Granite Tower is a 31-story, Class A office property at 1099 18th Street in Denver. At almost 600,000 square feet, it covers a full city block and is one of the most iconic office properties in the downtown Denver market.

Granite Tower’s cooling system needed an infrastructure update. According to ASHRAE guidelines, the cooling towers, located on the roof, were meant to last 20 years. But at nearly 40 years, the cooling towers and fluid coolers were well past their life expectancy.

At the time of the project, Granite Tower was owned by KBS Real Estate Investment Trust II, one of the largest investors of premier commercial real estate in the nation. Transwestern Real Estate Services and Haynes Mechanical Systems Inc., a commercial HVAC service provider based in Denver, undertook the replacement of the cooling systems on behalf of KBS and the Block 95 Condominium Association.

The three-cell cooling tower serves the entire block’s 1,900-ton cooling needs. The fluid coolers support critical operation rooms, IT closets, and 24/7 data centers within the Granite Tower building.

At 31 stories, the top of the building was too high for a crane to reach. So the teams decided to fly up instead — and in doing so, became the first building in Denver’s central business district to replace aging critical systems via heavy lift helicopter.

Because a lift of this capacity had never been performed in downtown Denver, the team worked closely with the Federal Aviation Administration and the Denver Police Department to establish protocol. The day of the helicopter pick was six months’ worth of coordination coming together.

During the replacement, safety was the top priority — for the 87 participants on-site and the surrounding downtown area. That included traffic redirection and coordination with police the night before to barricade and close down the streets to create a low-fly zone.

At 5:30 a.m., the team held a safety meeting. At first light, the helicopter left the airport and flew over the building to check the wind. It came down, cables were attached, and it started lifting off the old equipment.

The helicopter spent 75 minutes in flight, removing and replacing 50 tons of HVAC equipment, up and down: three cooling tower cells (by Marley, Model NC8405SAN, 6,320 GPM each), two new fluid coolers (Marley, ModelLW0848AF, two cell, 360 GPM each), and two piping headers, amounting to 12 helicopter picks in total. The cooling towers have all new variable frequency drives for the 5 new units.

The system also has two chillers: one existing Trane centrifugal chiller, 900 tons, Model CVHB-095, and one new York centrifugal chiller, 1,000 tons, Model YKNBNRK1-CXGS. Additionally, the project included installation of new valving and an upgrade to the building automation system.

The new towers are much more efficient. They are also slightly larger in capacity so there’s more flexibility for what the building can do in the future.

Photos courtesy of Transwestern.