A Capital Job on Engineered Building Systems

Residents of Utah's Wasatch Front, where the State Capitol Building proudly stands, have been warned that it's not if, but when, a major earthquake will strike. Taking heed, the state undertook a structural analysis of the building during the 1990s, and the findings didn't look so good: a moderate earthquake could cause potentially catastrophic damage and deaths.


Residents of Utah's Wasatch Front, where the State Capitol Building proudly stands, have been warned that it's not if, but when, a major earthquake will strike. Taking heed, the state undertook a structural analysis of the building during the 1990s, and the findings didn't look so good: a moderate earthquake could cause potentially catastrophic damage and deaths.

As a result, a building team was assembled to complete a seismic retrofit and historic restoration of the more than 90-year-old building.

At the end of the day, in order to mitigate the impact of earthquakes, the Capitol underwent seismic base isolation and now rests atop 265 base isolators—layers of rubber and steel plates surrounding lead cores that absorb energy. The isolators allow the building to move as a whole mass during an earthquake, rather than remaining rigid only to be shaken violently apart.

Concurrent with seismic work, the Capitol was updated completely with state-of-the-art systems including electrical, air conditioning, heating, lighting, voice/data communications, security, and audio/video systems. The historic finishes of marble, gold leaf, and stone were also restored and modern systems were concealed to maintain its classic architecture.

MEP's critical role

The Utah State Capitol Building is now a modern, up-to-date facility, but the process in getting there wasn't so simple. Essentially, MEP engineers faced three main challenges:

Pathways/distribution: The building, constructed in 1916, was not designed to support infrastructure for modern mechanical, electrical, and IT technology systems.

Correction of historic spaces and concealment of modern systems: Identifying space for and implementing modern systems and devices without interfering with historic architecture were MEP challenges, as was removing previous renovations that conflict with the original design.

Designing advanced technologies: Designing voice/data, audio/video, and other electronic systems to make this iconic building one of the most technically advanced state houses in the nation.

Even though interstitial spaces, concealed by false ceilings, are usually designed into buildings to house HVAC ducts, electrical, fire protection, plumbing, and communications distribution systems, that option was out of the question for the Capitol Building because drop ceilings from past renovations had been removed to bring the facility back to its original architectural splendor. Adding false ceilings would have interfered with historic windows that stretch to the plaster ceilings, and also would interfere with historic molding, artwork, fixtures and other details. Consequently, another solution had to be reached.

Instead, electrical and mechanical equipment, including variable air volume boxes, were installed in the attic and the basement, while the four floors between attic and basement—the most public and historically significant areas—remained essentially unaffected.

But the next question was how to distribute these new systems throughout the building without interfering with the architecture.

“We had to figure out how to do this so visitors to this public house and jewel of the state would think, 'They really haven't done a thing to this building except clean it,'” said Todd Rindlisbaker, PE, CPD, QCxP, LEED AP, mechanical engineer with Spectrum Engineers, Salt Lake City.

Fortunately, as the engineering team conducted extensive reviews of existing conditions and old plans of the Senate, Supreme Court, and Governor's meeting spaces, the team discovered long-abandoned air shafts that were perfect for running modern ducting and other distribution systems.

From a mechanical perspective, the thick walls allowed for approximately 8-in.-wide ducts. Sidewall diffusers were used to distribute conditioned air into the rooms, and in this way, “floor space lost to thickened walls was minimal,” Rindlisbaker said, “and the imperative to save original ceilings was achieved.”

But while electrical and technology systems were set up to share these thickened walls with ducting and plumbing, that only solved part of the electrical/technology distribution problem.

“We had to run more conduit and cabling to more places than HVAC ducts need to go and we couldn't call for every wall to be thickened,” said Spectrum's Dave Wesemann, PE, LEED AP, electrical engineer.

Once the electrical and technology systems were placed on the correct floor using vertical chases in thickened walls and by stacking communications closets, horizontal distribution of electrical and communications could be achieved by channeling through existing concrete floors and coring through structural clay tile ceiling material. The clay tile was interrupted every 2 ft. or less on center by concrete beams, which also were cored to make room for conduit. Many times, the team couldn't penetrate the ceiling without causing structural issues, so paths had to be carefully coordinated.

Because the Capitol will probably not be renovated again for another 100 years or more, if ever, the project was considered a once-in-a-lifetime opportunity. Consequently, systems were designed in anticipation of future technologies, expansions, and upgrades. For example, Wesemann said, “We oversized homerun conduits so they can always pull new or re-pull larger wire.”

Gerald F. Nelson, BSAT, principal technology designer for the Capitol restoration and principal with Spectrum Engineers concurs: “This renovation was our only chance to get into ceilings and walls to run conduit.”

Consequently, extremely careful planning was required to design technology raceways appropriately. Nelson's team organized raceway systems and precisely drew them for the contractor. Spare capacity was also designed in and fiber backbones were carefully planned.

“A lot of time went into making sure that in the future they will not have to rip out walls or floors or ceilings,” said Kurt Dallinga, PE, RCDD, CTS, technology engineer on the Capitol project and an associate with Spectrum Engineers.

Ingeniously hidden

To meet Utah fire code, the fire protection engineers were required to locate smoke detectors throughout common areas and corridors, which are the most aesthetically sensitive spaces in the building.

“Seeing the smoke detectors on the plan, the architect told us to come up with a way to meet the fire code and not have those detectors visible. This really caused us to think outside the box,” Wesemann said.

On another recent project, Spectrum had implemented early warning air sampling to detect smoke with small, inconspicuous tubes. It was just the solution that the Capitol needed. A VESDA system was implemented with minute sampling tubes ingeniously hidden in molding. Even historic-looking light fixtures were used to double as smoke detectors.

