Hot water delivery systems should meet efficient design requirements (ie. Section 3.3 - EPA WaterSense New Home Specification below)
OR meet criteria for minimum water heater efficiency systems and use WaterSense showerheads and sink faucets. You can find WaterSense Products at epa.gov.
EPA WaterSense New Home Specification
WaterSense has new home specification requirements because heating water is typically the second largest use of energy in a home after space heating and cooling.
- No more than 0.5 gallons of water may be stored in any piping between the hot water source and any hot water fixture.
- To account for the additional water that must be removed from the system before hot water can be delivered, no more than 0.6 gallons of water may be delivered to a fixture before the hot water arrives.
- Recirculation systems must be based on an occupant-controlled switch, an occupancy sensor in each bathroom that is located beyond a 0.5 gallon stored-volume range from the water heater, or ‘adaptive’ scheduling systems that learn the hot water demand profile in a home to adapt their operation. Recirculation systems may not be solely time or temperature-based.