In new buildings with over 1,000,000 Btu/h installed service water heating capacity serving Group R-1 and R-2 occupancies, at least 25 percent of annual water heating energy shall be provided from any combination of the following water heating sources:
- Renewable energy generated on site that is not being used to satisfy other requirements of this code; or
- Site-recovered energy that is not being used to satisfy other requirements of this code.
Exception: Compliance with this section is not required if the combined input-capacity-weighted average equipment rating for each service water heating fuel source type is not less than the following:
- Electric Resistance: An electric-resistance water heater water with a rating of 105 percent of the rated efficiency of Table C404.2.
- Electric Heat Pump (10 CFR Part 430): A heat pump water heater rated in accordance with 10 CFR Part 430 with a rating of 105 percent of the rated efficiency of Table C404.2.
- Electric Heat Pump (not listed in accordance with 10 CFR Part 430): A heat pump water heater not rated in accordance with 10 CFR Part 430 shall have a COP of not less than 2.0. For air-source heat pump equipment the COP rating will be reported at the design leaving heat pump water temperature with an entering air temperature of 60°F (15.6°C) or less. Supplemental water heaters not meeting the above criteria that function as auxiliary heating only when the outdoor temperature is below 32°F (0°C) or when a defrost cycle is required are not required to have a rated COP of 2.0. Such systems shall be sized and configured to lock out electric resistance or fossil fuel heating from operation when the outdoor temperature is above 32°F (0°C) unless the system is in defrost operation.
- Fossil Fuels: A rated Et of not less than 90% as determined by the applicable test procedures in Table C404.2.
- Hot water heat exchangers used to provide service water heating from a district utility (steam, heating hot water).