Room temperature control in Interchurch center, New York, USA

Thursday, 29 October 2015

The Interchurch Center, located in the Morningside Heights section of New York City’s Upper West Side and managed by Newmark Grubb Knight Frank (NGKF), serves as headquarters for a number of nonprofit organizations. Inspired by the building’s original mission to provide affordable office space and facilitate communication and cooperation among the many religious organizations that would have offices there, John D. Rockefeller, Jr., played a pivotal role in the building’s construction. In addition to gifting the property on which the building sits, he contributed large sums of money to the building fund, along with special monetary gifts earmarked for the cost of the underground garage and the Alabama limestone that encases the structure.

Interchurch Center Case Story

A crowd of more than 30,000 people gathered in 1958 for a cornerstone laying ceremony, which included remarks by then President Dwight D. Eisenhower. The cornerstone, which weighs 2.5 tons, included a carved niche containing a stone from Corinth, Greece, mortared into place by President Eisenhower, and a sealed bronze box filled with a variety of historical documents. Today, the 19-story building, whose construction so many celebrated, houses more than 70 nonprofit organizations, including a wide variety of church agencies, intercultural groups, and community development foundations.

Like many buildings constructed prior to 1970, the Center’s heating, ventilation, and air-conditioning system relies on a two-pipe hot/chilled water changeover system with induction units — some 1,270 of them — to provide the final step in controlling the comfort level and temperature throughout the building. Located beneath every window in the 600,000-square-foot building, the units were nearing the end of their useful life when George D’Amato, the Center’s chief operating engineer, joined the NGKF Engineering Group in 2000. “Our tenants were calling about comfort, especially in the winter when they were too warm,” said D’Amato. “We could turn the heat on and we could turn it off, but our 70 tenants had no way of controlling the temperature in their individual offices. In many cases, they were blasted with heat — a very inefficient use of energy. In addition, the induction units were failing, and the cabinets built around them made it next to impossible to remove them in order to change air filters or adjust the water flow in an effort to improve the room temperature. It required too much manpower and time to remove one cabinet, much less 1,270 of them.”

Updating building’s mechanical systems becomes a priority

D’Amato and the building’s owner realized it was time to address the problem. Fan coil units offered a solution, but it was a costly solution the owner could not afford, given the other capital improvement projects the building’s ownership was planning. Additionally, fan coil units require significant amounts of electrical power, which would increase the building’s utility expense. Instead, the building’s mechanical engineering firm engaged with engineers at Danfoss to develop a more cost-effective solution around the building’s induction system. Meanwhile, work began on the building to update its mechanical systems and create a more comfortable, energy-efficient structure. This work included the installation of two new chillers, four new cooling towers, new electrical panels, a new motor control panel, new windows throughout the Center, and a building-wide lighting retrofit program.

The proposed solution to the problem of aging induction units was an unusual application of three Danfoss products that do not require electricity — the VTA 572 thermostatic diverting valve, the KOVM three-way room temperature control valve, and the RA 2000 room thermostat. The Danfoss VTA is a three-way, nonelectric thermostatic valve that senses the temperature of the supply water and feeds either the chilled water or hot water port of the KOVM room temperature control valve. This particular diverter valve has a low temperature range, providing an ideal control for a two-pipe changeover application, while delivering a cost-effective means to meet application demands. The room temperature control valve, in turn, controls the flow of water to the emitter (or heat exchanger), based on the room temperature requirements as determined by the RA 2000 thermostat setting.
The room temperature setting is easily accomplished by adjusting the dial clockwise or counterclockwise/anticlockwise, using a numbered scale of 1 to 5, corresponding to approximately 57°F to 79°F. Comfort levels are achieved and system efficiency ensured because the control valve package creates a variable flow system which allows the newly installed variable speed pumps to operate at their most efficient point.