DOE/EIA-0555(96)/2

Energy 

Information ' 

Administratiori

Residential Lighting: 

Use and Potential Savin

September 1996
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DOE/EIA-0555(96)/2 

Distribution Category UC-950

Energy Consumption Series

Residential Lighting: Use and Potential Savings

September 1996

Energy Information Administration

Office of Energy Markets and End Use

U.S. Department of Energy

Washington, DC 20585

This report was prepared by the Energy Information Administration, the independent statistical and analytical 

agency within the Department of Energy. The information contained herein should not be construed as 

advocating or reflecting any policy position of the Department of Energy or any other organization.
Contacts

This publication was prepared by the Energy Information Administration (EIA) under the general direction of W. Calvin 

Kilgore, Director of the Office of Energy Markets and End Use (202-586-1617). The project was directed by Lynda T. 

Carlson, Director of the Office of Energy End Use and Integrated Statistics Division (EEUISD) (202-586-1112). 

Specific technical information may be obtained from the Residential Energy Consumption Survey (RECS) Manager, 

Robert Latta (202-586-1385). The FAX number for all EEUISD personnel is 202-586-0018.

Detailed technical questions on the topics indicated may be referred to the following members of the EEUISD:

Robert Latta End-Use Estimates, Sampling Design 202-586-1385

rlatta@eia.doe.gov

Michael Laurence RECS Questionnaires 202-586-2453

mlaurenc@eia.doe.gov

Vicki Moorhead Table Production 202-586-1133

vmoorhea@eia.doe.gov

Linda Owens Principal Author 202-586-5891

lowens@eia.doe.gov

Hattie Ramseur Related Statistical Publications 202-586-1124

hramseur@eia.doe.gov

Nanno Smith Public-Use Data, Computer Systems 202-586-5841

Design nsmith@eia.doe.gov

Acknowledgment

Dr. Wendel L. Thompson made a significant contribution to this report. Alas, Wendel retired on March 29, 

1996. During his career, his knowledge and unfailing effort were invaluable in making the RECS the highquality survey that it is. We will miss his expertise, dedication, good humor, and kindness. So long Mr. RECS; 

good luck in your retirement.

Data in these reports are in the public domain and, with appropriate credit, may be reproduced without permission. A 

suggested citation is "U.S. Department of Energy, Energy Information Administration, Residential Lighting: Use and 

Potential Savings" or "U.S. Department of Energy, Energy Information Administration, 1993 Residential Energy 

Consumption Survey."

Information is also available by accessing EIA's Home Page on the Internet at http://www.eia.doe.gov. Tables are also 

available on the CD-ROM. Public-Use Data Diskettes containing RECS data are available through the Office of 

Scientific and Technical Information and the National Technical Information Service. (See Appendix D, "Related EIA 

Publications on Energy Consumption," for ordering information.) For questions about the contents of EPUB reports and 

data and availability of this information on CD-ROM, call 202-586-8800.

Energy Information Administration / Energy Consumption Series 

Residential Lighting: Use and Potential Savings
Contents

Executive Summary ......................................................................... v

1. Introduction............................................................................. 1

The Residential Energy Consumption Survey .................................................... 1

Lighting Data from the RECS Household Questionnaire ........................................... 2

The RECS Lighting Supplement.............................................................. 2

2. Residential Lighting Profile ................................................................ 5

Types of Lights ........................................................................... 5

Location of Lights ......................................................................... 6

Lighting Usage and Costs ................................................................... 7

Estimating the Number of Indoor Lights ........................................................ 9

3. Potential for Savings ..................................................................... 11

Household-Level Savings .................................................................. 11

Aggregate-Level Savings .................................................................. 14

4. Detailed Tables ......................................................................... 15

Appendices

A. Survey Forms ........................................................................ 43

B. End-Use Estimation Methodology ........................................................ 53

C. Data Quality ......................................................................... 63

D. Related EIA Information on Energy Consumption ............................................ 65

Glossary .................................................................................. 71

Figures

1.1 Definition of Light ...................................................................... 1

2.1 Type of Light by Room .................................................................. 6

2.2 Regression Allocation Estimates of Electricity Consumption for Lighting, by Census Region, 1993 ....... 7

2.3 Electricity Consumption for Lighting, by Household Type ....................................... 7

2.4 Annual Electricity Expenditures for Residential Lighting, by Census Region, 1993 .................... 8

2.5 Electricity Consumption for Lighting, by Household Type ....................................... 8

3.1 Total Cost of Compact Fluorescent Bulb Compared to Incandescent Bulb (5 cents per kWh) ........... 12

3.2 Total Cost of Compact Fluorescent Bulb Compared to Incandescent Bulb (10 cents per kWh) .......... 13

3.3 Total Cost of Compact Fluorescent Bulb Compared to Incandescent Bulb (15 cents per kWh) .......... 13

4.1 Summary of Detailed Tables ............................................................. 15

4.2 Use of RSE Row and Column Factors ...................................................... 17

Tables

1.1 Comparison of Total RECS Sample and Lighting Supplement Subsample ........................... 3

1.2 Light Bulb Types in the RECS Lighting Supplement Questionnaire ................................ 3

2.1 Fluorescent Lights as a Percent of Total Lights ................................................ 5

2.2 Regression Allocation Estimates of Kilowatthours Used for Lighting by the Cost of Electricity, 1993 ..... 9

3.1 Assumptions Used in the Comparison Between Compact Fluorescent and Incandescent Lights ......... 11

3.2 Electricity Costs Versus Bulb Costs of Compact Fluorescent and Incandescent Light Bulbs,

 by Cost of Electricity ................................................................... 14

Energy Information Administration / Energy Consumption Series

Residential Lighting: Use and Potential Savings iii
4.1 Light Usage by Heated Floorspace Category, Millions U.S. Households, 1993 ...................... 18

4.2 Light Usage by Heated Floorspace Category, Percent of U.S. Households, 1993 ..................... 20

4.3 Light Usage by Total Number of Rooms, Million U. S. Households, 1993 ......................... 22

4.4 Light Usage by Total Number of Rooms, Percent of U.S. Households, 1993 ........................ 24

4.5 Light Usage by Family Income Category, Million U.S. Households, 1993 .......................... 26

4.6 Light Usage by Family Income Category, Percent of U.S. Households, 1993 ....................... 28

4.7 Light Usage by Household Size, Million U.S. Households, 1993 ................................. 30

4.8 Light Usage by Household Size, Percent of U.S. Households, 1993 ............................... 32

4.9 Mean Annual Electricity Consumption for Lighting, by Family Income by Number of Household

Members, 1993 ....................................................................... 34

4.10 Mean Annual Electricity Consumption for Lighting, by Family Income by Number of Rooms, 1993 ..... 34

4.11 Mean Annual Electricity Consumption for Lighting, by Number of Household Members by Number

of Rooms, 1993 ....................................................................... 35

4.12 Mean Annual Electricity Expenditures for Lighting, by Family Income by Number of Household

Members, 1993 ....................................................................... 35

4.13 Mean Annual Electricity Expenditures for Lighting, by Family Income by Number of Rooms, 1993 ..... 36

4.14 Mean Annual Electricity Expenditures for Lighting, by Number of Household Members by Number

of Rooms, 1993 ....................................................................... 36

4.15 Total Annual Electricity Expenditures for Lighting, by Family Income, Million U.S.

Households, 1993 ..................................................................... 37

4.16 Total Annual Electricity Expenditures for Lighting, by Number of Rooms, Million U.S.

Households,1993 ..................................................................... 37

4.17 Total Annual Electricity Expenditures for Lighting, by Number of Household Members, Million U.S.

Households,1993 ..................................................................... 38

