Purchased chilled water utility rates include energy costs, equipment maintenance costs, water costs (for cooling tower make-up), etc. If a proposed design uses purchased chilled water from a utility (as opposed to on site chillers or some other form of cooling capacity on site), are we required to use the published utility rate that includes all of these costs in our energy model? Or are we allowed to work with the utility to determine which portion of their rate is solely for the energy costs?
Use of the published utility rate (including all of the constituent costs) is required for the energy model. Per ASHRAE 90.1-2004, Section G2.4 on Energy Rates: "Annual energy costs shall be determined using either actual rates for purchased energy or state average energy prices published by DOE\'s Energy Information Administration (EIA) for commercial building customers, but rates from different sources may not be mixed in the same project." There is no exception that allows excluding constituent costs other than energy costs. Applicable Internationally.