Green ductwork.

While the term lacks a conclusive definition, it’s certainly emerged as an industry buzzword. Depending on who you’re talking with, the phrase can mean different things, though most agree it typically encompasses recycled materials, various IAQ elements, duct-sealing products, and more.


Many elements can help make ductwork green, said Nick Kaufmann, director of manufacturing and engineering, DuctSox Corp.

“First of all, ductwork can be made out of recycled content,” Kaufmann said. “DuctSox has fabric ductwork available that is 55 percent recycled polyester, which is a desirable option when seeking LEED [Leadership in Energy and Environmental Design] points.

“Fabric ductwork is lightweight. It’s typically about 90 percent lighter than metal ductwork of the same size and diameter,” continued Kaufmann. “The larger the facility, the more structure is needed to support the ductwork. By using fabric ductwork, there is less need for roof support and tether supports to hang it, so you’re really using fewer materials and resources overall. There is less solid waste.”

Another advantage to using DuctSox fabric ductwork is that it uses linear dispersion, which helps eliminate hot spots or cold spots.

A study conducted at Iowa State University confirmed that linear dispersion, which is used in DuctSox, can bring an area up to temperature very quickly. Additionally, fabric duct is easy to install, which saves contractors in labor and shortens downtime for end users. These are big factors in mission-critical applications, such as data centers.

When it comes to a contractor trying to sell a concept to an owner, time is money, Kaufmann noted. “Data center managers are concerned with energy usage, and DataSox effectively increases energy efficiency.”

DataSox distributes large amounts of air down data center cold aisles, but with low 400-feet-per-minute (FPM) velocities that do not upset critical equipment intake and exhaust or room return air-containment balances. It also offers the flexibility of directional spot-cooling capabilities with adjustable nozzles for high-wattage servers. The nozzles, combined with specialized porosity and interior air adjustment, allow for on-site testing and air balancing for optimum performance. DataSox features factory-engineered, energy-efficient ¼- to ½-inch water gauge of static pressure and a 3°-5°F lower temperature delivery due to low entrainment from the surrounding aisles. When utilized with variable frequency drive (VFD) equipment, DataSox features low computer room air conditioning (CRAC) flow rates and helps data centers achieve lower power usage effectiveness (PUE) levels.

Another important LEED aspect is acoustical performance. DuctSox can deliver air quietly, and the material is fabric, so it does not reflect sound in a space like traditional metal does. The SkeleCore frame stops any inflation noise and now has a DuctSox fabric sound attenuator available.


When it comes to explaining green ductwork, Tim Ledden, technical manager, insulation, Armacell LLC, defines it as simply supplying the cleanest air to the building occupant.

“It’s generally people trying to remove contaminants from the airstream and live healthier,” Ledden said. “Many of the chemicals in some of these insulation products and in the ducts themselves are making people sick. Some can be linked to illnesses, and, with others, we don’t really know if there is a link yet. People are definitely concerned. There is a growing consumer awareness of all the VOCs [volatile organic compounds] involved in different products.

“Insulation plays a large role because many ducts are lined with it — especially for noise reduction,” he continued. “So, insulation is in direct contact with the airstream that is going into buildings. If there are any contaminants, off-gassing, or VOCs within the insulation itself, they’re directly put into the building because there’s no filter between these items and the air coming into the actual building.”

Armacell’s AP Armaflex duct liner is fiber-free and Greenguard Gold-certified, Ledden noted. “It limits VOCs far below any existing IAQ requirements. It also protects against condensation and reduces the possibility of mold or any other bacteria or microbial growth on the insulation. It’s also easy to clean, which eliminates dust and other contaminants.”


Perhaps the most common interpretation of what makes ductwork green is increased efficiency resulting from properly sealed duct leakage.

“When people talk about green ductwork, they’re really talking about making it tighter and more efficient, so it has less leakage,” said Steve Ulm, director of marketing, Semco LLC. “If you have less leakage, you’re using less power, which means you’re creating a greener environment because you’re putting out fewer emissions. That’s where the green aspect comes from.”

According to Ulm, government energy initiatives and standards are driving the green ductwork trend.

“They’re looking to become as efficient as possible to reduce costs and, ultimately, reduce energy consumption,” he said. “When you look at duct, traditionally, there have been two kinds, round or spiral round, which is what we do, and rectangular. And, in the past, rectangular duct could potentially leak anywhere from 30-40 percent. Newer rectangular duct construction has gotten much better, but there is often still leakage. You still have to take the time to seal it to make it more efficient. Meanwhile spiral round, in and of itself, meets specification because it goes in as one individual piece with less than 1 percent leakage. Because it’s a mechanical closure, you don’t have to use sealants. But, when you look at the whole system, if you didn’t seal the connections, you could be at 10-20 percent leakage or inefficiency of the system — even with round duct. In order to meet energy codes and standards, people are either using gasketed fittings or contractors go back and literally have to seal it with a commercial-grade sealant.