4.18 Number of Lights by Room by Hours Used, 1993 ............................................ 39

4.19 Number of Lights by Type of Bulb by Hours Used, 1993 ....................................... 39

4.20 Number of Lights by Bulb Type by Room, 1993 ............................................. 40

4.21 Number of Households by Daily Kilowatthours by Number of Rooms ............................. 40

4.22 Number of Households by Daily Kilowatthours by Number of Household Members .................. 40

4.23 Number of Households by Daily Kilowatthours by Family Income ............................... 41

Al Lighting Information Collected by the Household Questionnaire and Lighting Supplement ............ 44

B1 Bulb Type and Wattage ................................................................. 54

Energy Information Administration / Energy Consumption Series 

iv Residential Lighting: Use and Potential Savings
Executive Summary

Potential Savings

The overwhelming majority of lights in residential households are incandescent-the least energy efficient of all light 

types (Figure ESI .). If households replaced the most intensively used bulbs with compact fluorescent bulbs, they would 

see a sizable savings in their electric bills. The total U.S. household energy that would be saved by replacing all 

incandescent bulbs used 4 or more hours per day would be 3 1 .7 billion kilowatthours (kWh) annually, or 35 percent of 

all electricity used for residential lighting.

Figure ES1

250

The amount of time it

takes for households to

see a simple payback

from compact fluores 

cent bulbs depends on

the price of electricity.

Assuming a 26-watt

compact fluorescent

bulb that costs 22

dollars, an average sized

75-watt incandescent

bulb that costs 75 cents,

and that the lights are

used 6.71 hours per day,

households see a savings

in 2.5 years, if the

electric rates are five

cents per kilowatthour

(Figure ES2).

Households see a

savings in 1.1 years if

the rate is 15 cents per

kilowatthour. At the

national level, the average cost of electricity is 8.4 cents per kilowatthour.2

for themselves in 1.7 years.

Total Number of Indoor Lights by Type and Hours Used

196.6

•MncandeEcoiv 

CDFluorescer

o 

o>

1 

2?

100 -

50

Hours Used per Day

Source: Energy Information Administration, 1993 Residential Energy Consumptk: r 

Housing Characteristics 1993, Table 3.22.

At this rate, compact fluorescent bulbs pay

The life-cycle cost of a light bulb includes the cost of the bulb itself, as well as the cost of the electricity required to 

power the bulb. Electricity costs are a large percent of the life-cycle cost of incandescent lights. Depending on the 

electric rates, electricity costs account for 78 to 91 percent of the life-cycle cost of incandescent lights, but only 37 to 

63 percent of the life-cycle cost of compact fluorescent bulbs (Figure ESS).

Compact fluorescent bulbs need about one-third of the power required by incandescent bulbs to emit the same amount 

of light.3 If one wanted to replace a 75-watt incandescent bulb, a 26-watt compact fluorescent would be an appropriate 

choice. Therefore, regardless of electricity costs, compact fluorescent bulbs offer a three-fold increase in efficiency.

'Among light bulbs used 4 or more hours per day, the average length of use is 6.7 hours.

2Table 5.4 of Energy Information Administration, Household Energy Consumption and Expenditures 1993, DOE/EIA-0321(93). (Washington, 

DC, October 1995), p. 46.

3 This is according to The Lighting Pattern Book for Homes, 1993, Lighting Research Center, Rensselaer Polytechnic Institute. 

There is some uncertainty about this point. The lighting industry states that compact fluorescent bulbs need only one-fourth the wattage of 

incandescent bulbs. EIA compared the savings of both 26-watt, 22-dollar compact fluorescent bulbs and 20-watt, 20-dollar compact fluorescent 

bulbs. There is very little difference in overall savings between these two types of bulbs. The biggest difference in savings is between the compact 

fluorescent and incandescent. Estimates of potential savings in this report are based on a 22-dollar, 26-watt compact fluorescent.

Energy Information Administration / Energy Consumption Series

Residential Lighting: Use and Potential Savings V
If compact fluorescent bulbs, by virtue of their high cost, do not produce large dollar savings to individual households, 

they still result in large savings of electricity and the fuels required to produce electricity.

Figure ES2. Number of Years Before Life-Cycle Cost of Incandescent

Bulb Exceeds Life-Cycle Cost of Compact Fluorescent Bulb 

(Simple Payback, Lights on 6.7 Hours per Day)

0.5

0.0

5 10 15

Cost of Electricity (Cents per kWh)

Source: Energy Information Administration, Office of Energy Markets and End Use.

Figure ESS. Electricity Cost as a Percent of Life-Cycle Cost of 

Incandescent and Compact Fluorescent Bulbs

At a usage rate of 6.7 hours per day, an 

average compact fluorescent bulb lasts 4.1 

years; an incandescent bulb lasts 3.5 

months.

The figure on the right shows the cost of 

electricity as a percent of the life-cycle cost 

of incandescent bulbs and compact 

fluorescent bulbs, calculated over a period 

of 4.1 years.

The life-cycle cost of a light bulb includes 

the cost of the bulb itself, as well as the cost 

of the electricity that powers the bulb. 

Electricity costs are a large percent of the 

life-cycle cost of incandescent bulbs. 

As the cost per kilowatthour increases, 

electricity costs account for a higher percent 

of the life-cycle cost of both bulbs.

100 n

w; Qr. O 80

O

O

0) Q.

60-

40

20-

I Incandescent DCompact Fluorescent f

78

Cost of Electricity (Cents per kWh)

Source: Energy Information Administration, Office of Energy Markets and End Use.

VI

Energy Information Administration / Energy Consumption Series 

Residential Lighting: Use and Potential Savings
Residential Lighting Profile

According to the 1993 Residential Energy Consumption Survey, U.S. households have, on average, 5.4 indoor lights that 

are on one or more hours per day, and 8.9 lights that are on 15 minutes or more per day.4 They use 940 kWh of 

electricity for lighting each year, and spend 83 dollars on electricity for lighting. Their expenditures on electricity for 

lighting are about 10 percent of their total electric bill.

Nearly every household uses lights and all households with lights use electricity to power them. However, electricity 

consumption for lighting is only 9.4 percent of all electricity consumption in the residential sector. Space heating, water 

heating, air conditioning and other appliances each accounts for more electricity use than lighting (Figure ES4).

Air Conditioning (13.9)

Space Heating (12.3)—, 

Water Heating (10.3)—

Refrigerators (13.9)'

The bedroom is the room Figure ES4.

that contains the most

household lights. !

However, the lights in the

living room and kitchen

are used the greatest

number of hours (Figure

ESS). Although 27

percent of all lights are in

bedrooms, they use only

19 percent of the total

light-hours.5 On the other

hand, the living room has

only 17 percent of all

lights, but accounts for 22

percent of all light-hours.

One reason bedrooms

have the highest number

of lights is that the

average home has 2.6 bedrooms.

The cost of electricity varies by Census 

region, from 7.7 cents per kilowatthour in 

the South to 11.4 cents per kilowatthour in 

the Northeast. The Midwest and West 

have similar rates-8.1 and 8.3 cents 

respectively. As the cost of electricity 

increases, households use less of it for 

lighting. However, with increasing 

electricity prices, the amount of electricity 

used for lighting accounts for a greater 

percentage of the total electric bill (Figures 

ES6 and ES7). This occurs because when 

electricity prices are higher, households 

choose fuels other than electricity for the 

more intensive uses, such as space heating, 

water heating, and cooking.

Total Electricity Consumption by End Use 

(Percent)

Lights (9.4) 

TVs (7.4)

Clothes Dryers :'£

Freezers (4.2) 

Ranges/Ovens (i

All Others (20.7)

Source: Energy Information Administration, 1993 Residential EnergyConsumption ' 

Household Energy Consumption and Expenditures 1993, Table 31

Figure ESS. Lights and Hours Used by Room 

(Percent)

Bedrooms

Kitchen

Living Room

Bathrooms

Family Room

Dining Room

Hallways

Other Rooms

I Source. Energy Information Adrrnnistiation 

!Survey.

0 15 20 

Percent of Total

Form E!A-457H ot the 1993 Residential E

4From these two estimates, one cannot conclude that 3.5 lights are used between 15 minutes and one hour per day because the estimates of 

lights used 15 minutes or more are from the Lighting Supplement Questionnaire, while the estimates of lights used one hour or more are from the 

RECS Household Questionnaire (see Chapter One for more details about these questionnaires).

'Light-hours are the total number of hours that all lights in the household are used. For example, if a household has 7 lights, and they are all 

used, on average, 2 hours a day, then there are 14 light-hours per day in that household.

Energy Information Administration / Energy Consumption Series 

Residential Lighting: Use and Potential Savings VII
Figure ES6. Regression Allocation Estimates of Electricity

Consumption for Lighting, by Cost of Electricity and 

__ Household Type ____________________

I""" 1,46cT-|

03 

=!

1,200

1,000 -

Household Type 

iSingle-Family Homes departments MMobile Homes

942

0 to 7.49 7.5 to 12.49 

Cents per kWh

12.5 or More

Q=Fewer than 10 cases were sampled.

Source: Energy Information Administration, Forms EIA-457A-C and E of the 1993 Residential 

;Energy Consumption Survey. __ ___ _ _ _ ____ _ _________

Figure ES7. Regression Allocation Estimates of Lighting as a

Percent of Total Electric Bill, by Cost of Electricity and 

_ Household Type___ _ _ __ ___ ___

;CQ 

o

o 

c

ICL

20

15 -

10 -

Household Type 

ISingle-Family Homes OApartments MMobile Homes

0 to 7.49 7.5 to 12.49 

Cents per kWh

12.5 or More

Q= Fewer than 10 cases were sampled.

Source: Energy Information Administration, Forms EIA-457A-C and E of the 1993 Residential 

Energy Consumption Survey.

VIII

Energy Information Administration / Energy Consumption Series 

Residential Lighting: Use and Potential Savings
Data Sources

The 1993 Residential Energy Consumption Survey collected information about lighting from two sources the Household 

Questionnaire, answered by 7,111 households, and a Lighting Supplement, administered to a subset of 474 households.

General descriptions of the basic types of lights discussed in this report are presented in Figure ESS.

Figure ESS. Common Residential Liqht Bulbs and Their Characteristics

Light Bulb Basics

Light-bulb electrical use is rated in watts; light ouput in lumens. In the same way 

that miles per gallon (MPG) allows you to compare the fuel efficiency of different 

cars, lumens per watt is the common denominator that allows you to compare the 

light output of different types of bulbs.

Here is a quick look at the most common household light bulbs.

Incandescent ________________.__

W

Produces 14 to 18 lumens per watt 

Lasts 750 to 1,000 + hours, depending on wattage 

Widest variety of sizes, shapes, and specialty bulbs 

Standard one-piece with screw base (Edison sockets) 

Produces different effects with variety of coatings 

Dimmable with standard equipment

Fluorescent Tube

Layar 1 

Circlra

Produces up to 105 lumens per watt

Lasts 6,000 to 20,000 hours

Variety of lengths and diameters

One-piece with twist-pin socket

Produces "warm" to "coo!" gradations of light

Not dimmable without special ballasts and wiring

Compact Fluorescent

Produces up to 105 lumens per watt

Lasts 10,000 hours

Limited shapes and some size mismatches with

fixtures

One-piece, or modular with replaceable bulb unit

Produces murkier light, but approaches standard

bulbs

Not dimmable without special ballasts and wiring

Produces 15 to 22 lumens per watt

Lasts 2,500 to 3,500 hours

Standard one-piece with screw base (Edison socket)

or special tube-like bulb

Produces clean light 25 percent brighter than

standard incandescent bulbs

Dimmable with standard equipment

Note: All figures are approximate because efficiency and durability are subject 

to a great number of variables-some in manufacturing and many in everyday 

installation and use.

Source: Energy Information Administration, Office of Energy Markets and End Use.

Energy Information Administration / Energy Consumption Series 

Residential Lighting: Use and Potential Savings IX

1. Introduction

The 1993 Residential Energy Consumption Survey (RECS) was the first to permit the estimation of annual kilowatthours 

(kWh) used for lighting. The survey contained more detailed questions about the number of indoor lights used for 

specific amounts of time and more detailed questions about the use of outdoor lights than did previous surveys. In 

addition to these basic questions on the Household Questionnaire, the 1993 RECS also included a supplementary 

questionnaire, administered to a subset of households, that contained more detailed information about the types of lights 

used in the household, the rooms in which they were located, and the amount of time they were used.

The Residential Energy Consumption Survey

The 1993 RECS is the ninth survey in a series of nationwide household energy consumption surveys conducted since 

1978 by the Energy Information Administration (EIA) of the U.S. Department of Energy. The survey consists of three 

parts:

 EIA interviews households for information about fuels used, how fuels are used, energy-using appliances, structure 

features, energy-efficiency measures taken, and demographic characteristics of the household. Most of the 

interviews are personal interviews that take place in the respondents' homes. In households where personal 

interviews are not completed, EIA attempts telephone interviews. In households where neither the personal 

interview nor the telephone interview is successful, a shortened version of the questionnaire is mailed to the 

household.

 EIA interviews the rental agents for those households whose rent includes some portion of their utility bills. This 

information is used to augment information from those households that may not be knowledgeable about the fuels 

used for space heating or water heating.

 After obtaining permission from respondents, EIA mails questionnaires to their energy suppliers to collect the actual 

billing data on energy consumption and expenditures.

In the 1993 survey, more than 7,000 households were surveyed, using complex sampling methods. These methods 

allowed EIA to collect information from a small number of the 97 million households in the nation, yet use that 

information to make inferences about the total population.6 The information collected represents the 97 million 

households nationwide. The data collected from the 1993 RECS are presented in two statistical reports: Housing 

Characteristics 1993 and Household Energy Consumption and Expenditures, 1993.

Figure 1.1. Definition of Light

For the purposes of both the RECS Household Questionnaire and the Lighting Supplement Questionnaire, EIA 

defines a light as every light bulb turned on by a single switch. If a light has only one switch, it is counted as one 

light, even if it has more than one bulb. A fixture or lamp with two switches controlling different bulbs is counted 

as two lights. If two switches control the same light (for example, switches at both ends of the hallway control a 

hall light), that is one light. In the Lighting Supplement Questionnaire, the wattage of lights containing more than 

one bulb is determined by adding the wattage of each bulb. Outdoor lights are counted on the RECS Household 

Questionnaire only if the light is controlled by the respondent.

'For further information about the RECS sample design, see Energy Information Administration, Appendix A of Housing Characteristics, 1993 

DOE/EIA-314 (93) (Washington, DC, June 1995) p. 207 or Energy Information Administration, Sample Design for the Residential Energy 

Consumption Survey, DOE/EIA-0555 (94)/l (Washington, DC, August 1994).

Energy Information Administration / Energy Consumption Series

Residential Lighting: Use and Potential Savings 1
Lighting Data from the RECS Household Questionnaire

The RECS Household Questionnaire (Form EIA-457A) asked only a few questions about lighting in the household (see 

Appendix A). The survey asked respondents to consider a typical November weekday and report how many indoor lights 

were on 1 to 4 hours a day, 4 to 12 hours a day, and more than 12 hours per day, and how many of those lights were 

fluorescent. Respondents were also asked to describe their outdoor light usage, by giving information about the types 

of outdoor lights, the length of time they were used, and the total wattage of all outdoor lights.

