Aeroseal Case Study — Cambridge Public Housing Complex

Public Housing Complex

With Excessive Duct Leakage Standing in the Way of LEED Certification for a New Public Housing Building, Aeroseal Succeeds Where Multiple Attempts at Mastic Failed


To be Leadership in Energy & Environmental Design (LEED) certified, the ductwork used to ventilate 40 bathrooms in the newly constructed five-story building had to demonstrate a total leakage rate below 250 CFM. With first test results showing 900+ CFM, it wasn’t even close. Not only were bragging rights to another energy-efficient building at stake, but so were thousands of dollars in federal rebate dollars that the Cambridge Housing Authority (CHA) planned on receiving through LEED certification.  

The mechanical contractor sent in a team of sealers to find and fix the leaks using traditional mastic sealing methods.
 After several costly attempts at manually sealing the ductwork, leakage rates remained much too high to meet building goals. That’s when the CHA decided to take a chance on Aeroseal, a new approach to duct sealing that works from the inside of the ductwork to find and seal the leaks.

Location: Cambridge, MA

Type: 5-story public housing complex

Goal: Meet LEED duct leakage rate of 250 CFM or less

Before Aeroseal: 900+ CFM of leakage

After Aeroseal: 40 CFM of leakage

Results: Reduced leakage by 95%

On a Friday, the Aeroseal team at Aspen Air Duct Cleaning set up their equipment and prepared the ductwork for Aerosealing. The following Monday they began and finished the entire project. The mechanical contractors retested the ductwork and confirmed what the computerized Aeroseal system reported upon completion of the process – Aerosealing the ductwork brought leakage down to 47 CFM – well below the LEED certification requirements. This total included the leakage around the fire damper door access panels. When the inherent leaks around these panels were taken out of the equation, the loss was only 8 CFM for the entire system.

The entire process took two workdays to complete and was conducted while other construction work continued throughout the building. Any concerns over health risks were quickly eliminated after a review of the technology’s Material Safety Data Sheets (MSDS) by the union steward. He found that the sealant was completely non-toxic and entirely safe. The CHA was so pleased with the results that it is currently in discussions with Aspen regarding the possibility of future Aerosealing projects. 

Initially, there was a lot of skepticism among the building engineers that Aeroseal would do the trick—especially when they leaned that the sealant doesn’t coat the entire inside of the ductwork but instead, accumulates around the individual leaks. After seeing the results, they are all now believers and big fans of the technology.”
— Bob Corsetti, Aspen Duct Cleaning

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

normi-logo nadca-logo


Hospital Undergoes Energy-Saving Retrofit
Without Disruption To Facility’s Daily Operations


A good ESCO is always on the lookout for new ways to save clients money.
Assessing operating budgets, reviewing overall building performance and
evaluating energy usage are just par for the course, as ongoing attempts are made to identify cost-saving options. And that means keeping abreast of innovations in building science that may lead to new energy-saving opportunities.

So when the manager of a large ESCO first sat down with Bobby Seals, Aeroseal’s director of national accounts, to discuss the energy-saving
strategies being implemented at a major New York State medical center, he had
already heard about Aeroseal technology and its unique approach to duct sealing. In fact, the company had already successfully used Aeroseal to seal ductwork and reduce energy waste during other building improvement projects, but this facility was a whole different ball game.


Aeroseal came to New York and did a preliminary analysis of the 100+ year-old medical center. The manager was aware that the hospital had air flow issues, and that indicated targets for potential energy savings. Now the question was how much savings would Aerosealing the ductwork provide and how viable would it be to do the work in a 24/7 hospital environment.
To ensure an accurate estimate would allow facility management to confidently forecast energy savings, Aeroseal used a proprietary modeling system that incorporates a number of extenuating factors (Figure 1). After a close and thorough inspection of the duct systems and sample static pressure testing, Aeroseal had the raw data they needed to make its calculations.

Building: Hospital / healthcare facility
Where: State of New York
Sealing Consultants: Aeroseal LLC
Objective: Reduce duct leakage for substantial energy savings
Before Leakage Rate: 29,836 CFM
After Leakage Rate: 870 CFM
Reduction: 28,966 CFM
Percentage: 97% reduction
Annual Savings: $22,694

“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


Armed with this detailed information, the facility manager approached the medical center’s administrators with a recommendation that they Aeroseal five separate duct systems within the facility. It was now up to Aeroseal to convince everyone involved that the work could be done with minimal interruption to the facility’s day-to-day operations.

“Energy savings is only part of the equation. We want to consider any project that will provide a sufficient return on investment, but before we commit to a project, we need to also consider its logistical ramifications. Clearly, the level of disruption or issues that may compromise the health or safety of our patients or staff can put an immediate halt to any project.”
– Facility Director

Over the course of several meetings, Aeroseal shared details about the Aerosealing process with both facility management and hospital staff. The hospital’s administrators reviewed MSDS documents that confirmed the innocuous nature of the sealant. They also reviewed a number of case studies that Aeroseal provided of other medical facilities where the Aeroseal technology was used. With their client’s approval to move forward, facility management gave Aeroseal the green light to proceed.

Over the next few months, the Aeroseal experts conducted research on the facility’s mechanical systems, constructed a plan of attack and consulted with hospital personnel.

Using Aeroseal technology to seal the ductwork had a number of significant advantages over traditional duct sealing methods. Applied as an aerosol mist, the sealant is blown into the interior of ductwork that has been temporarily segmented into specific sections.


Rather than coating the entire inside walls of the ducts, the sealant particles remain suspended in air until they are drawn to the various leaks. The particles then stick to the edge of the leak and then to other particles until the entire hole is completely filled from the inside.

One of the biggest advantages to this 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.

“Making sure everyone – from administrators, to doctors and other hospital staff were comfortable with what we were doing, was vital to ensuring everything went smoothly. Once everyone understood the process, a day-to-day schedule was developed.” – Aeroseal contractor

Hospital 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 imperative to the project’s success.

The sealing process itself took just fourteen days to complete. At the end of the project, 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) now down 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.


Aside from cost savings, the sealing process provided immediate improvements to the comfort level within the building. Doctors and other staff members commented on the positive change that the Aerosealing had on ventilation and temperature control.

Equally important to the success of the project, was the Aeroseal team’s ability to meet the highly individual needs of the medical center.

“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

nadca-logo   normi-logo