Sealing in Building Performance

Innovations Spark New Opportunities for Energy Savings

Tightening standards, expanding testing requirements and increasing client demand have contributed to an environment where energy savings, indoor air quality, and other building performance issues have become a critical consideration in both renovation and new construction projects. Fortunately for progressive contractors, the adoption of innovations and technological breakthroughs are providing new cost-effective opportunities for significantly improving building performance.

According to the U.S. Department of Energy (DOE), one of the greatest advancements in this area came out of research conducted at Lawrence Berkeley National Laboratory (LBNL), where scientists were challenged to find a viable solution to duct and ventilation leakage. A problem long understood, but typically ignored, duct leakage is estimated to cost Americans more than  $25 billion annually in wasted energy, and much more when the associated costs related poor indoor air quality and other factors are included in the calculations.

Traditional duct sealing in new construction is a labor-intensive, often ineffective procedure. Once the sections of ductwork are assembled and put into place, workers cover the connecting seams with mastic paste or specialized tape. Unfortunately, the ductwork is often difficult to access, and effectively sealing the seams can be challenging at best. Determining the success of the manual sealing process requires time-consuming testing of the duct system, a procedure that is habitually ignored in an effort to save time and expense.

As problematic as duct sealing is in new construction, it’s even more so in existing buildings. Few building owners are willing to approve the demolition required to access ductwork hidden behind walls and other structures. Once the ductwork is exposed, finding and sealing the leaks can be a contractor’s nightmare.

Given these obstacles, duct and ventilation leakage has been all but ignored for decades, and is now generally recognized as a leading cause of poor commercial building performance.

Enter the LBNL scientists.

Faced with the reality and impact of duct leakage, the DOE (along with the Environmental Protection Agency and other energy conservation-minded agencies) commissioned scientists at the LBNL to come up with a viable solution to the problem. The duct sealing solution had to be cost-effective, easy to implement, non-disruptive, safe for building tenants and, most importantly, effective at significantly reducing duct leakage.

Under the leadership of Dr. Mark Modera, then principle investigator for LBNL research, the team of scientists tackled and eventually found a solution by turning the sealing process inside out. Instead of accessing and sealing from outside the ductwork, it was surmised that easier access to the entire duct system could be attained via the duct interior. The ultimate solution involved the development and use of a “smart” aerosol spray that is blown into the interior of the duct system where it seeks out and seals leaks from the inside.

“The microscopic particles of sealant do not coat the duct interior, but rather stay suspended in the air until they come in contact with a leak,” Modera explains. “Driven under pressure where the only escape route is via leaks in the duct system, the sealant particles are propelled toward the leaks where they cling to the edges of the hole and then to other surrounding sealant particles forming a bond that quickly covers the entire leak.”

This inside/out approach not only alleviates the demolition typically needed to access the ductwork, but it also helps ensure that the entire duct system can be quickly and easily sealed tight the first time around. The computer-controlled delivery system provides the contractor with a visual model of the sealing process as it happens. A live graph showing the amount of remaining leakage allows the operator to determine when the sealing process is complete and eliminates the trial and error process of sealing, testing and then resealing. At the end of the sealing process, a printout report provides documentation of the before and after results.

The DOE has long understood that leakage in the air distribution system is a key contributor to energy waste and a significant factor when it comes to other building performance issues such as indoor air quality and tenant comfort.

Duct leakage is not only impactful, but it’s near ubiquitous as well. A recent BCA survey of building contractors reported that most industry professionals find leakage rates of 15 percent or more to be common in U.S. commercial buildings today. Three-quarters of respondents believe that the leakage is a major cause of energy waste in both new construction and existing buildings alike. And while the severity and pervasiveness of the problem is substantial, it highlights a great opportunity for savings and improvement.

With the development of aerosol-based sealing, the tide has begun to turn on duct leakage. During the past six years or so, hundreds of commercial buildings across the country (and the world) have solved previously unsolvable ventilation issues, energy waste concerns, poor indoor air quality and other factors directly related to duct leakage. From new high-rise apartment buildings struggling to pass building code, to medical facilities, universities, government buildings and office skyscrapers that were simply looking to improve HVAC and building performance, innovations in duct sealing are now making it possible.