The RECS Lighting Supplement

The RECS Lighting Supplement (Form EIA-457H) was a short questionnaire completed by 474 of the 7,111 households 

that responded to the RECS Household questionnaire. The 474 households are a proportional sample of all households 

in the United States. The oversampling that occurred in the 1993 RECS was not retained in the Lighting Supplement, 

so all households selected in the Lighting Supplement have equal sampling weights and represent the same number of 

households nationwide. The data collected from the Lighting Supplement were checked for logic and consistency and 

were edited when necessary. However, there were no imputations for missing data. See Table 1.1 for a comparison of 

the RECS sample and the Lighting Supplement subsample.

The primary purpose of the Lighting Supplement was to collect data to develop a model to predict electricity 

consumption for lighting. The Supplement provides information on the number of lights used 15 minutes or more, the 

hours used, the room where each light is located, the type of light, and the approximate wattage of each light. Although 

the Supplement provides more detail than the main questionnaire, it is limited to indoor lights. See Appendix A for a 

copy of the Lighting Supplement.

The Detailed Tables in this report contain data from both the Household Questionnaire and the Lighting Supplement 

Questionnaire. The RECS sample was designed to represent the entire U.S. population of residential households. 

Consequently, tables that are compiled from the Household Questionnaire include weighted data. On the other hand, 

the main purpose behind the Lighting Supplement Questionnaire was to gather enough representative data to develop 

a household-level model of lighting consumption. Therefore, data from the Lighting Supplement are not weighted and 

represent only the households that participated in the Lighting Supplement. 7 However, as Table 1.1 shows, the 

households that participated in the Lighting Supplement have similar energy-related characteristics as those households 

that participated in the RECS Household Questionnaire.

For the sake of simplicity, the remainder of the report will refer to the RECS Household Questionnaire as the RECS 

Survey. The Lighting Supplement Questionnaire will be referred to as the Lighting Supplement.

Estimating Kilowatthours (kWh)

For each light used 15 minutes or more per day, the Lighting Supplement asked respondents what types of lights they 

had in each room in the house and the approximate wattage of each. The possible responses for bulb type and wattage 

are listed in Table 1.2.

The Supplement also asked respondents how long each light was used in a day.

Based on the bulb type and approximate wattage, a specific wattage was assigned to each light type. The bulb type and 

the hours of use were used to calculate an estimate of annual kWh for each household in the supplement. Appendix B 

gives the details of this calculation.

7See the notes at the end of each table for information about the source of the table.

Energy Information Administration / Energy Consumption Series 

2 Residential Lighting: Use and Potential Savings
Computation of End-Use Estimates

All of the RECS end-use estimates data are determined by a nonlinear regression that allocates some portion of the total 

consumption of each fuel to the specific end uses that consume that fuel. In previous surveys, end-use consumption for 

space heating, air conditioning, water heating, refrigeration, and appliances was calculated. Because of the data collected 

in the Lighting Supplement, it was possible to model lighting consumption of electricity by using the Supplement and 

then applying the model to the total sample to estimate the amount of electricity consumed by lighting in U.S. 

households. Appendix B contains a complete description of the end-use estimation methodology.

Table 1.1 Comparison of Total RECS Sample and Lighting Supplement 

Subsample

Household Characteristic

Percent of Households with 

Characteristic

Total Sample 

(11=7,111)

Lighting

Supplement

(n=474)

Census Region

Northeast ................................... 20.2 18.5

Midwest .................................... 24.1 24.9

South ...................................... 34.7 36.9

West ....................................... 21.1 19.6

Type of Home 

Single Family Detached ........................ 61.5 61.1

Single Family Attached ........................ 7.6 7.2

Apartment in Building with 2-4 Units .............. 8.3 7.8

Apartment in Building with 5 or More Units ......... 16.8 16.5

Mobile Home ................................ 5.8 7.4

Income

Less than $20,000 ........................ 36.6 38.4

$20,000to $49,999 ........................... 41.7 41.8

$50,000 to $74,999 ........................... 13.1 13.7

$75,000 or More.............................. 8.6 6.1

Average per Household 

Floorspace (square feet) .................... 1875.0 1855.0

Electricity Rate (dollars per 1,000 kWh) ......... 89.2 86.1

Number of Household Members .............. 2 - 6 2 -6

Number of Rooms ........................_________5 - 5__________6 - 1

Source: Energy Information Administration, Office of Energy Markets and End Use, Forms EIA-457A-C, 

E, and H of the Residential Energy Consumption Survey.

Table 1.2. Light Bulb Types in the RECS Lighting Supplement Questionnaire

Incandescent Fluorescent Halogen

Low (10 to 40 watts) 

Medium (41 to 149 watts) 

High (150 watts or more)

Short (less than 24 inches) 

Long (24 inches or more) 

Compact

One type only

Source: Energy Information Administration, Office of Energy Markets and End Use, Form EIA-457H of the 1993 Residential Energy 

Consumption Survey.

Energy Information Administration / Energy Consumption Series 

Residential Lighting: Use and Potential Savings

2. Residential Lighting Profile

This section contains a basic profile of lighting use in residential households. It includes brief discussions about the 

characteristics and location of lights used in residential households, as well as descriptions of the amount of electricity 

used for lighting and variations in households' consumption of electricity for lighting.

Types of Lights 

Dominance of Incandescent Lights

The majority of light bulbs in residential households are incandescent. According to the RECS Survey, 453 million lights 

out of a total of 523 million used one or more hours per day are incandescent (87 percent). 8 The Lighting Supplement 

also estimates that 87 percent of residential lights used 15 minutes or more per day are incandescent.

Fluorescent Lights of All Types

Thirteen percent, or 69.5 million lights used one or more hours per day are fluorescent. Fluorescent lights tend to be used 

more hours per day than incandescent lights. Twenty-one percent of the lights used more than 12 hours per day are 

fluorescent lights (see Table 2.1).9

Table 2.1 Fluorescent Lights as a Percent 

______of Total Lights__________

Hours Used per Day

1 to 4 11.7 

4 to 12 13.2 

More than 12______________20.5_____

Source: Energy Information Administration, Office 

of Energy Markets and End Use, Form EIA-457 A of 

the 1993 Residential Energy Consumption Survey.

Compact Fluorescent Lights

According to the RECS Survey, compact fluorescent lights are used in 8.9 percent of residential households, although 

49 percent of the homes reported knowing about them. 10 The percentage of households using compact fluorescent lights 

varies slightly by Census region, with households in the Northeast being somewhat more likely to use them, presumably 

due to higher electricity prices. The Lighting Supplement data show that less than one percent of all lights used 15 

minutes or more per day are compact fluorescent.

Halogen Lights

A halogen light is a type of incandescent light that is slightly more efficient than the common incandescent light. A 100- 

watt common incandescent produces 17.5 lumens per watt compared with a 100-watt halogen, which produces 18.8 

lumens per watt. These differences are much smaller than the comparison with the compact fluorescent, but the typical 

cost of a halogen light is 4 dollars versus 20-22 dollars for a compact fluorescent. Halogen lights are more widely known

"Derived from Table 3.22, Energy Information Administration, Housing Characteristics 1993, p. 128.

"Ibid.

'"See Figure 2.1 of Energy Information Administration, Housing Characteristics 1993, p. 7.

