G/BA provided retro-commissioning services for the existing cooling plant in a 630,000-square-foot art museum in Midtown Manhattan. The museum is currently undergoing a 50,000-square foot-expansion and extensive renovation of gallery spaces,which will increase overall gallery spaces by 30 percent.
G/BA retro-commissioned the museum’s existing cooling plant, which consists of three 850-ton, water-cooled, centrifugal chillers and four cooling towers,which serve approximately 60 air-handling units, 16 fan coil units, and two secondary chilled water loops.
The museum’s expansion and renovation will increase the plant’s cooling load by 453 tons. Conversations with facilities personnel indicated that museum conditions already required operating two chillers at full load, with the third (stand-by) chiller providing N+1 redundancy. These discussions suggested that the plant had already reached its design capacity. By assessing the plant and its equipment, and setting up trends of the plant’s flows and chiller approach temperatures during design-day conditions, G/BA confirmed that added loads from the expansion would require all three chillers to operate, eliminating any redundancy. MoMA elected to expand the plant based onthese investigations.
Pressure profiles were developed for the chilled water coils on several air-handling units to determine whether the existing system’s current differential pressure control set-point of 26 psi was excessive. The data collected revealed the following: