In new buildings where the combined input rating of the water-heating equipment installed in a building is equal to or greater than 1,000,000 Btu/h (293 kW), the combined input-capacity-weighted-average efficiency of water-heating equipment shall be no less than the following for each water heating fuel source:
- Electric: A rated 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.
- Fossil Fuel: A rated Et of not less than 90 percent as determined by the applicable test procedures in Table C404.2.
Where not less than 25 percent of the annual service water-heating requirement is provided from any of the following sources:
- 1.1. Renewable energy generated on site that is not being used to satisfy another requirement of this code; or
- 1.2. Site-recovered energy that is not being used to satisfy other requirements of this code.
- Redundant equipment intended to only operate during equipment failure or periods of extended maintenance.
- Electric resistance heated systems installed as part of an alteration where the water heating equipment is installed at the grade level in a building with a height of four stories or greater.
- Hot water heat exchangers used to provide service water heating from a district utility (steam, heating hot water).
- Water heaters provided as an integral part of equipment intended to only heat or boost the heat of water used by that equipment.
- For electric heat systems, supplemental water heaters not meeting this 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.