When the Time & Life Building opened its doors in 1959, steam-turbine-drive chillers provided cooling for the 48-story building at 1271 Avenue of the Americas. An electricity-driven chiller was added in the mid-1980s to supply additional cooling and introduce an alternative-fuel option. Today, the building boasts a one-of-a-kind trifuel plant that uses electric-, steam-, and natural gas-powered chillers to meet increased cooling demands, achieve energy costs savings, and provide redundancy.

The building is owned and managed by the Rockefeller Group Development Corporation, and its primary tenant is Time, Inc., which occupies 1.6 of the building's 1.9 million sq ft and generates enough heat to require constant cooling. William K. Stoddard, vice president of projects and engineering at the Rockefeller Group, enlisted the services of Atkinson Koven Feinberg Engineers LLP (AKF) to help design the plant.

Three is better than one

AKF considered a number of options before selecting the unique trifuel design. "We wanted the owners of the Time & Life Building to be in a good position to take advantage of lower natural-gas rates during peak electric-demand periods and reduce dependency on the electric grid," said John Farrell, partner at AKF.

"We were attempting to do something that had never been accomplished in a New York City high-rise, or anywhere else, for that matter. We were also working within an existing structure, locked into dimensions and configurations that would shape our design. Finally, we needed to find a manufacturer with equipment that suited our design."

"The concept of using a gas engine to drive a compressor or pump has been successfully applied in the oil industry for years. Therefore, we were confident that a York chiller equipped with a Caterpillar engine would produce the required refrigeration capacity and overcome any resistance in the exhaust piping," Farrell said.

The Rockefeller Group selected four York chillers for the Time & Life Building's trifuel plant, including one 2,100 tons of refrigeration (tr) electric-drive chiller, one 1,500 tr steam-turbine-driven chiller, and two 1,850 tr gas-engine-driven chillers.

In addition, York provided one of the gas-engine-driven chillers with an 1,850 tr electric-motor-driven parallel driveline, allowing operators to switch between gas and electric energy sources, depending on which is most economical at a given time. In addition, the second gas-engine-driven chiller has provisions for a parallel electric-motor driveline to be added in the future. The plant also features YorkTalk communication interfaces, linking the chillers to the facility's existing Johnson Controls BAS.

"In the summer, when cooling demands and electric rates are highest, the two gas-engine-driven chillers are the lead chillers. During the winter, when cooling demands are low, we can select a lead chiller based on the most economical fuel source," Farrell said. "We have the additional option of free cooling in the winter, relying on heat exchangers to cool the building using condenser water. The only expense we incur in this process is the cost of pumping water through the pipes."

From Obsolete to Essential

Fresh Meadow Mechanical Corporation installed the plant. Although the building's original system was split between the 47th floor and the basement, plans for the new system called for a single plant located in the basement. In addition to constraints imposed by the existing structure, the creation of an exhaust system challenged engineers and the mechanical contractor. "We were required to vent the exhaust from the natural-gas engines to the roof, 900 ft above the plant," explained Michael Russo, Fresh Meadow's executive vice president.

An obsolete fire shaft, originally intended to draw smoke out of the building, provided a venting shaft from the fourth floor to the roof. Engineers ran an exhaust pipe from each gas-engine-driven chiller, 300 ft across the basement, and up to the fourth floor where the pipes joined in the fire tower.

"We lined the tower with a 24-inch diameter pipe. A stiff-leg derrick on the roof of the building lifted 12 70-foot sections of pipe and lowered them down the shaft to form the exhaust stack," Russo added. "Because the exhaust pipe grows an additional 32 inches when fully heated, we installed pipe guides that accommodate horizontal growth in the basement and vertical growth in the fire shaft." The installation process proceeded with just two scheduled shutdowns.

Over $1 Million in Annual Savings

"We estimated our annual savings in energy costs would be $750,000," Stoddard said. "In actuality, they exceeded $1 million in 2001 and are on track to exceed $1 million again in 2002. These savings are really avoided costs. In other words, if we had not made the changes we made and continued to rely on electricity and steam, our energy costs would have been $1 million more than they are today."ES