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Residential Electric and Gas Customer Usage and Expenditure Analysis: City of Wilson, NC

Jennifer Weiss Yijing Cheng

June 2014

Residential Electric and Gas Customer Usage and Expenditure Analysis

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About the Environmental Finance Center The Environmental Finance Center at the University of North Carolina, Chapel Hill is part of a network

of university-based centers that work on environmental issues, including water resources, solid waste

management, energy, and land conservation. The EFC at UNC partners with organizations across the

United States to assist communities, provide training and policy analysis services, and disseminate

tools and research on a variety of environmental finance and policy topics.

The Environmental Finance Center at the University of North Carolina, Chapel Hill is dedicated to

enhancing the ability of governments to provide environmental programs and services in fair, effective,

and financially sustainable ways.

Acknowledgements Written by Jennifer Weiss and Yijing Cheng.

The authors of this report would like to thank the City of Wilson for their support and assistance with

this project – specifically Bob Arrington, Drenda Carpenter and Jennifer Cawthon from Wilson Energy

as well as Randy Faircloth, the Wilson County Tax Administrator. Editorial assistance was provided by

Alexandra Kay.

This report is a product of the Environmental Finance Center at the University of North Carolina, Chapel

Hill. Findings, interpretations, and conclusions included in this report are those of the authors and do

not necessarily reflect the views of EFC funders, the University of North Carolina, the School of

Government, or those who provided review.

We are grateful to the Z. Smith Reynolds Foundation for funding this research.

Cover photo courtesy of Chris Dixon under Creative Commons Attribution ShareAlike license.

© 2014 Environmental Finance Center

at the University of North Carolina, Chapel Hill

School of Government

Knapp-Sanders Building, CB# 3330

University of North Carolina at Chapel Hill

Chapel Hill, NC 27599-3330

http://efc.sog.unc.edu

All rights reserved

http://efc.sog.unc.edu/


Environmental Finance Center at the University of North Carolina | 2

TA B L E O F C O N T E N T S

Executive Summary 3

Research Objectives 4

Methodology 4

Residential Electric and Gas Customer Profiles 6

Residential Electric and Gas Customer Consumption Analysis

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Energy Intensity Analysis 13

Pete Street Program Analysis 16

Target Groups for Energy Efficiency 17

Potential Next Steps 17


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E X EC UT I VE S U MM A R Y

Expenditures on energy, particular electricity, are a necessity for most homeowners. In the City of Wilson, North Carolina, residential customers spend an average of approximately $146 each month on electricity. This equates to an annual electricity expenditure of roughly 4.8 percent of the City’s Median Household Income of $36,469,1 higher than the nation’s average of 2.7%.2 In order to assist the City of Wilson’s Utility Department in gaining a deeper understanding into their residential customers’ electric and gas usage and expenditures, the Environmental Finance Center at the University of North Carolina at Chapel Hill (EFC) used the City’s utility billing data, as well as tax parcel data from Wilson County, to analyze the utility’s residential electricity and gas accounts by usage and expenditure characteristics. According to this analysis, the following key observations and customer groups emerge: Observation 1: On average, the amount of electricity usage (kWh) and expenditures ($) decreased between FY11 and FY12 and remained constant in FY13.

Electricity Usage FY11

(Jan – Dec 2011)

FY12

(Jan – Dec 2012)

FY13

(Jan – Dec 2013)

Number of Premise Accounts 29,974 29,984 30,033

Mean Usage (kWh/month) 1,115 1,051 1,053

Mean Bill ($/month) $158.68 $146.06 $146.44

Observation 2: 42 percent of the City’s electricity customers also use natural gas. On average, the amount of natural gas usage (CCF) and expenditures ($) decreased between FY11 and FY12, but increased in FY13.

Natural Gas Usage FY11

(Jan – Dec 2011)

FY12

(Jan – Dec 2012)

FY13

(Jan – Dec 2013)


Mean Usage (CCF/month) 43.40 34.63 41.66

Mean Bill ($/month) $57.54 $47.76 $55.44

Observation 3: Based on our analysis of high consumption and high energy intensity households, we are able to identify premise accounts with particularly high energy use patterns indicative of potential problems. These premise accounts include the following sub-groups:

2,889 “super users” of electricity (over 2,000 kWh on average each month).

721 accounts with “high to super high” average energy intensity (over 1.5 kWh per month per

square foot).

309 accounts with overlap – both a “super user” of energy and “high to super high” energy intensity.

15 accounts with “high to super high” summer intensity and “low” winter intensity.