Energy Information Administration / Energy Consumption Series

Residential Lighting: Use and Potential Savings 5
than the compact fluorescent (66 percent of households have heard of them), but they are used in only ! 2 percent of 

homes. Again, the RECS Survey shows this varies by Census Region, with households in the Northeast and West being 

somewhat more likely to use halogen lights.

Location of Lights

Rooms

Incandescent lights predominate in all rooms in the household, both in number and in hours used (Figure 2.1). In all

rooms, except for the kitchen and "other" (which includes laundry rooms), incandescent lights account for at least 90

percent of the hours used. Although

the kitchen and "other rooms" contain

the most fluorescent lights, fluorescent

lights in these rooms still account for

only 30 to 33 percent of the hours

used.

Figure 2.1. Type of Light by Room

Incandescent nFluorescent BOther/Unknowni

Bedrooms

Rooms that contain the most lights do 

not necessarily consume the most 

electricity for lighting. For example, 

bedrooms have the most lights, 

followed by the kitchen and the living 

room. However, the lights in the 

kitchen are used the most hours, 

followed by the living room and 

bedrooms (Figure ESS).

Kitchen

Living Room

Bathrooms

Family Room

Dining Room

Hallways

Other Rooms

20 40 60 80

Percent of Total Light Hours

100

hOr lights USed at least ID minutes per : source: Energy Information Administration, Form EIA-457H ol the 1993 Residential Energy Consumption

day, the average use per light in Survey

kitchens is about 3.8 hours, followed

by living rooms (3.4 hours per light), and family rooms (3.3 hours per light). Rooms where lights are used less

intensively are bedrooms (1.6 hours per light) and bathrooms (1.8 hours per light).

Outdoor Lights

About two-thirds of U.S. homes use outdoor lighting. The percentage is much lower for apartments in buildings 

containing 5 or more units. In these structures, only 28 percent of the households reported using an outdoor light." The 

percentage using outdoor lights in other types of structures is 76 percent for single-family homes, 69 percent for mobile 

homes, and 59 percent for small apartment buildings (2 to 4 units).

In approximately half of the households that use outdoor lights, the wattage of all outdoor lights combined for each 

household is below 150 watts. We may assume it is over 150 watts for the other half. 12 Lights are turned on for the 

evening in 41 percent of the homes, while other homes using outdoor lights leave them turned on all night or have them 

controlled in some way. Only three percent of homes use a high-intensity discharge light outdoors (see the Glossary for 

definitions of different types of lights).

"This percentage refers only to outdoor lights controlled by the household, not those maintained by the property managers. 

' 2Of all the households that use outdoor lights, less than 1 percent did not answer the question about total wattage.

Energy Information Administration / Energy Consumption Series 

Residential Lighting: Use and Potential Savings
Lighting Usage and Costs

Usage

In 1993, the average household consumed 940.5 kWh of electricity for lighting. Electricity consumption for lighting 

increases with increasing income, number of household members, and number of rooms in the housing unit (see Tables 

4.9,4.10, and 4.11 of the Detailed Tables). Consumption also varies with Census region. Households in the South and 

Midwest consume the most electricity for lighting (Figure 2.2). Perhaps this is because electricity costs less in those 

Census regions.

An alternative way of displaying 

electricity consumption for lighting is 

to show the percent of households in 

consumption categories. For 

example, Figure 2.3 shows a 

distribution of households, for each 

household type, by the amount of 

electricity for lighting, in 250 kWh 

increments. The largest number of 

apartments (32.9 percent) consume 

between 250 and 499 kWh. The 

largest number of mobile homes (24.0 

percent) consume between 500 and 

749 kWh. Among single-family 

homes, the consumption is higher, 

with 17.4 percent using between 750 

and 999 kWh.

Figure 2.2. Regression Allocation Estimates of Electricity

Consumption for Lighting, by Census Region, 1993

LJJ

Northeast Midwest South West

Census Region

Source: Energy Information Administration, Forms EIA-457A-C and E of the 1993 Residential 

Energy Consumption Survey.

Figure 2.3. Electricity Consumption for Lighting, by 

Household Type

-»AII Homes 

+Single-Family Detached

-*-Mobile Homes

-•Apartments i

Annual kWh for Lighting

Source: Energy Information Administration, Forms EIA-457A-C, and E of the 1993 Residential Energy 

[Consumption Survey-__________________ ___________________________

Costs

The RECS survey shows that the average 

annual cost of electricity for lighting is 

approximately 83 dollars per household (1993 

dollars), which is about 10 percent of the 

average expenditures on electricity in 1993 

($840). The 25th and 75th percentiles show 

that 25 percent of the households paid less than 

43 dollars and 25 percent paid more than 109 

dollars. One-half paid between 43 dollars and 

109 dollars. Although households in the South 

and Midwest consumed more electricity for 

lighting, households in the Northeast paid the 

most for electricity for lighting because they 

had the highest average electricity prices 

(Figure 2.4).

Variation in Lighting Consumption Among Households

The annual electricity consumption for lighting in 1993 was 940 kWh per household-9 percent of the total consumption. 

This figure includes both indoor and outdoor lights. Figure 2.5 shows the cumulative percent of households by annual

Energy Information Administration / Energy Consumption Series 

Residential Lighting: Use and Potential Savings
electricity consumption for lighting. The median consumption for all households is 818 kWh. Households in singlefamily homes use the most electricity for lighting, while households in apartment buildings use the least (median of 953 

and 484 kWh, respectively).

Figure 2.4. Annual Electricity Expenditures for Residential 

_____Lighting, by Census Region, 1993_______

120 -i

100 -

20 -

Just as total energy use varies considerably 

from one household to another, so does the 

percentage of electricity used for lighting. 

This percentage varies because of the 

different uses that are made of electricity. 

Some households use electricity for some 

heavy work-heating the home, water heat 

ing, and air-conditioning, so their bills will 

be large and the lighting component a small 

part of the bill. Other households not using 

electricity for these heavy loads will show 

a higher percentage of their electricity used 

for lighting.

The variation hi the percentage of electric 

ity used for lighting depends on the cost of 

electricity, what it is used for, and the 

climate where the household is located. 

Unlike space heating and water heating,

where nonelectric energy sources are chosen when the cost of electricity gets too high, alternative sources for lighting 

are not much used today. Consequently, in areas where the cost of electricity is high, one sees a small decrease in the 

amount of electricity used for lighting (Table 2.2), although these smaller amounts represent a larger share of the total 

electricity bill.

Figure 2.5. Electricity Consumption for Lighting, by Household Type_______

Northeast Midwest

Census Region

Source: Energy Information Administration, Forms EIA-457A-C, and E of the 1993 Residential 

Energy Consumption Survey.___________________________________ ___

3,500

3,000

All Homes -f-Single-Family -e- Mobile Homes * Apartments |

10 25 50 75 90

Cumulative Percent of Households

99

Source: Energy Information Administration, Forms EIA-457A-C, and E of the 1993 Residential Energy 

Consumption Survey._______________ ________________________________

Energy Information Administration / Energy Consumption Series 

Residential Lighting: Use and Potential Savings
Table 2.2 Regression Allocation Estimates of Kilowatthours Used for Lighting by 

the Cost of Electricity, 1993

Cost of Electricity 

(cents per kWh)

0 to 7.49 ........................

7.5 to 12.49 .....................

12.5 or More .....................

Annual kWh for Lighting

Single-Family Home

1,134 

1,051 

942

Apartment

636 

584 

512

Mobile Home

875 

869 

Q

Q=Data withheld because fewer than 10 households were sampled.

Source: Energy Information Administration, Office of Energy Markets and End Use, Forms EIA-457A, B, E, and H of the 1993 

Residential Energy Consumption Survey and EIA-861 of the 1993 Annual Electric Utility Report.

