The Many Advantages of Fabric Duct
Delivering a wide range of installation and operating benefits, fabric duct has slowly been finding its way into a number of projects involving open spaces, such as food processing plants, supermarkets, indoor swimming pool facilities, gymnasiums and convention centers. As an alternative to traditional metal ductwork—which often requires dozens of grills and diffusers for air distribution...
Delivering a wide range of installation and operating benefits, fabric duct has slowly been finding its way into a number of projects involving open spaces, such as food processing plants, supermarkets, indoor swimming pool facilities, gymnasiums and convention centers.
As an alternative to traditional metal ductwork—which often requires dozens of grills and diffusers for air distribution—the polyester cloth-fabric duct has customized perforations along its length that enable it to provide draft-free air distribution at a low velocity.
And the installation is a lot less labor-intensive.
"Because fabric duct comes with its own hangars, it's easier to install, and saves a bunch on labor costs," explains Nate Valukas, a mechanical designer with Engineering Services Group, Knoxville, Tenn., who recently specified fabric duct for a fitness complex in their home town.
Another benefit is the elimination of condensation problems.
During the design of the 250,000-sq.-ft. column-less exhibit hall at the new Pittsburgh convention center, engineers at Burt Hill Kosar Rittelmann, Butler, Pa., wanted to utilize unconventionally cold 41°F air to be able to cool the space with a smaller volume of air. However, without insulation, this would have made the metal duct prone to condensation.
According to Dave Linamen, P.E., a principal with the firm, his engineers were able to work with the fabric duct manufacturer and "design a porosity into the fabric to create a small microclimate around the ductwork to completely eliminate condensation."
Also, for the convention center, rigid metal duct would have had severe limitations due to the fact that the cable structure supporting the column-less roof was designed for motion, sometimes as much as 2 feet. In addition, the designers wanted to run the duct along the curvature of the cable for better aesthetics.
"At first the fabric duct seemed too good to be true and we were very skeptical, but it really was a solution that solved all of our concerns," says Linamen.
Not only that, but Linamen estimates that the fabric duct saved the Pittsburgh Sports and Exposition Authority close to $1 million in installation and operational costs.
In some cases, additional savings can be gleaned because the ceiling requires less support due to the duct's light weight. For Ed Briner, P.E., a senior mechanical engineer with Gannett Fleming Inc. in Camp Hill, Pa., an additional benefit came to fruition through the specification of fabric duct at a printing plant.
"Because we chose a white polyester [fabric duct], we found that the duct has reflective properties and has helped with the lighting in the building," notes Briner.
In addition to white polyester, manufacturers offer several choices of fabric materials and air distribution patterns.
Not an end all, be all
Although fabric duct appears to be an impressive alternative to metal, it's not ideal for all applications.
"For areas with small zones—like an office building—or tight control zones—like a laboratory—fabric duct would not be a solution," notes Linamen.
Also, even though the product is well-used in Europe, it is still a fairly new concept in the U.S. and requires a learning curve.
For example, the first time Valukas specified the product, he had to work with the manufacturer throughout the design process.
"I don't know that the typical engineering firm wants to take that time," comments Valukas.
However, as the product's benefits become better known, more engineers will be brought on board.
In addition to easy installation, condensation prevention and draft-free air distribution, manufacturers also claim that the fabric can be taken down, piece by piece, and washed in a commercial laundering machine.
But as Briner says, "The main advantage is really cost savings."
Benefits of fabric duct
Operating cost savings
Draft-free air distribution
Installation ease and cost savings