New lease on life

Taking a ’60s-era building to its core, work is underway to create the Constitution Center, which promises to be the largest Gold-certified LEED building in the United States.

by Clair D. Urbain

The U.S. Department of Transportation building is undergoing a tremendous transformation. The building has been stripped of its former, albeit aged, beauty and function as it undergoes a metropolitan metamorphosis. It’s being replaced by a building design that better reflects the new millennium need for greater security, information and energy efficiency. Even the building is being renamed Constitution Center, signifying its new lease on life.

Plus, it’s very likely going to achieve Gold level Leadership in Energy and Environmental Design (LEED) certification. That’s the goal of building owner David Nassif Associates, reports Tim Jaroch, managing general partner.

“Since this building will likely have government tenants, what we can charge for rent is largely proscribed. But having the Gold level LEED (NC) certification gives us a competitive advantage vs. other buildings. It can only help us market the building,” he says.

There are two types of LEED certifications: Commercial Interiors (CI) and New Construction (NC), which covers the base building and renovations. At the Constitution Center, it will be up to the tenant to achieve LEED CI certification. “It is entirely in their hands as to what level they would like to achieve,” says Jaroch.

The ambitious LEED Gold (NC) rating is possible with the combination of great location and close attention to detail. Several LEED points are gained because the building has a Metro station built into it; other points are achieved because it is a renovation rather than new construction.

The former Department of Transportation building in Washington, D.C. is undergoing a metropolitan metamorphosis to become the Constitution Center, a Level IV blast-resistant building that uses chilled beam technology to heat and cool the building. Widely used in Europe, this is the first large-scale installation in the United States and promises to be more effective and efficient than conventional HVAC systems.

The demolition process required careful management and tracking to assure the bulk of the material was being recycled, says Jamie Pacala, James G. Davis (Davis) Construction assistant project manager who is coordinating LEED efforts.

“We are above 76 percent recycling at this point on the site. Unfortunately, any finished painted wall couldn’t be recycled, but all of the carpet was able to be recycled. All metal that could be recycled was separated on the site,” he says.

The carrera marble exterior is being recycled into a sand/marble mix that’s sought after by area golf courses for paths and sand traps.

“In the LEED process, we can track recycling by the cost of the materials or by its weight. We did it by the weight of the material. It is difficult, and much of it is up to the demolition contractor. To this point, we have produced 24,000 tons of debris and have recycled 18,380 tons. LEED awards one point for 50 percent recycling and two points for 75 percent or more recycling of construction waste,” Pacala says.

Let the demolition begin
In total, the project covers more than 2.1 million sq. ft. Demolition of the 40-year-old façade and interior began in July 2007.

Davis team members, left to right, front row: Brad Cordek, Jamie Pacala. Back row: Tony Lee, Ted Holt, Bill Bundens.

Inside and out, the building was gutted to its basic frame to install an energy-efficient infrastructure and to rebuild the structure to meet strict Level IV blast resistance standards, says Ted Holt, Davis Construction project executive.

“We have stripped it to its shell, keeping its core elevators. The old building was an Edward Durrell Stone design, who also designed the Kennedy Center, and was built in the late ’60s. Its exterior was made up of 2'-wide panels of white carrera marble separated by narrow windows, which allowed little natural light inside the building. It also blocked many of the great views of the Capitol area. While marble was an economical building material at the time, it didn’t age well,” says Holt.

Hysteresis is the culprit in the marble panels’ deterioration over time. “The panels develop minute cracks due to heating and cooling cycles from the sun’s rays and the heating and air conditioning inside the building. Moisture then works its way into the cracks, causing the marble panels to bow and eventually pop out of their mounts or crumble. Once this process begins, it’s irreversible. The building required a full-time mason to maintain the exterior and, after 30 or 40 years, the exterior marble was buckling and in danger of falling off,” says Tony Lee, senior superintendent for Davis Construction.

Surprisingly, the marble façade was easy to remove. Working from swing stage scaffolds, workers used 3-lb. sledges to crack the marble which fell to a bed of sand below.