Lighting Consumption Compared to Other End Uses

Lighting accounted for 9.4 percent of all electricity consumption in U.S. households in 1993, less than air conditioning, 

water heating, space heating, or refrigeration (Figure ES4). 13 Residential lighting thus represents three percent of total 

U.S. sales of electricity to all sectors.'4 Because the end-use estimates do not distinguish between indoor and outdoor 

lighting, this estimate of lighting consumption includes both.

Virtually 100 percent of households use electricity for lighting, while less than 70 percent use it for air conditioning and 

less than 40 percent use it for space heating and water heating. However, because space conditioning and water heating 

are more intensive users of electricity than lighting, they account for a greater amount of the total electricity consumption 

in the residential sector. In 1993, air conditioning consumed 13.9 percent, water heating 10.2 percent and space heating 

12.3 percent. Lighting consumed 9.4 percent.

Estimating the Number of Indoor Lights

The number of indoor lights used 1 hour or more per day can be predicted with some accuracy from knowing one fact 

about people (the number of persons in the household) and one fact about the housing structure (the number of rooms). 

The number of indoor lights can be predicted from the following equation:

Number of Indoor Lights = 0.6 + 0.4*(number of household members) + 0.7*(number of rooms)

For this calculation, rooms are defined as kitchens, dining rooms, living rooms, family rooms, and bedrooms. Rooms 

do not include bathrooms, basements, or utility rooms. For example, one person living in a four-room housing unit would 

be expected to use about four lights for one hour or more per day. Other factors, such as the age of the occupants, would 

be expected to affect this estimate for any particular household.

"For a more complete list of end-use consumption for electricity, see Table 3.1 in Energy Information Administration, Household Energy 

Consumption and Expenditures 1993, p. 10.

14Thisis91 billion kWh out of a total sales of 2,861 billion kWh. For total kWh sales of electricity for 1993, see Table 1, Electric Sales and 

Revenue 1993, DOE/EIA-0540(93). (Washington, DC, January 1995), p. 5.

Energy Information Administration / Energy Consumption Series 

Residential Lighting: Use and Potential Savings

3. Potential for Savings

Household-Level Savings

Households in the U. S. contain a total of 523 million lights that are on 1 or more hours a day 282 million of these are 

on 4 or more hours a day. The majority of these lights are incandescent-88 percent of those on 1 to 4 hours and 85 

percent of those on 4 or more hours. Given the greater efficiency of compact fluorescent lights, how much would 

households save if they replaced their incandescent lights with compact fluorescents? Replacing incandescent lights that 

are on for a short period of time with compact fluorescents is not very cost effective, because compact fluorescents cost 

so much more than incandescents (about 22 dollars compared to 75 cents). However, at longer periods of use, compact 

fluorescents do become cost effective, in spite of their high initial cost. Figures 3.1 through 3.3 compare the total cost 

of an incandescent light with a compact fluorescent light, using the assumptions listed in Table 3.1.

Table 3.1 Assumptions Used in the Comparison Between Compact Fluorescent 

and Incandescent Lights

Initial Cost of Bulb .... 

Wattage

Life of Bulb (hours) ... 

Hours Used per Day . . .

Incandescent

75 cents 

75 watts

750 hours 

6.7 hours

Compact Fluorescent

22 dollars 

26 watts

1 0,000 hours 

6.7 hours

Sources: Energy Information Administration, Office of Energy Markets and End Use; Lighting Research 

Center, Rensselaer Polytechnic Institute, The Lighting Pattern Book for Homes, 1993.

Assumptions Used in the Calculation of Potential Savings 

Cost and Life of Bulb

A 75-watt incandescent bulb costs about 75 cents and has a rated life of 750 hours. A 26-watt compact fluorescent bulb 

costs about 22 dollars and has a rated life of 10,000 hours. The calculations in this report assume there are no additional 

costs involved in the replacement of incandescent lights, such as bulb breakage or the purchase of new fixtures. They 

also assume the bulbs last their rated number of hours, although the actual life of light bulbs varies from bulb to bulb.

Light Output

Light output is measured in lumens. A 75-watt incandescent bulb emits approximately 1,190 to 1,220 lumens while a 

26-watt compact fluorescent bulb emits about 1,550 lumens. Although an 18-watt compact fluorescent has the same light 

output rating as a 75-watt incandescent (1,100 to 1,250 lumens), a bulb's rated light output is not the only consideration 

in choosing a replacement bulb. The location and position of the fixture affect the actual output of compact fluorescent 

bulbs, and the quality of the light may differ between compact fluorescents and incandescents. Consequently, for 

satisfactory light output, a compact fluorescent bulb may need a higher rated light output than the incandescent it is 

replacing. For these reasons, a 26-watt compact fluorescent bulb is used in the calculations, rather than an 18 watt bulb.

Hours of Use

Repeatedly switching a compact fluorescent light on and off reduces the life of the bulb. Therefore, compact fluorescent 

lights provide the biggest savings when they are used to replace incandescent lights that are used several hours per day. 

The calculations in this report are based on lights that are used four or more hours per day. According to the Lighting 

Supplement data, these lights are on an average of 6.7 hours per day.

Energy Information Administration / Energy Consumption Series

Residential Lighting: Use and Potential Savings 11
Simple Payback

The calculations are based on 1993 dollars. They do not take into account changes in energy costs or changes in the 

value of the dollar over the lifespan of a compact fluorescent bulb.

Universal Replacement

This report assumes that all incandescent lights used four or more hours per day can easily be replaced by compact 

fluorescent lights. This assumption ignores the fact that some compact fluorescent bulbs may not fit into fixtures 

designed for incandescent bulbs. The EIA does not have data on the percent of fixtures that could be successfully 

converted to compact fluorescent lights, so it is unclear how erroneous this assumption is.

Calculation of Savings

At a rate of use of 6.7 hours per day, a compact fluorescent bulb lasts, on average, about 4.1 years. By contrast, an 

incandescent bulb lasts about 3.5 months. Figures 3.1 through 3.3 show the savings that accrue over the expected life 

span of a compact fluorescent bulb. The figures include the cost of repeatedly replacing the incandescent bulb. The cost 

comparisons are calculated for three different electric rates-5, 10, and 15 cents per kWh.

When electricity costs 5 cents per kWh, compact fluorescent bulbs save money after about 2.5 years and result in a total 

savings of approximately 12 dollars by the end of the life span of the compact fluorescent bulb (Figure 3.1). At a cost 

of 10 cents per kWh, compact fluorescents save money after 1.5 years and result in a total savings of 36 dollars (Figure 

3.2). With the highest priced electricity--15 cents per kWh, compact fluorescents save money after only 1.1 years and 

result in a total savings of 60 dollars per bulb (Figure 3.3). The average household has only 2.5 incandescent lights that 

are on 4 hours or more, so assuming the same amount of savings per light, their total savings due to replacement would 

be twice the savings listed above. Therefore, even at the most expensive electric rates, an average household would save 

only about 120 dollars over a period of 4 years. For many households, this may not be incentive enough for them to 

purchase compact fluorescent bulbs.

Figure 3.1.

o

O

S 

o

140 -i

0

Total Cost of Compact Fluorescent Bulb 

Compared to Incandescent Bulb 

(5 cents per kWh)

Although these comparisons do not show a 

tremendous dollar savings in using com 

pact fluorescent lights, they do show a 

sizable savings in electricity. In each of 

these three figures, the line plotting the cost 

of the incandescent bulb has a steeper slope 

than the line plotting the cost of the com 

pact fluorescent, especially at higher elec 

tric rates. What this shows is that with 

incandescent bulbs, the life-cycle cost is 

composed largely of electricity costs. On 

the other hand, the life-cycle cost of com 

pact fluorescent bulbs is made up mostly of 

the cost of the bulb itself.

