Hanging heavy ductwork from a 40-foot-high ceiling with no access for machine lifts was a risk Kawa wasn't willing to take with his budding company, Mechanical Engineering & Construction Inc., one of Baltimore's fastest growing HVAC design-build firms. Kawa's company has blossomed to 75 employees in less than two years after Kawa co-founded it with partner Rich Beattie.
The fact that fabric duct is 90 percent lighter than its metal counterpart was definitely a safety factor for Kawa when considering 80-foot runs of 48-inch diameter duct had to be hung in an area with poor footing from an excavated slab, or second-story flooring unable to support heavy equipment, or poor access.
John A. Coakley Jr., a salesperson at manufacturer's rep firm Ward-Boland Assoc. Inc. (Owings Mills, Md.), helped present and demonstrate the fabric duct to the selection committee, which included project architect Tim Kearney, Architecture Alliance (Annapolis, Md.); Rams Head Live owner Bill Muehlhauser; Joe Brown, president, and Ryan Clark, project manager, of general contractor Brown Contracting Co. Inc. (Annapolis). All parties liked the smooth aesthetic look of fabric duct and the streamlined linear vent that runs the entire length of the duct.
Less Time To Install
The selection committee felt the black TufTex™ fabric duct manufactured by DuctSox (Dubuque, Iowa) complemented the 24,000-square-foot brick-and-timber building's industrial décor. Rams Head Live is a $5 million venue, which has already attracted top touring music stars such as B.B. King, Phil Vassar, and Elvis Costello; the building conforms to the industrial style of the Power Plant Live district.The site is a former utility plant that has anchored a rejuvenated downtown Baltimore area with a dozen nightclub, music, and other entertainment venues developed by Baltimore-based Cordish Co.
Beside safety benefits, installation time was cut from an estimated three weeks for metal duct to one week for fabric duct.
"It wasn't a fast-track project, but anytime you reduce installation time by two-thirds, you're going to save money and speed the project along," said Kawa, who has used fabric duct previously in warehouses and seen it used in indoor pool enclosures.
Kawa did use metal duct as a plenum out of the 42,000-cfm rooftop heating-cooling unit by Aaon Inc. (Tulsa, Okla.), and track through the roof to the DuctSox runs. Maintaining the 74 degree F set point temperature is handled with a Honeywell (Minneapolis) single programmable thermostat and sensors in the return air. Three 2,000-cfm rooftop exhaust fans by Greenheck (Schofield, Wis.) handle the cigarette smoke and other indoor air quality (IAQ) concerns.
Ventilation design for a nightclub is particularly critical in terms of smoke, airflow noise, air distribution, and adhering to American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) standards, but without sacrificing energy efficiency, according to Stephen Wagner, Mechanical Engineering's director of engineering.
While the architect ingeniously removed a large portion of second story flooring above the stage to create great sightlines from the balcony, the void created an airflow challenge. Wagner specified a complicated 18-inch-diameter DuctSox fabric duct to conform to the various angles and offsets of the balcony edge.
The system included linear venting at the 6 and 4 o'clock positions to direct airflow downward on the patrons who need it most. The black ductwork is hung from the façade of the balcony with hidden angle brackets that support an H-track suspension system.
"It really blends in to the décor and I think patrons perceive it as decoration rather than functional ductwork," said Wagner.
Quiet, Please
Wagner also likes the long but gentle throw of the balcony ductwork. Strong, drafty airflows would have created a series of swinging pendants with suspended acoustical tiles, lighting, and sound systems surrounding the stage."What I really noticed was how quiet fabric duct is in a concert situation," said Wagner. "Already we're fine-tuning some of the metal ductwork throughout the space with sound absorption because it transmits too much mechanical equipment noise."
Baumgartner Inc. (Baltimore) handled the airflow system balancing. While metal ducts and diffusers were adjusted on-site for proper airflow, the fabric duct was custom manufactured to Wagner's specifications for proper airflow.
While fabric duct is the main air distribution system in the 15,000-square-foot concert space, ductless mini-split DX units by Mitsubishi (Suwanee, Ga.) provide the majority of cooling and heating in the venue's small bars, meeting areas, large restaurant, catering kitchen, and behind-the-scenes support areas.
Publication date: 08/29/2005