The following analysis details the energy usage and expenditures of each of these subgroups and offers recommendations that can be used by the City of Wilson to target specific residential customers that might benefit from energy efficiency improvements to their homes.

1 United States Census Data, American Fact Finder, http://factfinder2.census.gov, accessed 12/3/13. 2 U.S. Energy Information Administration, http://www.eia.gov/todayinenergy/detail.cfm?id=10891, accessed 2/18/14.

http://factfinder2.census.gov/

http://www.eia.gov/todayinenergy/detail.cfm?id=10891



RESEARCH OBJECTIVES

North Carolina electricity rates and the resulting consumer electricity expenditures impact a wide range of critical community and economic development issues in the state. Local municipal utilities must navigate a balancing act to ensure they have the revenue necessary to maintain safe and reliable service without imposing excessive financial hardship on their customer base. The EFC was asked to assist the City of Wilson, North Carolina’s utility department in analyzing the usage and expenditure trends of its 30,000 residential electric customers (including 12,880 gas and electric customers). The objective of this analysis is to collect and analyze residential customer electricity and gas rates, usage, expenditure, and property data in order to:

1. Identify the need and size of the market for energy efficiency initiatives; 2. Expand the understanding of the City’s residential electricity and gas usage and expenditure profiles and

usage, particularly among economically vulnerable populations; 3. Evaluate the customer level impact of past energy efficiency initiatives, including Clean Energy Durham’s

Pete Street® Program, and determine which customer groups have the most room for efficiency gains; 4. Assist utility managers and local officials in meeting their revenue and management goals (e.g. revenue

stability, conservation, affordability) by strengthening their ability to identify and predict customer usage and behavioral patterns and the resulting revenue impact.

Through an analysis of bill payment records from the utility and property data from the Wilson County Tax Administrator’s office, certain trends and customer groups emerge that can be used by the City of Wilson to target specific residential customers that might benefit from energy efficiency improvements.

METHODOLOGY

This research was conducted using utility billing records from Wilson Energy, the city’s utility department. The records covered the time frame from January 2011 through December 2013 (36 consecutive months). The EFC used Wilson Energy’s electricity and natural gas billing data and tax parcel data from Wilson County to analyze the utility’s residential electricity accounts by usage and expenditure characteristics. In this analysis, we assign accounts to various groups based on consumption patterns and housing characteristics in order to provide the City of Wilson with a comprehensive segmentation of their residential electricity and gas customers. This analysis develops metrics for premise accounts that are consistently high users of energy and focuses specifically on the premise accounts that have a high energy use intensity (defined as kilowatt hours per square foot of

heated space). For energy intensity comparison purposes, the natural gas usage was converted from CCF to kWh. For this analysis, we have used the following definitions throughout this report:

A “Billing Record” is a summary of the monthly transactions for each residential electric meter. It includes billing account number, tenant number, service address, electric usage (kWh), natural gas usage (CCF) and total bill amount ($).

A “Bill Payer” is the person (or business) that is required to pay the bill. In Wilson’s case, this is tracked by the “customer id” which changes with each change in bill payer. This can be used to track turnover in the Wilson housing stock.

A “Premise Account” is a combination of billing records and bill payers for one address. It represents all activity for each individual electric meter.


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In this study, we began with a complete set of utility billing records from the City’s electric department and tracked each individual premise account’s electricity and natural gas use over a 36-month period. We then developed categories based on usage behavior in order to provide the City with a more refined view of their customer base. Lastly, we identified premise accounts with particular usage characteristics that the City could target with energy efficiency programs. In particular, we identified premise accounts with abnormally high energy usage that could benefit from an energy audit and weatherization upgrades. In addition, accounts with high summer or high winter use might be candidates for heating, ventilation and air conditioning upgrades. The City of Wilson has participated in the Pete Street® program, an energy efficiency education program administered by Clean Energy Durham. Pete Street® is a neighbor-to-neighbor energy training program designed to help municipalities, utilities and community organizations promote residential energy efficiency savings. From September 2012 through August 2013, the City of Wilson held 36 different community training sessions with 228 single family residential participants. This report will analyze the usage characteristics of the Pete Street® participants in an effort to measure the results of the program. The EFC received a billing file containing 1,195,564 individual billing records that include monthly electricity and natural gas usage data for the utility’s residential electric and natural gas customers – a total of 35,305 different single family, multi-family and commercial accounts – for the entire 36-month period between January 2011 and December 2013. In order to maintain confidentiality, all personally identifiable information for each bill payer was removed from the file and the resulting file (and all associated data analysis) is housed on the University’s secure servers. In addition, we performed the following data cleaning techniques:

Flagged accounts that had zero usage during any month.