0.6 1.2 1.8 2.5 3.1 3.7

A

For example, over a period of 4.1 years, at 

5 cents per kWh, the price of electricity 

accounts for 37 percent of the life-cycle 

cost of a compact fluorescent light, but for

78 percent of the life-cycle cost of an incandescent light. Table 3.2 shows the cost of electricity and the cost of bulbs 

for fluorescent and incandescent lights, over a period of 4.1 years, by the price of electricity. The cost of powering a 

compact fluorescent bulb at the highest electric rate is little more than the cost of powering an incandescent at the lowest 

electric rate.

0.3 0.9 1.5 2.1 2.8 3.4

Years of Use (6.7 hours per day)

Source: Energy Information Administration, Office of Energy Markets and End Use.

12

Energy Information Administration / Energy Consumption Series 

Residential Lighting: Use and Potential Savings
Another advantage of compact fluorescent bulbs is convenience. Incandescent bulbs need to be replaced about 13 times 

more frequently than compact fluorescent bulbs. In areas such as hallways, where bulbs are hard to reach, and light 

quality is not of utmost importance, the convenience of compact fluorescent bulbs is a particular advantage.

Figure 3.2. Total Cost of Compact Fluorescent Bulb Compared to 

Incandescent Bulb 

(10 cents per kWh)

140 T """ ' _____________________ 

[^Incandescent -^-Compact Fluorescent I

o 

O"5 

"o

Years of Use (6.7 hours per day)

Source: Energy Information Administration, Office of Energy Markets and End Use.

Figure 3.3. Total Cost of Compact Fluorescent Bulb Compared to 

Incandescent Bulb 

(15 cents per kWh)

140 -,

£2 _cc "o

05 

O 

O

-^Incandescent -^Compact Fluorescent

2.5 3.1 3.7 

2.1 2.8 3.4 4

Years of Use (6.7 hours per day)

Source: Energy Information Administration, Office of Energy Markets and End Use.

Energy Information Administration / Energy Consumption Series 

Residential Lighting: Use and Potential Savings 13
Table 3.2 Electricity Costs Versus Bulb Costs of Compact Fluorescent and Incandescent Light Bulbs, 

by Cost of Electricity

Cost of Electricity (cents per kWh)

5 ..............................

10 ..............................

15 ..............................

Compact Fluorescent

Bulb Cost 

(dollars)

22 

22 

22

Electricity Cost 

(dollars)

Incandescent

Bulb Cost 

(dollars)

12.68 10.5" 

25.35 10.5 

38.03 10.5

Electricity Cost 

(dollars)

36.56 

73.13 

109.69

• Over a period of 4.1 years, a 75-watt incandescent bulb would have to be replaced 13 times. The initial cost of the first bulb, plus 13 

replacement bulbs, times the cost of each bulb equals $10.5 (i.e., 14 bulbs at 75 cents each). 

Source: Energy Information Administration, Office of Energy Markets and End Use.

Aggregate-Level Savings

Potential aggregate U.S. household energy savings for replacement of all incandescent bulbs used more than 4 hours per 

day amounts to 31.7 billion kWh annually. 15 This assumes that the average incandescent bulb is 75 watts and is replaced 

by a 26-watt compact fluorescent bulb. Thirty-eight percent of this savings, or 12 billion kWh, would come from 

replacing the 44.1 million bulbs used 12 or more hours per day and 62 percent, or 19.7 billion kWh, would come from 

replacing the 196.6 million lights used 4 to 12 hours per day. These potential energy savings are 35 percent of the 

electricity used for lighting in 1993 (91 billion kWh).

Two programs designed to encourage households to use compact fluorescent lights found that most of the participating 

households would not be willing to pay more than 10 dollars for a compact fluorescent bulb. 16 Given compact 

fluorescent bulbs cost 20 dollars or more, individual households may need some incentive to use them and to contribute 

to the aggregate savings in electricity.

"Because electricity generation requires the use of other fuels as input, the energy required to generate this 31.7 billion kWh is about 326 

trillion Btu (see Table A8 of Energy Information Administration, Monthly Energy Review, DOE/EIA-0035(96/08). (Washington, DC, August 

1996), p. 143.

"Leona Michelson and Brian Lonergan, "Bright Ideas in Residential Lighting," Proceedings from the ACEEE Summer Study on Energy. 

Efficiency in Buildings, 1992

14

Energy Information Administration / Energy Consumption Series 

Residential Lighting: Use and Potential Savings
4. Detailed Tables

These detailed tables are of three types. The tables displaying the number of households by hours of lighting use and 

household characteristics (Tables 4.1 through 4.8) were compiled from data collected on the RECS Household 

Questionnaire. The data in Tables 4.9 through 4.17 are based on information collected from the RECS Household 

Questionnaire and estimates derived from models developed with the Lighting Supplement data. Tables 4.18 through 

4.23 contain data collected directly from the Lighting Supplement. Figure 4.1 provides a summary of the three types 

of detailed tables.

Figure 4.1 Summary of Detailed Tables

Table 

Numbers Source of Table Source of Cell Estimates

Number of 

Households

Estimates of Standard 

Error

4.1-4.8 1993 RECS Household Weighted Survey Data 

Survey

4.9-4.17 1993 RECS Household Regression Estimates 

Survsy and Lighting 

Supplemeni 

Questionnaire

7,111 Presented in row ana column 

factors

7,111 Standard errors of data presented 

in row and column factors. 

Regression model errors no! 

included.

4.18-4.23 1993 RECS Lighting

Supplement

Questionnaire

Unweighted Survey Data 474 No estimates of standard errors.

The sample selected for the RECS Household Questionnaire was designed to provide population estimates by applying 

weights to the household data. In contrast, the Lighting Supplement sample was designed only to collect data upon which 

to base a model of lighting consumption, not to provide population estimates. Consequently, Tables 4.18 through 4.23 

do not contain estimates of standard errors. Tables 4.1 through 4.17 contain relative standard errors (RSE's) in terms 

of row and column factors.

Statistical Significance of Data 

Row and Column Factors

Tables 4.1 through 4.17 provide row factors in the far-right column and column factors on the top line of each table. 

These factors are to be used to determine the Relative Standard Error (RSE) for each estimate, which, in turn, can be used 

to determine the standard error and the confidence level of the estimate and to determine whether the difference between 

any two figures is statistically significant. However, since the RSE's are only approximate, standard errors, confidence 

intervals, and statistical tests must also be regarded as only approximate.

To calculate the RSE for a specific estimate, multiply the row factor by the column factor, as illustrated in Figure 4.2, 

an excerpt from Table 4.3 of this report. This table shows that there are 14.9 million households in the United States 

that have three to five rooms and have two lights on one to four hours a day. Multiplying the row factor (6.3) by the 

column factor (0.7) yields a relative standard error of 4.41 percent.

Standard Errors

Because the estimates presented in the following tables are based on a sample of residential housing units, they are 

subject to sampling error, or standard error. To determine the standard error for an estimate in these tables, multiply the 

approximate RSE by the estimate. For example, to determine the standard error of the estimate of the number of

Energy Information Administration / Energy Consumption Series 

Residential Lighting: Use and Potential Savings 15
households with three to five rooms that have two lights on one to four hours per day, multiply .0441 by 14.9 million. 

The result, .66 million households, is the approximate standard error for the estimate.

Confidence Levels

For each of the estimates given in Tables 4.1 through 4.17, a 95-percent confidence range can be determined with the 

estimate at the mid-point. To calculate the 95-percent confidence range for a given figure:

1. Multiply the RSE row factor by the RSE column factor to determine the approximate RSE.

2. Multiply the approximate RSE (divided by 100) by the estimate given in the table to determine the approximate 

standard error.

