Behind the façade and the accolades, a well-designed hvac system makes this facility comfortable for its users. Rock Hill Mechanical, a 44-year-old contracting firm based in St. Louis, designed and installed a system that matches the building’s upscale image and caters to its special needs.

House of Glass

The complex is actually composed of two buildings — one a four-story and the other a five-story — that are connected by an enclosed link. The large windows that surround each floor presented temperature-control challenges throughout the building, but they particularly affected the data center and the conference center.

The data center is the core of Unity Health’s billing operation, and its mainframe and network computers require a climate of 40% to 50% rh to prevent static electric shock, according to Mike Schriever, project manager for Rock Hill Mechanical.

Most data centers, he says, have few windows. This one, however, has 6-ft-tall sections of 1-in.-thick insulating glass around the entire floor.

“When you have insulating glass and a higher level of relative humidity, there’s a certain point when the temperature of the glass gets so cold that the humidity will condense on the glass,” says Schriever.

“We had to meet some tight tolerances to maintain the humidification levels for the computers, yet prevent condensation on the glass.”

His team installed four 20-ton, direct-expansion, Liebert environmental control units in the data center in lieu of water-cooled units. Each unit has multiple compressors so that if one goes down, the entire system isn’t lost, according to Schriever.

Designing a suitable system for the large conference center provided another challenge because of the large windows.

“The owner did not want any hot water perimeter radiation at the base of the conference room, so that left us with the challenge of how to cover the glass without using hot water radiation,” says Schriever.

“We did that with series-powered fan terminals and a special type of diffuser that splits the air two ways, horizontally and vertically, and washes the glass.”

They designed an airflow pattern that would provide adequate circulation without disturbing the center’s drop-down projection screens.

Vertical Distribution

Since certain portions of the complex are occupied 24 hrs a day, Rock Hill installed pairs of rooftop air-handling units (manufactured by The Trane Company) that are each connected to a single riser.

“We paired a 100-ton unit with a 75-ton unit so that if someone wants to come in on the weekend and they’re the only ones in the building, they can push an override button and only the smaller unit will turn on,” says Schriever.

“Only the floor that’s occupied will be cooled. The rest of the floors will stay in unoccupied mode.”

The single-riser format also complemented the building’s design.

“Usually we don’t put two units together into one shaft and feed down vertically. There was only one space for vertical duct distribution because of the way they [the architect and engineer] programmed the space,” says Schriever. “There wasn’t room for individual risers for each floor.”

Since most of the floor space is column-free, the structural steel beams are thicker than usual. “In certain areas, the beams are 36 inches deep, which, when combined with 9-foot ceilings in a 13-foot, 6-inch floor-to-floor space, left little room for ductwork and piping,” says Schriever.

“We had to coordinate our work with the structural engineer and create openings in the beams so we could run our horizontal ductwork and piping.”

Making it Happen

Ultimately, true teamwork and the design-build process enabled the Rock Hill team to install their system efficiently within a tight schedule, according to Schriever and Steve Comeau, vice president of business development for Rock Hill.

Comeau likes to compare the cooperative interaction established on the job to that of a symphony.

“McCarthy [the general contractor and construction manager] was the conductor, but every piece of the symphony — every piece of that team — had equal input to get the entire project accomplished.”