518.1 The service water loads for Prototype and Reference Buildings are defined in terms of Btu/h per person in Table 518.1.1, Service Hot Water Quantities. The service water heating loads from Table 518.1.1 are prescribed assumptions for multi-family high-rise residential buildings and default assumptions for all other buildings. The same service water heating load assumptions shall be made in calculating Design Energy Consumption as were used in calculating the Energy Cost Budget.

518.2 The service water heating system, including piping losses for the Prototype Building, shall be modeled using the methods of the RS-47 (incorporated by reference, see § 434.701) using a system that meets all requirements of subsection 404. The service water heating equipment for the Prototype or Reference Building shall be either an electric heat pump or natural gas, or if natural gas is not available at the site, #2 fuel oil. Exception: If electric resistance service water heating is preferable to an electric heat pump when analyzed according to the criteria of § 434.404.1.4 or when service water temperatures exceeding 145 °F are required for a particular application, electric resistance water heating may be used.