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Home My WebLink AboutA comparison of calculated electrical energy use and electrical utility bills A Comparison of Calculated Electrical Energy Use and Electrical Utility Bills Brian Saylor and Associates April 2012 The WHPacific team requested releases of utility bills from individuals and facility managers responding to the survey of electricity consumption. This report summarizes the information collected from electrical utility bills, and compares it with the calculated electrical energy use based on the survey data received from residential and nonresidential respondents. Utility billing information from rural respondents was collected by RurAL CAP as part of the EnergyWise Program. This report summarizes the data from each of these three sectors: residential, nonresidential and rural. Securing Utility Release Forms The number and proportion of respondents who agreed to release their electrical energy utility bills is shown in Table 1. Table 1. Respondents Electrical Utility Bill Releases Residential Non-Residential Number Percent Number Percent Agree 234 73.4 184 61.5 Refuse 85 26.6 115 38.5 319 299 Those individuals who agreed to release their utility bills were given a choice of receiving utility release forms by mail, fax, in person pick up or e-mail. According to their preference, respondents were provided release forms developed by each individual regional utility. The respondents completed the release forms, and submitted them to Craciun Research, WHPacific, or directly to the utility. In some cases, the name on the release form did not match the name of the individual or organization responding to the survey. In other cases, the authorization for utility release included a billing account for which the utility had no information or which the requester had no access authority. This substantially reduced the number of utility release forms yielding complete data that could be linked to the end-use energy calculations. The number of respondents who agreed to provide utility data, the number contacted and the number of successful contacts is shown in Table 2. Table 2. Utility Release Contacts Residential Non-Residential Contacted 234 184 Agreed to provide data 214* 176 Returned release form 45 10 Complete usable data 18 4 *Many respondents were sent a release form by Craciun Research with incentive payment Residential Electrical Energy Use and End-Use Calculations Table 3 presents the basic data on the kilowatt hours shown in utility bills for the 18 respondents for whom complete data was available. All utility data was for a complete calendar year, but the beginning of the year varied by the utility. Chugach electric customers began their calendar year in February 2011. Golden Valley Electric Association and Alaska Electric Light and Power data began in May. Bethel Utilities Corporation furnished monthly average utility costs which were annualized for the entire year. Calculated electrical end-use was taken from Residential Res End Use Calcs v8.xlsx, the data set used in the end-use energy report. The table shows some extreme values in the calculation of electrical energy use that were based on survey data. These values, or "outliers", were eliminated to reduce the impact of extreme values. Table 3. Residential Electrical Energy Use and End-Use Calculations Utility Bills Calculated End Use: CRG KwHrs per Year Cost 5,663 $ 852.12 2,354 19,362 $ 4,272.25 1,790 11,500 $ 2,068.39 9,695 43,296 $ 4,200.00 28,586 14,772 $ 1,837.32 4,180 7,205 $ 1,979.27 2,242 7,051 $ 1,629.87 23,681 2,852 5,010 12,900 6,766 17,473 $ 3,793.58 10,078 6,929 7,744 11,654 18,297 32,136 $ 3,764.64 10,711 3,507 10,441 6,876 $ 921.60 8,487 3,216 $ 482.64 7,730 11,375 8,885 12,065 $ 2,689.20 5,832 Non- Residential Electrical Energy Use and End-Use Calculations Non-residential electrical energy use comparisons employ the same method that was used for residential comparisons. The Non-Residential AK Non Res Survey End Use Results_18_28_12.xlsx was the data source for calculated energy use. As with residential energy use, outliers were identified and eliminated. The data is shown in Table 4. Table 4. Residential Electrical Energy Use and End-Use Calculations Rural Electrical Energy Use and End-Use Calculations All rural observations were from the community of New Stuyahok. The data was collected by RurAL CAP as part of the EnergyWise program. The time of data is from the 12 month period beginning April 2010. This data was compared with similar data also collected through the EnergyWise program, and analyzed by WHPacific. The data was contained in RuralCap End Use Analysis_2-8-12.xlxs. The comparison is shown in Table 5. KwHr Cost Calculated End Use:CRG 170,160 $ 21,477.49 1,825,346 10,156 $ 2,304.80 14,0996 1,117,600 $ 123,515.17 743,855 102,470 $ 9,840.12 47,242 Table 5. Rural Electrical Energy Use and End-Use Calculations KwHr Cost Calculated End Use: CTG 6,630 $ 1,882.57 2,846 4,299 $ 1,160.48 5,595 5,154 $ 1,221.77 5,605 5,361 $ 2,058.77 5,321 2,668 $ 641.38 5,045 2,950 $ 864.89 3,379 2,189 $ 837.69 4,125 7,094 $ 2,051.91 7,117 7,608 $ 2,569.99 4,678 6,422 $ 1,686.47 5,209 5,937 $ 1,447.85 4,099 7,326 $ 2,694.94 5,947 6,480 $ 1,807.23 4,224 6,552 $ 1,761.70 6,121 2,990 $ 710.37 5,764 10,601 $ 5,271.06 6,469 5,801 $ 1,457.94 2,926 5,957 $ 1,647.04 2,452 8,348 $ 3,201.56 9,448 The Correlation Between WHPacific End-Use Energy Data and Utility Records Table 6 shows the results of a correlation analysis of annual kilowatt hours reported by electrical utilities and the kilowatt hours calculated using data generated by a survey conducted by WHPacific. Table 6. The Correlation Between WHPacific End-Use Energy Data and Utility Records N Pearson’s r Correlation Coefficient Significance All Data 41 .482 .001 Outliers Eliminated 24 .983 .000 Even before the elimination of apparent outliers, there is a moderate and statistically significant positive correlation between WHPacific end-use energy data and utility records. The correlation is far higher when outliers are eliminated using a 5% trimmed mean approach.