Table : Water Heater Temperature Setback Assumptions Component Unit Values Source , Energy Factor of water heater Fraction EDC data collection 1 Default: Electric Storage= 0.904 HPWH= 2.0 , value of water heater tank, EDC Data Gathering Default: 8.3 50 gal. EDC Data Gathering , value in Surface Area of water heater tank, Default: 24.99 Table 265 , Decimal Electric Storage: 0.98 2, 3 Thermal efficiency of electric heater element (equiv. to COP for HPWH) HPWH: 2.1 , Volume of hot water used per day by gallons/day 7.32 4, 5, 6, 7 clothes washer, in gallons Thot_i , Temperature setpoint of water heater °F 8 EDC Data Gathering initially Default: 130 °F EDC data collection 9 Thot_f , Temperature setpoint water heater after setback Default: 119 ETDF , Energy To Demand Factor (defined 0.00008047 10 above) A The energy savings and demand reductions are prescriptive according to the above formulae. However, some values for common configurations are provided in Table 265 below. Table : Default Energy Savings and Demand Reductions Demand Tank Size Energy Reduction Type (gallons) Savings () (˚F) Electric 50 8.3 24.99 130-119 0.98 0.904 165.9 0.0133 Storage HPWH 50 8.3 24.99 130-119 2.1 2.0 76.2 0.0061 The most appropriate evaluation protocol for this measure is verification of water heater temperature setpoint coupled with assignment of stipulated energy savings. Previous Federal Standards from 2004-2015 are 0.97 -0.00132 x Rated Storage in Gallons. For a 50-gallon tank this is 0.904. Conservation Program: Energy Conservation “Energy Standards for Residential Water Heaters, Direct Heating Equipment, and US Pool Heaters”
Table : Water Heater Temperature Setback Assumptions Component Unit Values Source , Energy Factor of water heater Fraction EDC data collection Default: Electric Storage= 0.904 HPWH= 2.0 1 , value of water heater tank, EDC Data Gathering Default: 8.3 , Surface Area of water heater tank, EDC Data Gathering Default: 24.99 50 gal. value in Table 265 , Thermal efficiency of electric heater element (equiv. to COP for HPWH) Decimal Electric Storage: 0.98 HPWH: 2.1 2, 3 , Volume of hot water used per day by clothes washer, in gallons gallons/day 7.32 4, 5, 6, 7 Thot_i , Temperature setpoint of water heater initially °F EDC Data Gathering Default: 130 8 Thot_f , Temperature setpoint water heater after setback °F EDC data collection Default: 119 9 ETDF , Energy To Demand Factor (defined above) 0.00008047 10 The energy savings and demand reductions are prescriptive according to the above formulae. However, some values for common configurations are provided in Table 265 below. Table : Default Energy Savings and Demand Reductions Type Tank Size (gallons) (˚F) Energy Savings () Demand Reduction Electric Storage 50 8.3 24.99 130-119 0.98 0.904 165.9 0.0133 HPWH 50 8.3 24.99 130-119 2.1 2.0 76.2 0.0061 The most appropriate evaluation protocol for this measure is verification of water heater temperature setpoint coupled with assignment of stipulated energy savings. Previous Federal Standards from 2004-2015 are 0.97 -0.00132 x Rated Storage in Gallons. For a 50-gallon tank this is 0.904. “Energy Conservation Program: Energy Conservation Standards for Residential Water Heaters, Direct Heating Equipment, and Pool Heaters” US A
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