Thermal storage replaces chillers, reduces energy costs
Like many companies across the country, Harleysville Insurance is implementing energy-conservation measures that will help it become “greener” by better managing its energy consumption and, over time, reducing its overall energy costs. While the company has taken steps, such as reducing the electricity it uses for lighting, computers, and other electronic equipment and expanding its recycling efforts, a more significant green initiative revolves around the recent replacement of the outdated chiller plant in its home office in Harleysville, Pa., with a new thermal-storage solution designed to optimize energy savings.
Harleysville's headquarters facility is a two-story office building comprising about 220,000 usable square feet and accommodating some 900 full- and part-time employees. The original part of the complex was constructed in 1950, with three additions built over the years (the most recent in 1989) to accommodate the company's steady growth.
The company has had a long-standing relationship with Tozour-Trane, a division of Tozour Energy Systems Inc., King of Prussia, Pa., an HVAC and building-automation provider. Based on the age of the Harleysville building's HVAC systems, coupled with pending utility deregulation expected to increase energy costs by 20 percent or more in 2011, Tozour recommended that the company upgrade its existing infrastructure and controls to save on energy consumption and costs.
“We were impressed by the initial facility survey performed by Tozour Energy Systems to review our existing building conditions and infrastructure,” Andy Shields, assistant secretary and director of facilities for Harleysville Insurance, said.
After an engineering review of the facility, Tozour proposed replacing the building's existing chiller plant with a new thermal-storage solution designed to optimize the company's energy savings. Lighting and air-handling-system control upgrades also were suggested to provide a more efficient and comfortable environment for the company's employees.
“One of the challenges was finding a solution with the right mix of energy-conservation measures to balance payback based on the age of the facility and pending utility-deregulation cost increases,” Lew Ischinger, account manager for Tozour Energy Systems, said. “Through our flexible delivery system, Harleysville was able to determine which energy-conservation measures (ECMs) provided the ultimate savings and payback.”
Tozour-Trane partnered with Concord Atlantic Engineering and Innovative Energy Solutions to provide the turnkey solution to Harleysville Insurance.
The chiller-plant project consisted of the replacement of two chlorofluorocarbon chillers with a new Trane helical rotary chiller, the rebuilding and renovation of a Trane centrifugal chiller, and the installation of a Calmac thermal-storage system to “load shift” electrical consumption.
“The new system produces ice during off-peak hours, when electricity rates are significantly lower, which reduces the client's overall utility costs,” Ischinger said. “During the daytime hours, the ice is melted to produce chilled water for the building's comfort-cooling needs.”
Additionally, a facilitywide lighting upgrade was performed to install motion sensors and more-energy-efficient bulbs and ballasts. Existing air-handling units were upgraded to include variable-frequency drives with enhanced space pressurization and controls to provide increased efficiency and employee comfort.
“The key to the project's success was the close supervision by Chick Winner, Harleysville's building services manager,” Ischinger commented. “Chick provided valuable day-to-day input and site coordination of the work progress.”
According to Ischinger, one of the most unique aspects of this project is the physical location of the ice-storage tanks.
“Our original plan was to put all of the equipment out of sight in the company's mechanical room,” Ischinger said. “But Andy Shields suggested that the tanks be installed outdoors so the company could showcase this important green initiative before its employees and visitors.”
The ice tanks are visible in a courtyard outside a corridor near the building's cafeteria. Accompanying signage provides a brief overview of how the system works and the efficiencies it offers Harleysville.
The work at Harleysville Insurance was completed during the fall of 2009. With the new ice tanks, Tozour shifted more than 300 kw of demand from peak times in the early afternoon, when the electrical grid is stretched to capacity, to after midnight, when the grid is relaxed and there is an excess of electrical capacity.
Based on preliminary estimates, the project is expected to generate energy savings representing more than 1,900 tons of carbon avoided, which is the equivalent of planting more than 9,500 trees.
“To date, the new ice-tank storage system has significantly reduced our consumption of peak daytime energy usage and the associated costs,” Shields said. “We are definitely pleased with the energy-saving results so far, along with the more comfortable environment we've been able to provide our employees. We feel that the engineering approach in regard to initial calculation of the savings of each ECM, in coordination with the survey data, has played a key role in our ability to meet our energy conservation and cost-saving objectives.”
Information and photographs courtesy of Tozour-Trane.
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