New plant reduces heating, cooling costs
The municipal center complex in Norfolk, Va., is laid out like a campus. Itincludes a City Hall tower and public service building, two court buildings,thepublic safety headquarters and two jail buildings. Additional structures areplanned.
The city’s original central heating and cooling plant provided heat and coolingonly for the City Hall tower and one court building. Other buildings relied onseparate, self-contained systems. After extensive evaluations, the city’sDepartment of Public Works decided last year to enlarge and adapt the centralplant to accommodate the entire expanded complex and future additions.The city hired the Virginia Beach, Va., engineering design firm of Hayes, Seay,Mattern & Mattern to upgrade the system. The firm’s design, which took tophonors in competitions sponsored by the Virginia Consulting Engineers Counciland the Engineers Club of Hampton Roads, replaced the central plant and self-contained systems with an energy-saving chiller and dual-fuel steam boilerfor heating.
Chilled water storage eliminates the environmental and maintenance problemsassociated with chemical refrigerants such as chlorofluorocarbon (CFC).Additionally, electrical chillers cool water at night, so lower off-peak powerrates are incurred. The water is stored in a large, insulated tank for daytimeair conditioning. That thermal storage system alone saves the city about$100,000 per year over conventional, independent air-conditioning systems,according to City Engineer Peter Oberle.
Central plant heating and cooling equipment was reduced in both numbers andcosts. Chilled water thermal storage, with its fewer moving parts andelimination of CFCs, has resulted in higher reliability, less maintenance andlower operating costs, Oberle says.
The chilled water storage system also offers security advantages for jails andcourts. Since most of the mechanical and electrical equipment is located outsidethe secure perimeter, the system minimizes service calls inside the jail’ssecured areas, significantly reducing inmate contact with maintenance personneland their tools and equipment.
Adapting the storage system required the city to find a suitable water storagesite within the city complex, design a storage tank and make extensivealterations to existing building systems. As installed, the tank is unobtrusiveand provides the added benefit of a 1.31 million gallon water reserve forfirefighters in the event of a major fire in or near the complex.
During their re-engineering process, the city’s financial experts concluded thatutility savings alone will enable them to amortize design and installation costsover a few years. The dual-fuel capability of the boiler system also providesthe city with the option of purchasing alternative fuels on the spot market toachieve additional savings.