PITTSBURGH — Developers of the $328 million David L. Lawrence Convention Center in Pittsburgh, which is now under construction, are calling it a “first-of-a-kind” facility, featuring environmentally sustainable systems such as natural daylight and natural ventilation. These “green” features are intended to make the convention center a “healthier” building for both visitors and employees.

Complicating the goal of natural ventilation, however, is the fact that there is a large flow of trucks into and out of the center for each convention. That type of heavy vehicular activity can put a heavy strain on the heartiest of ventilation systems.

To meet the challenge, Limbach Inc., the hvac contractor performing the work and one of the largest contractors in the country in terms of hvac, plumbing, piping and sheet metal work, is installing more than 2.5 million pounds of ductwork— including more than 900 feet of a massive 20-ft. wide exhaust plenum located above the convention center’s second floor loading dock.

According to Mike Gunning, Limbach’s superintendent and project manager for the project, the plenum will have multiple exhaust fans and sound attenuators to collect both exhaust and noise from both the first- and second-floor loading docks, relieving much of the load from the building’s main ventilation system.

Installing the massive 236”X26” ductwork is easier than it would seem, said project foreman Dan Shane. “Five-foot sections are prefabricated for us by Williard Inc. using J-Flange Four-Bolt Connectors from Ward Industries, and those sections are shipped directly to the job site.”

Because of the four-bolt connection, the huge sections of ductwork can be lifted into place with a forklift, attached to the half-inch threaded rod sections that have been dropped through the floor above, and bolted into place. An intermediate rod, which supports the weight in the center and stiffens the entire structure, is fastened to the center of each piece. “It’s gone up real well,” Shane said.

Huge sections of duct were lifted into place with a fortlift, attached to 1/2-in. threaded rod.

40 feet of duct per day

Using this method, more than 40 feet of the huge system can be installed per day, said Shane. Ward Industries, Monessen, Pa., is providing all of the flange connections for ductwork larger than 42 inches in the facility.

Ward’s J-Flange is roll-formed from 20-gauge steel, which is doubled over and reinforced through a unique system of ridges for added strength. It is available in 20-ft. lengths, ideal for oversized installation. Ward’s corners, the heart of the connection, are stamped from 11-gauge galvanized steel, giving the entire structure a high degree of sturdiness. The Ward J-Flange connection complies with all of SMACNA’s duct construction standards.

“Once the duct is up there, there’s not much work fastening it together,” Gunning said. “We just need to fasten the four bolts and install the 6-in. metal cleats, which just snap on at 12-in. on center. It’s much quicker than a Van Stone flange connection, which would require angle-iron flanges welded to the duct, and having bolts on every six or eight inch centers around the whole flange. It’s a very clean installation.”

Rafael Vinoly Architects PC was chosen as the primary architect for the design of the new David L. Lawrence Convention Center. The design, chosen by a panel of jurors with experience in hospitality, planning, architecture and economic development, was approved by the Southwestern Pennsylvania Convention Center Design Commission. An art commission will also assist in further development of the Convention Center.

The design is striking for its cantilevered roof, which was inspired by the three suspension style bridges, called the Three Sisters, that connect downtown to the North Shore. The roof also serves as a “convecting surface” that will permit natural ventilation as well as act as a cooling system when water is sprinkled on it in hot weather.

When completed, the convention center will contain 330,000-sq.-ft. of exhibition space and include a main hall, a secondary hall, and a ballroom. Vinoly’s design includes 242,000 sq.-ft. of exhibition space, a 96,000-sq.-ft. secondary hall and 35,000 sq.-ft. ball room. Phase one of the construction, totaling 126,000-sq.-ft. of exhibition space and nine meeting rooms, is scheduled to be completed on January 1. Phase II is set to open in October. The grand opening will be in March 2003 with the completion of Phase III.

The 900-ft. plenum will eventually run the entire length of the building. “We’ll be working on that for the next two years,” Gunning said.

Most exiting ventilation systems require inside air to be continuously filtered and ventilated throughout a closed system. The “green” ventilation system featured at the Lawrence Convention Center contains a system of dampers and air handling units that enable fresh outside air to be brought into the system and vented into the exhibition hall.