The load shapes (fractions of annual energy usage that occur within each hour) during summer week days are plotted in Figure 211 below. Figure : Load shapes for hot water in residential buildings taken from a PJM study. Definition of Terms The parameters in the above equation are listed in Table 295 below. Table : Water Heater Temperature Setback Assumptions Component Type Values Source , Energy Factor of water heater Variable EDC data collection 1 Default Electric Storage 0.904 – HPWH 2.0 – , R value of water heater tank, Variable EDC data collection Default: 8.33 Variable EDC data collection Default: 24.99 50 gal. value in , Surface Area of water heater tank, Table 293, Section 2.38 , Thermal efficiency of electric heater Fixed Electric Storage- 0.97 2, 3 element (equiv. to COP for HPWH) HPWH- 2.1 , Volume of hot water used per day, in Fixed 7.32 gallons/day 4, 5, 6, 7, 8 gallons Thot_i, Temperature setpoint of water Variable EDC data collection 9 heater initially Default: 130°F Variable EDC data collection 10 Thot_f, Temperature setpoint water heater after setback Default: 123 °F Energy To Demand Factor Fixed 0.00008294 11-13 Sources: Federal Standards are 0.97 -0.00132 x Rated Storage in Gallons. For a 50-gallon tank this is 0.904. Conservation Program: Energy Conservation Standards for “Energy Residential Water Heaters, Direct Heating Equipment, and Pool US Dept of Heaters” Energy Docket Number: EE–2006–BT-STD–0129, p. 30 New York Standard Approach for Estimating Energy Savings from Energy Efficiency Programs. October 15, 2010. Prepared by New York Advisory Contractor Team.
The load shapes (fractions of annual energy usage that occur within each hour) during summer week days are plotted in Figure 211 below. Figure : Load shapes for hot water in residential buildings taken from a PJM study. Definition of Terms The parameters in the above equation are listed in Table 295 below. Table : Water Heater Temperature Setback Assumptions Component Type Values Source , Energy Factor of water heater Variable EDC data collection 1 Default Electric Storage – 0.904 HPWH – 2.0 , R value of water heater tank, Variable EDC data collection Default: 8.33 , Surface Area of water heater tank, Variable EDC data collection Default: 24.99 50 gal. value in Table 293, Section 2.38 , Thermal efficiency of electric heater element (equiv. to COP for HPWH) Fixed Electric Storage- 0.97 HPWH- 2.1 2, 3 , Volume of hot water used per day, in gallons Fixed 7.32 gallons/day 4, 5, 6, 7, 8 Thot_i, Temperature setpoint of water heater initially Variable EDC data collection 9 Default: 130°F Thot_f, Temperature setpoint water heater after setback Variable EDC data collection 10 Default: 123 °F Energy To Demand Factor Fixed 0.00008294 11-13 Sources: Federal Standards 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 Dept of Energy Docket Number: EE–2006–BT-STD–0129, p. 30 New York Standard Approach for Estimating Energy Savings from Energy Efficiency Programs. October 15, 2010. Prepared by New York Advisory Contractor Team.
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