Combined billing records that had multiple bill payers associated with one service address. These billing

records were combined into one premise account.

Combined billing records that had duplicate addresses for individual meters. These billing records were

combined into one premise account.

Using an identifier found on both the utility and the property data files (Parcel ID), we merged the utility billing file with the county property data. These premise accounts include both single- and multi-family residential accounts as well as owner-occupied and rental units.

Each property in the county records had a “parcel type” which was used to remove multi-family and commercial properties from the file. This resulted in 29,974 residential premise accounts in 2011 (January through December 2011), 29,984 residential premise accounts in 2012 (January through December 2012) and 30,033 residential premise accounts in 2013 (January through December 2013).

The following analysis is based on the data set that remained after the data cleansing and the merging of utility billing records with the county data file. It was used to perform three types of analysis for the City of Wilson’s residential electric and gas utility accounts:

1. Energy consumption and expenditure analysis 2. Energy use intensity analysis (kwh per month per square foot of building area) and 3. Energy consumption analysis for residential households that have received energy efficiency training

through Clean Energy Durham’s Pete Street program.

This report summarizes the results of these analyses and provides the City of Wilson with an in-depth understanding of their residential electric and gas customers’ usage and expenditures.



RESIDENTIAL ELECTRIC AND NATURAL GAS CUSTOMER PROFILES

C I T Y O F W I L S O N O V E R V I E W

The City of Wilson is the county seat of Wilson County in the Coastal Plain region of North Carolina. It is

considered a “moderate” region with average temperatures of 88 degrees Fahrenheit in the summer months

and 55 degrees Fahrenheit in winter months.3 According to U.S. Census data, the population of the city in 2012

was 49,610 with 19,585 households.4

Table 1: Town Demographics

2012 CENSUS DATA CITY OF WILSON WILSON COUNTY NORTH CAROLINA

POPULATION 49,610 81,867 9,544,249

MEDIAN HOUSEHOLD INCOME $36,469 $38,398 $46,450

NUMBER OF HOUSING UNITS5 21,670 35,428 4,325,088

MEDIAN HOUSE VALUE $133,600 $114,200 $153,600

PERCENTAGE OWNER-OCCUPIED 49.5% 60.0% 67.1%

PERCENTAGE RENTAL 50.5% 40.0% 32.9%

PERCENTAGE ELECTRIC HEAT 49.5% 51.6% 58.3%

PERCENTAGE GAS HEAT 46.7% 33.9% 25.0%

PERCENTAGE PROPANE HEAT 1.4% 10.6% 8.9%

Source: United States Census Data, American Fact Finder

W I L S O N E N E R G Y

Wilson Energy, the city’s electric and natural gas utility, serves approximately 30,000 residential premise

accounts in a territory that includes the town and surrounding communities. Of these accounts, 58 percent are

electric only customers and the remaining 42% have gas and electric service.

The city has one year-round residential electric rate. The current rate (RES92) has been in effect since February

2012:

ELECTRIC RES91 (July 2010 – January 2012) RES92 (February 2012 – present)

Base Monthly Charge ($) $10.00 $10.00

Energy Charge ($/kWh) $0.135 $0.131

3 Monthly average temperatures for Wilson, NC provided by The Weather Channel, http://www.weather.com/weather/wxclimatology/monthly/graph/USNC0761, accessed 4/22/14. 4 United States Census Data, American Fact Finder, http://factfinder2.census.gov, accessed 4/22/14. 5 The United States Census defines a “housing unit” as a house, an apartment, a mobile home or trailer, a group of rooms, or a single room that is occupied, or, if vacant, is intended for occupancy as separate living quarters. http://www.census.gov/popest/about/terms/housing.html, accessed 12/20/13.

http://www.weather.com/weather/wxclimatology/monthly/graph/USNC0761

http://factfinder2.census.gov/

http://www.census.gov/popest/about/terms/housing.html


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The City has one year-round residential natural gas rate, although it is variable for usage that exceeds 5 CCF per

month. The current rate (Amendment 132, Schedule A) has been in effect since February 2012:

NATURAL GAS Amendment 131, Schedule A

(November 2010 – January 2012)

Amendment 132, Schedule A

(February 2012 – present)

Base Monthly Charge ($) $10.00 $10.00

Energy Charge – Up to 5 CCF $1.265 $1.202

Energy Charge – All over 5 CCF $1.204 $1.144

The City purchases 100 percent of its electricity wholesale from the North Carolina Eastern Municipal Power

Agency (NCEMPA). Approximately 80 percent of the City’s revenue from retail electricity sales is paid to

NCEMPA for wholesale purchases and the remaining 20 percent goes towards operation and maintenance of the

distribution system.

