized testing gave us confidence that the estimated savings would be on target. Watching the process, we felt it was less about typical guesswork as it was about experienced testing and extrapolations – and it was backed up with a guarantee that we would get the level of ROI estimated by the final calculations” (ESCO/facility management).

But estimated energy savings was only half the battle. The duct sealing work also had to be performed safely with little to no disruption to the hospital’s day-to-day operations. After reviewing the patented Aeroseal process, including safety, longevity, results, and impact on their operations, hospital administrators gave the green light. The Aeroseal team constructed a plan of attack for the sealing five separate duct systems, and they consulted with hospital personnel every step along the way.

Staff from each unit involved knew when and where the work was taking place well in advance of any activity. They received continual updates throughout the project and were kept abreast of any new developments that might have arisen. Effective and ongoing communication with the administration and the facility managers as well as the staff was key to the project’s success.

Another big advantage to the Aeroseal approach is that it makes the entire duct system easy to access. Sealing from the inside-out eliminates the need to tear down walls, expose ceilings or tear off insulation in order to access the leaks. Not only does this account for the highly effective nature of Aerosealing when compared to tape or mastic, but it also eliminates the majority of disruptions associated with traditional duct sealing activity. In the hospital environment, minimizing the risks associated with such structural demolition was key.

The Results Are In!
When the project was complete, Aeroseal provided facility management with a detailed report of the results. Data taken before, during and after the sealing project showed an original leakage rate of 29,836 CFM (cubic feet per minute), which was reduced to a low 870 CFM. This represented a 97% reduction – 4% more than the originally modeled estimate. Based upon the report provided by Aeroseal, the facility manager was able to show his clients an annual cost savings of $22,694, based upon reduced air loss and lower fan speeds. Payback for the project would be well under seven years.

In addition, the sealing process provided immediate improvements to the comfort level within the hospital. Doctors and other staff members commented on the positive change that the Aerosealing had on ventilation and temperature control.

“There were two primary things that made this project such a success. First, flexibility. The Aeroseal team knew they couldn’t just come in and shut down equipment or section off the hospital to get their work done. Second, was planning. The preparation put into this project before the sealing even began was extraordinary and reflected the team’s understanding of the special requirements demanded by this unique environment. All of the advantages of the technology itself, implemented by a team that understood and met the unique requirements of a hospital environment made this a tremendous success.” – ESCO/Facility director

Source: Aeroseal

Aspen Air Duct Cleaning is an approved Aeroseal Dealer, licensed and ensured, and a member of the National Air Duct Cleaners Association (NADCA) and National Organization of Remediators and Mold Inspectors (NORMI).

Please contact Aspen Air Duct Cleaning at 1-800-931-6653 for an Air Duct System Inspection and to learn more about how sealing air duct leaks can improve indoor air quality and reduce energy costs. Or email

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