“The air sampling system is orders of magnitude more sensitive than traditional fire detection. We were able to achieve our aesthetic, code, and safety goals while better protecting this living museum,” Wesemann said.

When it came to designing the building's technology system, Nelson toured the U.S. Capitol and studied other renovated state houses and historic structures in search of industry best practices. However, he said that Utah's Capitol has far more advanced systems than any of the projects he's studied. “From a technology standpoint, the systems at the [Utah] Capitol are second-to-none,” said Nelson. “We designed all of the associated routing and distribution and planned carefully to make it a very simple handshake to take what is captured, produced ,and edited at the Capitol and hand it to the broadcasters so they can broadcast it.”

Nelson compares the central control room in the basement to transportation hubs where all modes of transportation go to and are routed from. The same is true of all audio and video signals at the Capitol. High Definition Serial Digital Interface and digital audio originated anywhere in the building are sent to the central control room. “By using central routing architecture, the Capitol is ready to meet needs that haven't even been thought of yet,” he said.

A fiber optic backbone routes to all the data systems and to all the audio/video locations and systems. It uses CobraNet, a digital audio format allowing multiple packets and streams of audio to be sent throughout the building.

How far into the future is the building's technology designed to anticipate? A new phenomenon occurring in the audio industry helps answer the question. When GSM-type mobile phones transmit near a microphone, it causes a very unpleasant noise on the sound system.

The phenomenon would have occurred at the Capitol if the engineering team hadn't taken special measures to eliminate it. “We specified technology on this project that did not exist yet, requiring bidders to call microphone manufacturers for information, because it was unpublished at the time, on products that address this problem,” said Nelson.

As early as 2003, Spectrum's designs for video distribution, production, routing, and editing systems met FCC standards for broadcasters that wouldn't be mandated until 2009. Pointing out that TV resolution has stayed the same for more than 50 years, since the time it was first broadcast until the advent of HD, Nelson said, “Every broadcaster I've talked to says that they are going to be at HD for a long, long time.”

Two basement production rooms allow staff to produce HD CSPAN. Non-HD TV is such low definition that high-resolution computer images cannot be used for TV broadcasts. “Because we have HD throughout the Capitol, we're able to interchange between computer-generated and broadcast images. Computer images can be converted to broadcast images and manipulated in production rooms,” Dallinga said.

Incidentally, the engineers also designed similar advanced technology systems for the state's Senate and Supreme Court buildings, in addition to a video conferencing room for the Capitol basement.

Search for space

Yet another challenging issue, as with most retrofit projects, was finding space. With only 330 sq. ft. inside the Capitol designated for mechanical systems, an additional location was needed. Consequently, heat exchangers, pumps, and six air handlers are sited on the new podium that wraps around the exterior of the Capitol and is located primarily below grade.

The podium acts as a terrace around the building that visually enhances. In fact, Rindlisbaker said that it also serves another critical purpose: creating a 45-ft. to 60-ft. barrier to potential terrorist activities. Essentially, vehicles can't get any closer to the building than about 50 ft.

Also, a 3-ft.-wide moat separates the podium from the Capitol, allowing the building to move independently from the podium. Because the podium is not base-isolated, it would move with the ground during an earthquake, while the Capitol, which is base-isolated, should remain relatively stationary during such a natural catastrophe.

Piping for gas, fire sprinkler, domestic water, heating, cooling and sewer enter the Capitol by passing through the moat. Because the buildings allow for 2 ft. of movement away from each other during an earthquake, the pipes also must be able to move 2 ft. in any direction without breaking. This is achieved through the use of flexible pipe loops, which form a U-shape that hangs down into the moat, allowing the required movement.

Historic preservation

While the engineers were dealing with technical and space challenges, the historic integrity of Utah's Capitol Building also had to be preserved. For example, Rindlisbaker said, “We required the manufacturer to provide historic-looking covers for the direct digital control temperature sensors and CO2 sensors for safety and fire detection.” And for the fire sprinklers, the team worked out ways to locate everything in the basement and attic, and then run laterals through the walls and use sidewall heads, which are concealed as much as code allows by cove molding.

With an eye for efficiency, lighting controls and space occupancy sensors were integrated into the HVAC control system to turn on and off lights and control ventilation rates.

“Early in the design process,” Rindlisbaker said, “we sat around a table with all involved parties—mechanical, electrical, and controls and commissioning. We discussed what systems were to be used and considered grill openings and location of equipment and how it was to be controlled.”

One example of this type of collaborative design work is the custom-designed smoke control panel. “All of the components are in place and have already been worked through,” Rindlisbaker said. “The difference with the fire control panel at the Capitol is that we created the panel in the design by identifying every device and drawing out the control panel. Nothing was left for the contractor to guess or interpret.”

True collaboration

Overall, the Capitol project was truly collaborative as the many disciplines, architect, owner, contractors, and artisans pulled together to update a monument to the citizens of Utah and bring it back to its original architectural splendor, making it viable to house the state's leaders for another century.

Project at a Glance

Utah State Capitol, Salt Lake City

Size : 320,000 sq. ft.

Cost : $212 million

Architect : The Capitol Restoration Group—a joint venture of VCBO Architecture and Max J. Smith Architecture, Salt Lake City; Schooley Caldwell Assocs., Columbus, Ohio; and the Utah Capitol Preservation Board led by architect David H. Hart, AIA

MEP Engineer : Spectrum Engineers, Salt Lake City

Contractor : Jacobsen/Hunt Joint Venture, Salt Lake City

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