R E S I D E N T I A L E L E C T R I C I T Y A G G R E G AT E C O N S U M P T I O N P R O F I L E

The City of Wilson’s billing file for 2011, 2012 and 2013 (the 36 month period from January 2011 through December 2013) includes monthly electricity usage and customer bill information for 29,974 premise accounts in 2011, 29,984 premise accounts in 2012 and 30,033 premise accounts in 2013. The average monthly kilowatt usage and monthly bill for each year are summarized in Table 2 below:

Table 2: Residential Electricity Consumption and Expenditure Profile (all premise accounts)

From billing records for the entire fiscal year (January – December)

2011 2012 2013


Mean Usage (kWh/month) 1,115 1,051 1,053

Median Usage (kWh/month) 957 923 920

Mean Bill ($/month) $158.68 $146.46 $146.44

Median Bill ($/month) $137.85 $130.15 $129.47

The consumption and expenditure profile above indicates that, at an aggregate level, the average monthly electricity consumption for residential households decreased slightly between 2011 and 2012, but has remained relatively steady through 2013. Average monthly electricity expenditures decreased over the same period. When broken down by monthly usage (Table 3), the months with the highest usage and expenditure in all years occur during the summer (July – September) and winter (January – March) months. A key takeaway from the monthly comparison in Table 3 is that each month there is a variation in usage and expenditure, indicating that weather has a significant impact. This can make predicting usage and savings from energy efficiency improvements difficult in the residential market –an important consideration when developing an energy efficiency loan program because the monthly loan payment might not always be less than or equal to the actual reduction in energy expenditures in any given month due to fluctuations in weather patterns.



Table 3: Monthly Comparison of Electricity Usage and Bill Amount

During the summer months, electricity usage averaged 1,234 kWh monthly with an average monthly bill of $168.38. During the winter months, average electricity usage was 1,182 kWh across all customers with an average monthly bill of $163.06. In addition to electric utility bills, a subset of the City’s residential electricity customers (42 percent) also use natural gas for heat and hot water. The City of Wilson’s billing file for 2011, 2012 and 2013 includes monthly natural gas usage and customer bill information. The average monthly usage (in centum cubic-feet or CCF) and monthly bill for each year are summarized in Table 4 below: Table 4: Residential Natural Gas Consumption and Expenditure Profile (all premise accounts) From billing records for the entire fiscal year (January – December)

2011 2012 2013

Number of Gas Premise Accounts 12,691 12,702 12,754

Mean Usage (CCF/month) 43.40 34.63 41.66 Median Usage (CCF/month) 13.70 13.00 15.13

Mean Bill ($/month) $57.54 $47.76 $55.44 Median Bill ($/month) $24.75 $24.02 $25.30

The consumption and expenditure profile above indicates that at an aggregate level, the average monthly natural gas consumption for residential households decreased by 20 percent between 2011 and 2012, but rose again in 2013. When broken down by monthly usage (Table 5), the months with the highest usage and expenditure occur during the winter (December – April) months.

MONTH

MEAN USAGE (KWH/MONTH)

MEAN BILL AMOUNT ($/MONTH)

2011 2012 2013 2011 2012 2013 JANUARY 1,557.81 1,122.02 1,192.42 $217.55 $159.71 $164.21 FEBRUARY 1,315.37 1,108.78 1,241.05 $185.25 $154.39 $170.74 MARCH 964.76 994.68 1,113.17 $138.61 $138.75 $154.24 APRIL 838.56 774.88 960.11 $121.79 $110.29 $134.47 MAY 752.81 816.14 757.14 $110.34 $115.68 $108.20 JUNE 1,087.42 962.90 1,013.68 $154.90 $134.67 $141.39 JULY 1,373.45 1,353.29 1,276.13 $193.35 $185.11 $175.18 AUGUST 1,540.31 1,482.59 1,261.54 $215.53 $201.85 $173.11 SEPTEMBER 1,302.16 1,230.06 1,134.60 $183.31 $169.17 $156.90 OCTOBER 909.56 859.72 827.24 $131.34 $121.26 $117.12 NOVEMBER 805.41 943.00 807.81 $117.40 $132.14 $114.65 DECEMBER 936.90 962.38 1,059.73 $134.92 $134.51 $147.27