The block-square building has a 90,000 sq. ft. courtyard and had 24 miles of interior walls that had to be stripped to the core, says Holt. “The building has 21 elevators that have to be modified, and four new elevators are being added to service the office floors. We will also add six shuttle elevators that will take building occupants from the three-level basement garage to the lobby level. It’s part of the advanced building security features that developed since the Oklahoma City and 9/11 incidents,” says Holt.

As crews removed the exterior and interior of the building, the demolition subcontractors had to work in concert to remove debris.

The typical floor structural load capacity was such that skid-steer loaders couldn’t cross paths within the same floors and, as material dropped down trash chutes, they couldn’t work over top of each other. “We had full-time monitors direct traffic between floors. Nothing went out of the building or down the trash chutes without a Davis team member directing the work,” says Brad Cordek, Davis assistant project manager.

“We used the courtyard to gather and sort the debris. We dropped the debris from opposite corners of the building into the courtyard, and approached the work at 90 degrees from floor to floor for safety. It also spread the load of the working equipment so it would not overload the structure,” says Lee.

Once pushed into the courtyard, debris was sorted and hauled to 53' trailers on E Street. “The demolition subcontractors used wheel loaders to move the debris, and carefully selected them so their weight would not exceed the weight-bearing capacity of the courtyard and garage below,” says Lee.

The parking garage under the 5 1/2-acre facility is three levels deep and provides 15 acres in total space. “We added shoring in three levels of the garage to support the sorting in the courtyard,” says Cordek.

Although demolition is almost complete, structural limits continue to affect the project. Because of the tight perimeter of the site, the tower cranes must sit on the existing substructure. A large, steel-framed base was constructed to transfer the crane loads to the concrete building structure below. “With Holbert-Apple, a local structural engineering firm, we designed a tower crane base similar to what we’ve done on other renovations,” says Holt.

Reflecting the Davis commitment to safety, lock-out/tag-out protocol during demolition takes top priority on the site. Contractors follow a simple visual checklist to determine if power, water, cooling/heating lines and other infrastructures could be demolished.

“For temporary power and light, we had the electrician run temporary risers in each quadrant of the building in the old electrical rooms. For lighting, we used Wobble Light temporary work lights until the ceiling was removed. Since this is a renovation project, key water, sewer, elevators, and power had to remain live,” says Bill Bundens, Davis MEP project manager. “We used a standard marking on all utilities. If it was marked red, it meant, ‘Do not touch!’ If it was marked green, it could be removed. Everything was tagged and if anyone came across something that was not marked, it was assumed it was live and could not be touched until it was checked out and marked,” says Lee.

“We went with hi-vis safety vests on the site so Bobcat loader and other equipment operators can see all workers more easily. Even though demolition is nearly complete, we continue to wear the high-visibility vests,” says Bundens.

The previous HVAC system used ethylene glycol, which also had to be removed efficiently and safely. “During demolition, we had meetings with all of the contractors every Monday, Wednesday and Friday to coordinate all of the activity,” says Lee.

Blast resistance
To meet the needs of a greater pool of potential tenants, a Level IV blast rating design was incorporated into the new building façade. The all-glass curtain wall provides energy efficiency and panoramic views of the Capitol and surrounding area.

The new building exterior is energy-efficient glass that offers blast resistance and opens up panoramic views of the Capitol and surrounding area.

The curtain wall was developed as a design-assist project. “We all worked with Enclose Corp. (subcontractor), SmithGroup (architect), Weidlinger Associates (blast consultant), SK&A (structural engineer), and Wiss, Janney, Elstner Associates (enclosure consultant) to develop a custom anchoring system that can be installed efficiently and works with the existing structure,” says Holt.

Curtain wall window panels hang from these mounts. The original concrete mounts had to be removed and replaced to meet Blast IV standards.

Previously, the marble panels were held in place by concrete lugs spaced every 5' on center. The old lugs had to be removed, then more than 30,000 anchor bolts were epoxied into the façade of the building. To meet blast requirements, new street-side anchors are nearly twice the size of other anchors, and the courtyard anchors are designed to withstand blast forces. Once anchors are installed, aluminum anchors mount to these and then the glass panel clips onto them.

“Each glass panel unit is 5' wide and two stories high. Once the preparation work is in place, the glass goes up very fast,” says Holt. “This is repetitive work by nature, so once workers get past the quarter- or half-way point, production really increases because workers know what to expect.”