“When it comes to HVAC contractors, they’re looking for the quickest, most cost-effective way to assemble ductwork in the system and seal it to reduce their total costs,” he continued. “We offer a product called Velocity™ gasketed duct, which is a self-sealing, gasketed joint system. When you put it together, it creates an airtight seal that meets leakage standards and codes so there is no need to use a secondary product to seal the connection. It’s probably the most effective method of doing so.”

Bryan Barnes, senior director, business development, Aeroseal LLC, agrees that green ductwork means sealing ducts to increase energy efficiency.

“Leaky ducts don’t just come from connections, they are often created when subsequent work is done to the home through seasonal changes, structural shifting, and a variety of other influences,” he said. “The good news is everybody is talking about the importance of sealing ductwork.

“Sealing ductwork has two major benefits: It saves efficiency from an energy standpoint, and it ensures the equipment you’re putting in the house operates at its intended specifications,” continued Barnes. “So, if you install a 20-SEER air conditioner but you don’t seal the ductwork, you’re going to have about a 25 percent degrade in the potential of that system. That’s why I would consider it green. Sealing ductwork means you’re using less energy and minimizing emissions, which is better from an environmental and comfort standpoint in the home.”

According to Barnes, consumers are becoming more educated and aware of the potential for energy savings in addition to comfort and IAQ in homes. “Ten years ago, people didn’t realize there was a comfort solution without tearing out walls and starting all over again. Duct sealing is a pretty simple solution to make you more comfortable and improve the health and safety of your home without having to destroy it. Additionally, duct sealing opens up potential market opportunities for contractors. Traditionally, HVAC contractors have been interested in box exchange and replacement. In most areas, about 8 percent of homes offer replacement sales. If you have 100,000 homes in a market, 8,000 of them will need replacement equipment during that year. The biggest benefit to duct sealing is every one of those homes are potential targets for HVAC contractors. It opens up the ability to increase lead generation, sales, and profits. It also sets them apart from the competition. As consumers become more educated and energy codes stricter, I believe contractors will have to look at these other avenues, like duct sealing, in order to be successful.”

Barnes noted that Aeroseal technology exceeds all existing code enforcements and is prepared to exceed all projected codes, as well. “We guarantee our product, measure it, and verify it through pre- and post-testing. From a consumer standpoint, it truly is a profit-generating technology that will continue to become more important as we move forward with all of the energy and code enforcement. By sealing 95 percent of duct leaks, Aeroseal turns existing ductwork into high-efficiency green ducts.”

According to Mark Smith, business development manager, GreenSeam Industries, a DMI company, reducing duct leakage, improving energy efficiency, and reducing material and waste are the primary components of sustainable duct systems or green ductwork.

“We saw the trend take off in the early 2000s, when energy costs started to rise significantly,” Smith said. “Payback on energy-improvement technologies or construction techniques started to make a lot more sense. That’s when we saw the shift to engineers, architects, and the HVAC industry really focus on sustainable construction and energy savings. As energy codes have increased, they’ve pushed companies to work more and more toward energy management and reducing duct system leakage.”

Additionally, energy-efficient duct systems and sustainable construction have become more mainstream in the industry, Smith noted. “There’s been a market shift at this point. People have become accustomed to asking for these types of products and construction techniques. They’re just starting to become a requirement instead of something used only on LEED projects.”

GreenSeam+ sealed pipe and fittings reduce duct system leakage without the use of costly and time-consuming mastics and tapes.

“GreenSeam+ eliminates both material and labor costs associated with external sealing and taping,” Smith said.

The idea of energy conservation or increased system energy efficiency is not anything new, noted Randall Hinden, CEO of Duro Dyne Corp.

“Green ductwork mostly has to do with the efficiency of a system,” he said. “It doesn’t only have to do with recycled materials — it also has to do with being more efficient energy-wise. It’s green because you’re saving energy.

In addition to that, another point in the ductwork system that’s been a problem and carefully looked at now is the natural leakage of a duct system,” continued Hinden. “We offer a number of different insulation adhesives that adhere the fiberglass liner to the sheet metal. But that, in itself, is not sufficient and doesn’t meet SMACNA [Sheet Metal and Air Conditioning Contractors’ National Association] regulations. So, we also sell welded insulation fasteners as well as our Insulflex insulated flexible duct connector.”

Insulflex features an R-value of 4.2 and is a thicker insulation. It is a nonporous product that eliminates air leakage, said Hinden.

“Ultimately, these products are going to be used more and more now because of the industry and how the standards are changing,” said Ulm. “It usually starts in the commercial market and then works its way down to the residential level, and it’s working its way down very quickly.”

Publication date: 9/19/2016 

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