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Table 5: Monthly Comparison of Natural Gas Usage and Bill Amount MONTH

MEAN GAS USAGE (CFF/MONTH)

MEAN GAS BILL AMOUNT ($/MONTH)

2011 2012 2013 2011 2012 2013 JANUARY 146.37 80.84 85.92 $73.58 $42.21 $44.81 FEBRUARY 125.97 83.79 104.07 $64.05 $43.68 $53.36 MARCH 71.67 70.88 94.78 $38.34 $37.65 $49.12 APRIL 49.26 23.68 69.05 $27.58 $15.34 $36.89 MAY 13.81 16.40 19.38 $10.74 $11.91 $13.33 JUNE 6.09 5.91 8.23 $7.01 $6.89 $8.02 JULY 4.54 4.51 4.73 $6.23 $6.19 $6.31 AUGUST 4.21 4.15 3.71 $6.04 $6.01 $5.80 SEPTEMBER 4.68 4.63 3.92 $6.23 $6.22 $5.87 OCTOBER 7.07 7.72 6.06 $7.38 $7.67 $6.86 NOVEMBER 29.34 43.02 26.91 $17.84 $24.12 $16.63 DECEMBER 52.51 68.01 69.18 $28.86 $36.21 $36.56 As can be seen in Tables 3 and 5, one of the most influential impacts on electricity and natural gas usage is the impact of weather conditions – specifically the impact of outside air temperatures. In the summer months when temperatures are high, customers with electric air conditioning units may experience a spike in electricity usage. Conversely, in winter months when temperatures drop, customers with electric heating appliances will use more electricity in order to heat their homes, while customers with natural gas heating appliances will use more natural gas. This trend can be seen in Figure 1 below which tracks overall monthly electricity and natural gas usage together (CCFs have been converted to kWh for ease of comparison).

Figure 1: Total Monthly Electricity and Natural Gas Consumption (All Accounts)



RESIDENTIAL ELECTRIC AND GAS CUSTOMER CONSUMPTION ANALYSIS

A V E R A G E M O N T H LY C O N S U M P T I O N A N A LY S I S

To better understand consumption on an individual account level, the usage patterns of each premise account were analyzed to identify trends and group accounts according to their average monthly consumption of electricity. In the following analysis, each premise account is placed into a usage group based on average monthly electricity usage. These groups are defined as follows:

Zero Consumption 0 kWh per month Low Consumption 1 – 500 kWh per month Low-Mid Consumption 501 – 1,000 kWh per month High-Mid Consumption 1,001 – 1,500 kWh per month High Consumption 1,501 – 2,000 kWh per month Super High Consumption > 2,000 kWh per month

Table 6: Average Monthly Consumption Breakdown (Electricity Only) Volume category based on premise account’s average monthly usage Consumption Group Number of Accounts Total Usage (in kWh)

2011 2012 2013 2011 2012 2013

Zero (0) 164 154 129 0 0 0 Low (1-500) 3,845 4,260 4,410 12,511,955 14,341,959 14,961,467 Low-Mid (501 – 1,000) 10,341 11,322 11,398 90,818,207 99,229,066 99,916,947 High-Mid (1,001 – 1,500) 9,237 8,985 8,692 132,416,498 128,027,109 124,462,945 High (1,501 – 2,000) 4,436 3,781 3,750 89,059,866 75,548,055 75,219,468 Super High (> 2,000) 1,952 1,482 1,654 55,835,586 42,694,082 47,284,178

TOTAL 29,974 29,984 30,033 380,642,112 359,840,271 361,845,005

Table 7: Average Monthly Consumption as a Percentage of Total Consumption (Electricity Only) Volume category based on premise account’s average monthly usage Consumption Group % of Total Accounts % of Total Usage (kWh)

2011 2012 2013 2011 2012 2013

Zero (0) 0.54% 0.51% 0.43% 0% 0% 0% Low (1-500) 12.3% 14.21% 14.68% 3.29% 3.99% 4.13% Low-Mid (501 – 1,000) 34.50% 37.76% 37.95% 23.86% 27.58% 27.61% High-Mid (1,001 – 1,500) 30.82% 29.97% 28.94% 34.79% 35.58% 34.40% High (1,501 – 2,000) 14.80% 12.61% 12.49% 23.40% 20.99% 20.79% Super High (> 2,000) 6.51% 4.94% 5.51% 14.67% 11.86% 13.07%

Since a large portion of the City’s electric customers also use natural gas for heat and hot water, the total energy usage of the residential customers should be taken into account. For comparison purposes, the natural gas usage was converted from CCF to kWh. Total energy usage for the City of Wilson households can be found below in Tables 8 and 9.


