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<br />Page 37 of 38 <br />ATTY/AGR/2017.104/SMART ENERGY SYSTEMS – CUSTOMER WATER USE PORTAL <br />REV: 05-15-17 MI <br />weather data downloaded from specified <br />weather websites. NIR is calculated for both turf <br />and non-turf surfaces, since these surfaces have <br />different water storage characteristics, and thus <br />differing requirements for irrigation. NIR is a <br />function of daily precipitation and daily reference <br />evapotranspiration. <br />IE = <br /> <br />Irrigation Efficiency measures the percent of <br />applied water that is beneficially used by plants. <br />All irrigation systems have some inefficiencies <br />as water is lost as runoff, overspray, or <br />percolates past the root zone. <br />IET or IEN <br />IET = Irrigation Efficiency for Turf (value determined <br />and inputted by Redwood City) <br />i.e. 0.5 to 0.65 <br />IEN = Irrigation Efficiency for Turf default value 0.8 <br />C1 = Conversion factor putting the water budget into <br />gallons. <br />0.623 <br />C2 = Conversion factor putting the water budget in <br />into hundred cubic feet (ccf). <br />748 <br />R = Number of fulltime residents (default = 2, <br />provided by customer and validated by City) <br />2 <br />RW Volume of water allocated to 1 resident per day 57.6 <br />DPP = Days per period is the total days in a billing <br />period/consumption cycle (when calculating a <br />budget for a single day DPP = 1) <br />calculated <br />SN= Special Needs in gallons per day <br /> <br />Net Irrigation Requirement Function: <br />NIRT is calculated for turfgrass using the logic below and the max soil constant for turf. <br />NIRN is calculated for non-Turf using the logic below and the max soil constant for non- <br />turf <br /> <br />NIR(d) = ETo(d) - ERain(d) - SoilStorage(d-1) minimized to 0, where <br />ERain(d) = Min(Precip(d), (MaxSoilConstant + ETo(d) - SoilStorage(d-1))) <br />SoilStorage(d) = Min(MaxSoilConstant, (Precip(d) - ETo(d) + SoilStorage(d-1))) <br />minimized to 0 <br />Precip(d) = Rainfall for day d, measured using tipping bucket rain gauges <br />MaxSoilConstant (turf) = 0.45 inches <br />MaxSoilConstant (non-turf) = 0.90 inches <br /> <br /> <br /> <br />6.1.E. - Page 40