The project, which broke ground in May 2010, was originally slated to finish this fall, but IKEA construction manager Doug Wolfe credits the compressed time line to the coordination efforts performed by Centennial-based Saunders Construction.

“It was a relatively tight site, and there was a lot going on at any given time,” Wolfe says. “At one point we had seven cranes on site, but everything ran smoothly. It also helped that we had a relatively mild winter. Crews were able to finish earlier than originally expected.”

The 415,000-sq-ft store, located along Interstate 25 south of Denver, will be the chain's second largest in the country—despite the 13.5-acre site, which is less than half the size of most IKEA properties. A two-level underground garage was built directly below the store to compensate for the smaller surface footprint, providing nearly all of the 1,500 parking spaces for customers and employees.

The overall design remains true to the signature experience that IKEA is known for worldwide. A walk-through showroom on the upper level—com-plete with three model home interiors and 50 room settings—leads shoppers to a 550-seat restaurant and then down to a self-serve area and warehouse on the lower level.

The store also includes a Swedish food market and concession counter at the checkout area as well as a supervised children's play zone at the main entrance.

But the real showpieces of the construction can't be seen from the showroom floor. Beneath the parking garage is a vertical geothermal field with 130 wells drilled 500 ft deep. Installed on the rooftop is a 498-kilowatt photovoltaic system, the state's largest single-use solar array for commercial purposes.

Geothermal Field

The Centennial store is the first IKEA location in the U.S. to be built with a geothermal heating and cooling system. The system, designed by Castle Rock, Colo.-based Geothermal Systems of Colorado, takes advantage of the near-constant underground temperature of about 55˚F to heat and cool the store.

The technology has been shown to use 25% to 70% less energy than conventional air-source HVAC systems.

As sections of sitework were completed, a crew with Rocky Mountain GeoDrill, also based in Centennial, began drilling the geothermal wells, each 5.5 in. in diameter. Holes were then filled with a U-shaped, high-density polyethylene pipe grouted in place with a bentonite grout and sand mixture, which provides a thermal connection to the surrounding soil or rock to improve heat transfer.

The process, which happened concurrently with foundation, plumbing and drainage work, took about three months to complete and required three mud rotary drill rigs.

Andrew Schmeising, executive director of operations for Geothermal Systems of Colorado, says that to ensure optimal heat transfer, extreme care was taken to install all individual vertical loops at the proper depth with no voids in the grout.