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Table 8: Average Monthly Consumption Breakdown (Electricity and Gas) Volume category based on premise account’s average monthly usage Consumption Group Number of Accounts Total Usage (in kWh)

2011 2012 2013 2011 2012 2013

Zero (0) 161 153 126 0 0 0 Low (1-500) 3,246 3,691 3,670 10,114,061 12,053,275 11,945,939 Low-Mid (501 – 1,000) 9,650 10,856 10,853 85,157,793 95,783,872 95,874,769 High-Mid (1,001 – 1,500) 9,795 9,512 9,413 140,852,302 136,024,552 135,217,476 High (1,501 – 2,000) 4,904 4,129 4,109 98,584,872 82,649,644 82,621,276 Super High (> 2,000) 2,218 1,643 1,862 63,947,524 47,685,447 53,514,270

TOTAL 29,974 29,984 30,033 398,656,552 374,196,790 379,173,730

Table 9: Average Monthly Consumption as a Percentage of Total Consumption (Electricity and Gas) Volume category based on premise account’s average monthly usage Consumption Group % of Total Accounts % of Total Usage (kWh)

2011 2012 2013 2011 2012 2013

Zero (0) 0.54% 0.51% 0.42% 0.00% 0.00% 0.00% Low (1-500) 10.83% 12.31% 12.22% 2.54% 3.22% 3.15% Low-Mid (501 – 1,000) 32.19% 36.21% 36.14% 21.36% 25.60% 25.29% High-Mid (1,001 – 1,500) 32.68% 31.72% 31.34% 35.33% 36.35% 35.66% High (1,501 – 2,000) 16.36% 13.77% 13.68% 24.73% 22.09% 21.79% Super High (> 2,000) 7.40% 5.48% 6.20% 16.04% 12.74% 14.11%

Although the total number of accounts remained about the same in all three years, the number in the High and Super High consumption groups decreased by 19 percent between 2011 and 2012 and increased slightly (by 3.4 percent) in FY13. In 2011, 24 percent of accounts had high to super-high levels of energy consumption, decreasing to 20 percent – 5,971 accounts – in 2013. The premise accounts in these consumption groups are a potential target group for the energy efficiency loan programs under development by the City of Wilson.

Figure 2: Number of Premise Accounts for Each Consumption Group for 2011, 2012 and 2013



S I N G L E FA M I LY R E S I D E N T I A L P R O P E R T Y D ATA

Using data supplied by the Wilson County tax department, the EFC was able to match 22,663 of the utility’s

30,033 premise accounts (75 percent) with property statistics from single family residences including square

footage, age of building, appraised value and type of heating source. Of the matched accounts, 21,024 had non-

zero data populated in the fields. Because the property data was provided at the building level (mutli-family

housing units included only aggregate square footage and appraised values), this analysis used only property

data from single family residences. The combined data provides a more granular view of the characteristics of

accounts that fall into each of the consumption groups:

Table 10: Average Square Footage, Age of Home and Appraised Value for Each Consumption Group Volume category based on single family premise account’s average monthly usage

Consumption Group Number of Accounts

Average Square

Footage Average Age of Home (years)

Average Appraised Value

Zero (0) 41 1,220 71 $174,005

Low (1-500) 1,946 1,388 52 $106,149

Low-Mid (501 – 1,000) 7,385 1,471 43 $115,882

High-Mid (1,001 – 1,500)

7,083 1,714 36 $136,233

High (1,501 – 2,000) 3,211 1,980 32 $158,879

Super High (> 2,000) 1,358 2,578 31 $220,493

TOTAL 21,024 1,694 39 $135,275

About 6 percent of the houses fall into the Super High consumption group, but many of these are very large (average square footage is 2,578 sq. ft.) and would understandably use more energy for heating and cooling. Figure 3 shows the distribution of finished area for the Super High consumption group.

Figure 3: Distribution of Finished Area for Super High Consumption Group

Finished Area (sq. ft.)

Distribution of Finished Area for “Super high” Consumption Group


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ENERGY INTENSITY ANALYSIS

While overall energy usage is an important consideration for accounts with high energy bills, it is even more

important to consider the energy intensity of a home – measured in kilowatt hours per month per square foot –

when identifying groups of accounts to target for energy efficiency improvements. According to data provided

by the U.S. Energy Information Administration, the average monthly energy intensity for a residential single

family home in North Carolina is 1.01 kWh per square foot.6 For the City of Wilson, the average monthly energy

intensity of all single family accounts is 0.72 kWh per square foot from January 2011 through December 2013.

