Overview
The California State University at Long Beach contracted P2S to design a central heating and cooling plant. P2S was also engaged to design, manage and administer a new campus-wide piping distribution system and to retrofit existing building heating and cooling systems to utilize the new central plant. Working as prime consultant, P2S was responsible for project management, engineering, design, construction documents, cost estimates and construction administration.
Challenge
Due to the magnitude and scope of the project, P2S was challenged in many ways. The new central plant required a 50-foot vertical cut in the side of a hill, over two miles of utility trenching through an operating, 40-year old campus including retrofitting and connecting to 45 buildings. The project also provided the opportunity to improve building thermal conditions while substantially reducing campus energy consumption and its carbon footprint.
Action
Central to the project design were numerous energy efficiency measures P2S utilized as the basis for an energy efficient central plant design.
To provide campus cooling, P2S designed a 9,000-ton chiller plant with 34,000 ton-hours of thermal energy storage (TES). To avoid running the electrical chillers at peak periods, yet provide necessary cooling, P2S designed a 34,000 ton-hour thermal energy storage ice tank. Plus, the chiller plant design included 2,000 tons of future capacity.
A 75 MMBtu boiler plant design provided a low-emission, high efficiency heating plant for the campus andcomplied with regulations set by the South Coast Air Quality Management District (SCAQMD). Twelve boilers with heat reclamation were selected to provide a high 70°F∆T, low temperature, 210-140°F, heating hot water system. This provided compatibility with existing building systems and allowed the campus to utilize a more efficient distribution system. The boilers operate at 30 ppm NOx with 84% thermal efficiency. The new plant has reduced campus boiler emissions by 75%.
Primary-secondary pumping was utilized at the central plant to take advantage of variable flow secondary distribution. Campus piping loops were utilized for distribution redundancy and variable speed pumping and two-way valves used in the loops maintained high chilled water temperature differentials. This not only reduced operating costs but also maximized the chilled water pumping performance.
The underground distribution-piping portion of the project utilized approximately nine miles of underground piping with valve pits that allow the campus to isolate pipe sections between valve pits.
The entire plant is fitted with direct digital control and utility metering, including electrical, gas, chilled water and hot water systems for the central plant and all the connected buildings. Plus, all pumps and fans are fitted with variable frequency drives. This energy management system provides reliable operation while minimizing energy consumption.
Results
CSU Long Beach’s new central plant provides the university with efficient and reliable heating and cooling while reducing energy operating costs by more than $1M per year. Plus, the new plant allowed the campus to remove legacy CFC-refrigerant chillers and boilers no longer compliant with the stringent South Coast Air Quality Management Board emission rules.
The new central plant provides more comfortable learning environments by delivering air conditioning to campus buildings previously not conditioned. Working with its client, P2S delivered innovative plant design and control strategies while continuing to work with campus operating personnel to ensure the university leverages all the benefits and features of the new central plant.