In the rest of the building, a variety of changes beef up its ability to absorb a blast. “All occupied areas of the building are protected, and the key garage structural elements and mechanical, electrical and plumbing system rooms have been hardened,” says Holt.

Heating and cooling system
Although widely used in Europe, chilled beam HVAC systems are a relatively new technology in the United States. The systems being installed in the building will lower heating and cooling costs significantly, and along with other factors, will result in a payback period of less than four years, says Jaroch.

SmithGroup, the architect/engineer on the project, suggested using this technology. More than 10,000 chilled beam systems are in use in Europe. Several manufacturers were considered, and TROX was selected.

Chilled beam HVAC systems use induction to transfer heat or cooling from water pumped through the system instead of a heat exchanger in a chamber in a forced air system. To fully test the chilled beam concept in Washington’s highly variable weather, the owner installed three different chilled beam systems in a controlled mock-up area in the penthouse before demolition began and collected data for more than a year. This data was instrumental toward the decision to select TROX. “The units use induction and about 10 percent of the air flow of conventional systems. It conditions air already in the building at a fraction of the cost,” says Bundens.

“This is the largest chilled beam installation in the United States. It uses units that are only 5" deep, a big plus where the space between the floor to the underside of the next floor is only 9'4". Most TROX units are 12" deep, and that’s the entire depth of our dropped ceiling plenum. We worked closely with the manufacturer, to develop a 5"-deep system that fits within our dropped ceiling plenum along with all of the other utilities. Its central plant is located within the penthouse and eliminates the need for separate HVAC systems on every floor in each quadrant. That opens up significant rentable space on every floor,” Bundens says.

Big Chill Chilled beam runs were specially engineered to be no more than 5" thick, maximizing dropped ceiling space.

The system moves a fraction of the air needed for other systems because water delivers heat faster than air, dispersing heat with water at a 10:1 ratio. “A conventional system moves 100 cfm; this system moves no more than 10 cfm, depending on demand. There are no moving parts in the units placed in the tenant spaces. There will be 6,600 of these units in the building, and they can be zoned with three to five of them together on this job,” Bundens says. He adds it is much more energy efficient than other systems. “As electricity goes up in price, it is much more efficient to use water to displace heat and introduce cooling through water than it is with air.”

Dan Donaghy, project manager for Pierce Associates, the mechanical contractor on the project, says this is the first chilled beam system Pierce has installed. “Installing the new system is not that much different from installing a conventional system except that it offers better unit accessibility once installed. The coil is inset into the finished and exposed sheet metal box and it can be accessed without removing the ceiling. There is also a cost savings because of the smaller ducting that’s needed and lower airflow means smaller units that take less power to operate. It’s an efficient system because it doesn’t blow new air in, it just combines and tempers air presently in the room,” Donaghy says.

The previous 50,000 sq. ft. penthouse had to double in size to accommodate the building’s newly installed systems, which include chillers, heat exchangers, cooling towers, boilers, electrical switchgear, emergency gen sets and other building support equipment.

“We had to spread the weight of the equipment across the building’s structure,” says Holt. SmithGroup used Building Information Modeling (BIM) in preparing the construction contract documents, but cost and time restraints limited the team’s ability to use it in the shop drawing process. It’s a useful tool if the right amount of time is put into it on the front end.

“It was helpful to a point, but it must be done at the shop drawing level for greatest effect. Contract drawings will pick up the big conflicts, but using BIM on the shop drawings allows the team to catch the nuances that are difficult to see in two dimensions, such as the locations of valves and gauges for long-term servicing of the equipment. It also needs to be across all disciplines. If the mechanical and plumbing contractor use BIM but the sprinkler contractor doesn’t, you lose some tremendous efficiencies,” says Bundens.

The team has worked together to prefabricate the risers for each quadrant. “The piping risers are delivered to the site complete in 40' sections. We settled on that length because that’s the maximum height the crane can lift, the sections fit on a standard flatbed truck, and it closely matches standard lengths of stock piping. We believe the fabricated units are manufactured under much better quality control and the onsite installations go faster. The turnouts have already been completed, so it's simple to tie them into each floor,” says Holt.

Published in the July/August 2008 issue of Contractor Tools and Supplies magazine.

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