Like the energy consumption groups, these accounts can be further broken down into monthly energy intensity

groups:

Zero Energy Intensity 0 kWh per square foot Low Energy Intensity 0.01 – 0.50 kWh per square foot Low-Mid Energy Intensity 0.51 – 1.00 kWh per square foot High-Mid Energy Intensity 1.01 – 1.50 kWh per square foot High Energy Intensity 1.51 – 2.00 kWh per square foot Super High Energy Intensity > 2.00 kWh per square foot

Table 11: Average Monthly Energy Intensity Breakdown Volume category based on premise account’s average energy intensity (kWh/sq.ft.) Energy Intensity Group Number of Accounts Total Usage (in kWh)

2011 2012 2013 2011 2012 2013

Zero (0) Low (0.01-0.50) Low-Mid (0.51-1.00) High-Mid (1.01-1.50) High (1.51-2.00) Super High (> 2.00)

65 4,165 11,511 3,978 787 189

71 5,007 11,590 3,330 578 117

60 5,036 11,478 3,341 685 132

. 33,094,540

172,086,038 74,879,795 16,976,263 4,144,211

. 40,678,340

166,855,051 60,709,705 12,094,585 2,766,768

. 40,930,079

165,308,994 62,205,942 14,561,061 3,034,441

TOTAL 22,225 22,201 22,289 322,035,372 302,135,165 305,915,736

Not surprisingly, just as the number of Wilson residential premise accounts that fall into higher average consumption groups declined between 2011 and 2012, the number of accounts in high energy intensity groups – specifically the super high group – experienced decline as well. Similarly, the number of High and Super High premise accounts increased again in 2013. The number of premise accounts that had average monthly energy intensity over 1.51 kWh/sq.ft was 817 accounts in 2013, or 3.8 percent of total accounts. Alternatively, in 2013 74 percent of total premise accounts had Low to Low-Mid energy intensity, or energy intensity that is less than the state average. This is an indication that the majority of houses in the City of Wilson are already quite efficiency on a per square footage basis. However, there is still a number of residential houses that are in need of energy efficiency improvements to bring their energy usage per square foot down to a more energy efficient target of 1.0 kWh/sq.ft.

6 Energy Information Administration, Office of Energy Consumption and Efficiency Statistics, Forms EIA-457 A and C-G of the 2009 Residential Energy Consumption Survey.



Figure 4: Number of Accounts for Each Energy Intensity Group for 2011, 2012 and 2013

H I G H T O S U P E R H I G H E N E R G Y I N T E N S I T Y A C C O U N T S

While all accounts using over 1,500 kWh of electricity each month are potential targets for energy efficiency

programs, of even greater concern are those houses that have high energy intensity (defined here as 1.50 kWh

per square foot or greater each month). Our analysis indicated that 721 premise accounts exceeded the 1.50

energy intensity threshold in each of the three analyzed years. These accounts have the following

characteristics:

246 (34 percent) of the accounts have forced air (ducted) heat and 203 of the records (28 percent)

indicate that the home has no air conditioning unit.

542 (75 percent) of the accounts have only one bill payer during the reporting period (25 percent have

changed ownership one or more times).

The average age of the house is 46 years, with 25 percent of the houses averaging 20 years.

75 percent of the houses have an appraised value below $60,863 (See Figure 5 below).

95 percent of the houses are less than 1,562 sq.ft. and 75 percent are 1,188 sq.ft. or less (See Figure 6

below).

Only 7 accounts participated in the Pete Street program.

H I G H S U M M E R / L O W W I N T E R E N E R G Y I N T E N S I T Y A C C O U N T S

In addition to the 721 premise accounts with high to super high energy intensity on an annual basis, 368 premise

accounts that use natural gas for heat have high or super high energy intensity during the summer months

(greater than 1.5 kWh per square foot each month). This would indicate that although these accounts might use

natural gas for heat, the homes would still benefit from energy efficiency improvements to improve energy use

during the summer.


