Energy Performance Contractors were asked to develop a scheme for the central chiller plant and distribution system to provide energy savings that would pay for the cost for the project. The Energy Performance Contract was awarded to Con Ed Solutions, Joseph R. Loring & Associates, Inc. (LORING), Morse Diesel, KSW Mechanical and Forest Electric. LORING served as the prime design manager for the mechanical and electrical systems and prepared final design documents for the central chiller plant and site chilled water distribution system. The design included:

• Three 2,000-ton centrifugal chillers with condensing steam turbine prime movers;

• Two 2,000-ton centrifugal chillers with electric motor drives;

• Three 8,000 gpm primary and secondary chilled water pumps;

• Three 11,000 gpm condenser water pumps;

• Eleven 2,000 gpm cooling tower cells, each with a 2-speed fan motor;

• 7,000 linear feet of direct buried chilled water distribution piping.

   

System performance was tested to assure plant efficiency met contract requirements and was capable of achieving the projected energy savings. The system exceeded the projected energy savings.

LORING's design provided the following energy conservation features:

• Variable frequency drive (VFD) electric motor drives on the primary chilled water, secondary chilled water, and condenser water pumps.
• Cooling towers are low rpm type, equipped with special aerodynamic blades to reduce tower fan energy. Eleven 2-speed cooling tower fans are sequenced to match load demand.
• At part load, Brooklyn College may select the form of energy to drive the chillers. Steam for the turbines is produced by gas-fired boilers, permitting the most advantageous energy price (natural gas or electricity) to be selected.
• "Free cooling" is also available for use during the winter months. A study by LORING showed that insulation of the return water mains would save little energy and offer no benefit in terms of payback. Omitting underground return line insulation was also an advantage during winter months by assisting the central "free cooling" system using the ground as a heat sink.