BOSTON - When international architectural-engineering (a-e) firm Cannon Design (CD), specified fabric duct for its own branch offices, some manufacturers looked at it as a milestone for the fabric duct industry.

CD is a top-25 a-e firm based in Grand Island, N.Y. The company said it had several motives for specifying fabric duct when moving its offices to the 20,000-square-foot, 14th floor of the 41-year-old Saltonstall Building that’s now managed by CB Richard Ellis/New England.

CD architects wanted to retain the spacious feel of the open ceiling and semi-industrial appearance that the building’s owners had left exposed during the building’s renovation. CD’s in-house project managers liked the fact that fabric duct would complement, and also add a soft contrasting appearance, to this industrial style.

After a hands-on presentation from manufacturer’s representative Buckley & Associates, Hanover, Mass., CD architects chose fabric duct.

LINES AND SPACE

Function followed form when CD’s project engineer, Dave DeMoura, agreed to use fabric duct for its performance and value-engineering benefits. Besides even air distribution from the linear vents, fabric duct also provided an estimated installation labor savings of 30 percent versus metal duct. “I like the uniformity of air distribution the linear diffusion gives us,” DeMoura said.

CD’s space layout has design studios and offices on opposite ends of the floor, with a reception area, conference suite, and support functions between them. Each studio/office cluster has six 12-inch-diameter by 30-foot-long runs of DuctSox fabric duct. Four runs supply the open landscape office area, and two others supply perimeter offices.

A Trane 20,000-cfm air handler provides cooling via the air distribution system. In addition, 21 Nailor Industries fan-powered, variable air volume (VAV) boxes feed the fabric duct and other air distribution channels.

DeMoura specified commercial Verona fabric for the ductwork. The fabric’s porosity allows 15 percent of the air to flow through the fabric and the remainder to flow through linear vents. “The fabric porosity and linear vents of the fabric duct, combined with the temperature precision of the fan-powered VAV boxes and return air plenum, provide superior air comfort levels for employees,” he said.

MECHANICAL NOISE

Open architectural ceilings with VAV boxes tend to radiate more noise in an office space. However, the fabric duct helps minimize equipment noise transmission, said DeMoura.

Other areas without fabric ductwork, such as the suspended ceiling with recessed metal duct and metal linear diffusers in the conference suite, have their own noise solution. By insulating the metal return ductwork and shaping the return air path in a “Z,” mechanical equipment noise is significantly attenuated.

EMCOR Services - Commonwealth Air Conditioning and Heating Inc. Division, installed the sheet metal and fabric duct for the project.

While Cannon was responsible for the HVAC on its own floor, building owner Mass Development/Saltonstall Building Redevelopment Corp., and mechanical contractor J.C. Higgins Corp., provided two 800-ton Trane chillers; three 1,600-gpm Baltimore Aircoil cooling towers; two 1,250-MBtuh Lochinvar boilers; and two RBI Boilers plate-and-frame heat exchangers as part of the building’s entire renovation. Harrington Bros. Corp. provided sheet metal fabrication and installation for the general building HVAC.

“Given the fact that our company had a limited budget for the buildout of this floor, fabric duct and the open ceiling architecture still look great and function well,” said DeMoura.

Publication date: 04/02/2007