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Figure 5: Distribution of High to Super High Energy Intensity Accounts by Appraised Value of House

Figure 6: Distribution of High to Super High Energy Intensity Accounts by Square Footage of House

Distribution of Appraised Value

Distribution of Property Square Footage



PETE STREET® PROGRAM

From September 2012 through August 2013, the City of Wilson utilized Clean Energy Durham’s Pete Street®

program to encourage residential customers to reduce energy use. Pete Street® is a neighborhood energy

efficiency program that involves training community volunteers to deliver neighbor-to-neighbor energy

efficiency workshops to customers of Wilson Energy. Prior to attending the workshops, Pete Street® participants

used, on average, 0.95 percent more electricity than customers not participating in the program. The average

energy intensity of the participants after the workshop is broken down into groups in Table 12. This analysis

compares the electricity usage of 228 workshop attendees to the general service population. As a group, the

Pete Street® accounts have a similar energy intensity distribution as the larger population, with approximately

3.5 percent falling into the high and super high energy intensity groups.

Table 12: Average Monthly Energy Intensity Breakdown for Accounts using Pete Street® Volume category based on premise account’s average energy intensity (kWh/sq.ft)

Energy Intensity Group Accounts w/Pete Street All Premise Accounts

Number Percent Number Percent

Zero (0) 0 0.00% 41 0.20% Low (0.01-0.50) 43 18.86% 4,526 21.53% Low-Mid (0.51-1.00) 133 58.33% 12,130 57.70% High-Mid (1.01-1.50) 44 19.30% 3,606 17.15% High (1.51-2.00) 7 3.07% 610 2.90% Super High (> 2.00) 1 0.44% 111 0.53%

TOTAL 228 100% 21,024 100%

D I F F E R E N C E - I N - C H A N G E A N A LY S I S To estimate the difference in monthly energy use by Pete Street® program workshop attendees after

participating in the program, a difference-in-change statistical approach was used. Since the workshops were

done over several months, it is difficult to compare all of them as a whole to the non Pete Street® participants.

However, an analysis was done on the changes for each individual premise account’s electricity usage and bill

before and after their participation in a workshop. Difference-in-change results are presented in Table 13 for

both average electricity consumption and average bill amount. This analysis indicates that Pete Street®

participants, on average, used 10 percent less electricity after particpating in the program – a monthly avoided

energy expenditure of roughly $18 per month.

Table 13: Difference-in-Change Analysis for Accounts using Pete Street (Pre- and Post-Program Analysis of Pete Street Participants)

PETE STREET® PARTICIPANTS

(n=228)

Average Monthly

Usage (kWh)

Average Monthly

Bill ($)

Before Pete Street® Workshop 1,170 $165.75

After Pete Street® Workshop 1,050 $147.62


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Target Groups for Energy Efficiency Program

Based on our analysis of high consumption and high energy intensity households, we are able to provide the City of Wilson with a list of premise accounts with particularly high energy use patterns indicative of potential problems. These premise accounts include the following sub-groups:

2,889 “super users” of electricity (over 2,000 kWh on average each month).

721 premise accounts with “high to super high” average energy intensity (over 1.5 kWh per month per

square foot).

309 accounts with overlap – both a “super user” of energy and “high-super high” energy intensity.

15 accounts with “high” or “super high” summer intensity and “low” winter intensity.

All of the premise accounts listed above include both owner-occupied and rental properties. Since the EFC’s file

did not contain the bill payer’s name, we were unable to match bill payer to property owner to determine

ownership. This analysis can be done with the approval of the City of Wilson.

Potential Next Steps

In addition to the target list of premise accounts provided above, this analysis of the City of Wilson’s residential electric and gas customer usage and expenditures revealed a few areas that might warrant additional analysis:

1. Property Turnover Analysis - Based on the number of bill payers associated with the premise accounts,

it appears that the City’s population has frequent turnover in their housing units. An analysis could be

done to determine if usage varies between bill payers or if the housing unit itself is the prime

determinant in electricity usage.

2. Renter Analysis – Based on census data, approximately 50 percent of the Wilson housing units are

rental properties. Our analysis of the City’s premise accounts does not differentiate between owner-

occupied and rental properties, however this analysis could be done by comparing property owner to

bill payer on each premise account.

3. Late Charge / Cut-Off Analysis – Although the billing file the EFC received did not include late charge or

cut-off information for each account, this type of information could be used to determine which premise

account in the target groups have the most immediate need for assistance through energy efficiency

improvements (and the resulting reductions in their energy bills).

4. Revenue Variability Analysis – Models could be developed to examine the variability of the Town’s

electric revenues to determine the impact of energy efficiency measures. In addition, the analysis could

include an evaluation of the percentage of revenue that is a result of base charges versus variable usage,

peak versus non-peak loads, and residential versus non-residential accounts.

Residential Electric and Gas Customer Usage and ......Using an identifier found on both the utility and the property data files (Parcel ID), we merged the utility billing file with

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