Rating System

LEED O+M: Existing Buildings, LEED O+M: Existing Buildings

Rating System Version

v3 - LEED 2008, v3 - LEED 2009

Inquiry

Cooling to the project building is provided by a district cooling system. The operator of the district cooling system ("Operator") has five chilled water production facilities spread throughout its system with a total capacity of 36,000 tons. One of the five plants contains three 900-ton CFC-based chillers, only two of which can be run simultaneously due lack of cooling tower capacity. The three CFC chillers are the only chillers installed in this plant. Assuming two of the CFC-based chillers are running they are capable of providing 5% of the Operator\'s maximum chilled water production capacity. All five of the Operator\'s chilled water plants are physically interconnected to a common chilled water distribution system. The project building is located directly across the street from the Operator\'s main production facility which contains 54% of the Operator\'s total chilled water production capacity. The project building is one of 49 buildings connected to the district cooling provider\'s system. The peak cooling demand of the project building is 1200 tons. The peak demand for the Operator\'s entire system is 31,000 tons. Hydraulic modeling completed by the Operator shows that due to the project building\'s location on the district cooling system, chilled water produced by the CFC chillers cannot be delivered to the project building except under a single theoretical operating condition. The single operating condition in which chilled water from the CFC-based chillers could theoretically supply the project building would be if the Operator were operating no other chilled water production equipment other than two of the operable CFC chillers. The Operator has stated that since the minimum cooling load of their system exceeds the 1800-ton capacity of the plant containing the CFC chillers by a factor of two or more it would not be possible for the Operator to operate only the plant containing the CFC-based chillers. In order to meet minimum cooling loads additional chillers would have to be operated at one or more of the Operator\'s other production plants. Operating any number of additional chillers at one or more of the other production facilities will create the hydraulic conditions which prohibit chilled water produced by the CFC chillers from supplying the project building. The Operator believes this provides a quantifiable barrier to the project building being supplied chilled water from the CFC-based chillers that would be identical to what would be created by a physical barrier. We are requesting approval of the prerequisite based on the information presented which would be substantiated by submittal of Operator\'s hydraulic modeling results and model verification documentation. Documentation identifying an annual refrigerant leakage rate from the CFC-based chillers of less than 5% would also be submitted.