3. Multiply the result by 1.96 to determine approximate 2 standard errors.

4. Subtract the result of Step 3 from the given estimate to determine the bottom of the range.

5. Add the result of Step 3 to the given estimate to determine the top of the range.

The result of these steps will yield a range with the property whereby, in repeated surveys, the estimate would fall in the 

range constructed in this way 95 percent of the time.

For example, to determine the confidence range for the estimate highlighted in Figure 4.2:

1. Multiply 6.3 (the RSE row factor) by 0.7 (the RSE column factor), which yields 4.41 percent (the approximate 

RSE).

2. Multiply .0441 (the approximate RSE) by 14.9 million households (the estimate), which yields 0.657 million 

households (the approximate standard error).

3. Multiply 0.657 million households by 1.96, which yields 1.29 million households (approximate 2 standard 

errors).

4. To determine the bottom of the range, subtract 1.29 million households from 14.9 million, which yields 13.61 

million households.

5. To determine the top of the range, add 1.29 million households to 14.9 million, which yields 16.19 million 

households.

It can then be said with 95-percent confidence that, in 1993, the number of households with three to five rooms, that used 

two lights for one to four hours each day falls between 13.61 and 16.19 million households.

Statistical Significance Between Two Statistics

The difference between any two estimates given in the detailed tables may or may not be statistically significant. 

Statistical significance for the difference between two independent variables is computed as:

where S is the standard error, x, is the first estimate, and x2 is the second estimate. The result of this computation is to 

be multiplied by 1.96, and if this result is less than the difference between the two estimates, the difference is statistically 

significant.

Energy Information Administration / Energy Consumption Series 

16 Residential Lighting: Use and Potential Savings
Figure 4.2 Use of RSE Row and Column Factors

Table 4.3. Light Usage by Total Number of Rooms. 

Million U.S. Households, 1993

Housing Unit and Household 

Characteristics

RSE Column Factors

Total ............................

Indoor Electric Lights 

Total Number of Lights on 

1 to 4 Hours

None ....................... 

1 ...........................

2

q

4 ...........................

Total

0.4

96.6

') h

27.4

16 S 

9.2 

1 1.5

Souree. Knerf:\ Ir,lorm.i inn AdmmiMratuHi. O!l:ee o! Hner|iy Mark

Total Number of Rooms j 

(Excluding Bathrooms) |

1 or 2

2.9

3 to 5

0.7

6 to 8

0.7

3.2 474 402

5 5.0 3 S 

1. 2 I? I 72

9 or More

1.7

s S 

( .

 |-

.4 14.9 10.4 1. 2

t" ~ i~

.4 7.S 7.5

Q 32 51 

Q 34 6.2

ets and Knd Use. 19Q3 Residenlial F.ne

I I

1. 7

RSE 

Row 

Factors

i ' 

f>.f.

6 :

10 I

FL;V Cnns'imjition Survev

For example, from Figure 4.2, you can see that 13.1 million households have three to five rooms and use one light one 

to four hours per day. The number of households with six to eight rooms that use one light one to four hours per day is 

7.2 million. The difference between the two estimates is 5.9 million households. The standard error for the 13.1 million 

households (x,) is 0.62 million. The standard error for the 7.2 million (x2) households is 0.34 million:

0.342

S^ = 0.707

Multiplying 0.707 by 1.96 yields 1.39 million households. Since 1.39 million households is less than the 5.9 million 

difference between the two estimates, the difference is statistically significant.

Energy Information Administration / Energy Consumption Series 

Residential Lighting: Use and Potential Savings 17
Table 4.1. Light Usage by Heated Floorspace Category, 

Million U.S. Households, 1993

Homing Unit and Household 

Characteristic*

RSE Column Factor:

Total

0.4

Fewer

than

600

1.7

Heated Floorspace Category 

(square feet)

600 

to 

999

0.9

1,000

to 

1,599

0.8

1,600

to 

1,999

1.1

2,000

to 

2,399

1.2

2,400

to 

2,999

1.2

3,000

or 

More

1.2

RSE

ROW

Factors

Total................................................. 96.6 7.5 21.8 27.8 12.4 9.6 8.2 9.3 3.62

Indoor Electric Light* 

Total Number Ughts

1 to 4 Hours

Nona........................................... 9.6 1.2 2.2 2.7 1.1 0.9 0.7 0.6 11.83

1 ................................................. 22.1 2.4 6.7 6.5 2.5 1.5 1.5 1.1 7.39

2 ................................................. 27.4 2.4 6.9 8.0 3.6 2.4 2.1 2.0 6.60

3 ................................................. 16.8 0.8 3.4 5.2 2.2 2.0 1.5 1.8 8.57

4 ................................................. 9.2 0.4 1.4 2.5 1.4 1.1 1.0 1.3 11.13

5 or More.................................... 11.5 0.3 1.2 2.8 1.6 1.7 1.4 2.5 11.10

4 to 12 Hours

None........................................... 13.4 2.0 4.2 3.9 1.1 0.9 0.6 0.7 10.20

1 ................................................. 20.8 2.4 6.3 6.3 2.3 1.4 1.1 0.9 7.55

2 ................................................. 26.4 1.8 6.3 7.8 3.6 2.5 2.3 2.2 6.51

3 ................................................. 16.7 0.8 2.9 5.1 2.6 2.0 1.7 1.7 7.64

4 ................................................. 9.2 0.4 1.1 2.8 1.4 1.2 1.1 1.3 10.46

5 or More .................................... 10.0 Q 0.9 2.0 1.4 1.7 1.4 2.5 10.40

More than 12 Hours per Day

None........................................... 66.4 6.0 15.4 18.7 8.2 6.5 5.2 6.3 4.15

1 ................................................. 16.6 1.1 4.2 5.4 2.1 1.4 1.3 1.2 8.90

2 ................................................. 7.6 0.3 1.5 2.1 1.2 0.9 0.9 0.7 12.32

3 ................................................. 3.3 Q 0.5 0.9 0.6 0.5 0.3 0.5 17.49

4 ................................................. 1.5 Q 0.2 0.4 0.2 0.2 0.3 0.3 26.11

5 or More.................................... 1.2 Q Q 0.3 0.1 0.2 0.2 0.2 28.67

Incandescent Lights Used

1 to 4 Hours per Day

None........................................... 14.8 1.6 3.5 4.1 1.8 1.4 1.3 1.0 9.69

1 ................................................. 24.4 2.6 6.9 7.3 2.8 1.7 1.7 1.5 7.02

2 ................................................. 25.3 2.1 6.2 7.6 3.3 2.4 1.8 2.1 6.38

3 ................................................. 15.3 0.7 3.0 4.6 2.1 1.8 1.5 1.7 8.77

4 ................................................. 7.5 0.3 1.1 2.1 1.2 1.0 0.9 0.9 12.40

5 or More .................................... 9.4 0.3 1.0 2.1 1.2 1.4 1.1 2.2 12.28

4 to 12 Hours per Day

None........................................... 17.4 2.3 5.1 5.0 1.8 1.1 1.0 1.1 8.68

1 ................................................. 24.5 2.6 6.7 7.4 2.9 2.1 1.4 1.3 7.07

2 ................................................. 25.8 1.5 5.9 7.6 3.5 2.6 2.3 2.3 6.49

3 ................................................. 13.9 0.7 2.4 4.0 2.0 1.5 1.6 1.7 8.66

4 ................................................. 7.4 0.3 0.9 2.3 1.2 1.1 0.8 0.9 12.06

5 or More.................................... 7.5 Q 0.7 1.4 1.0 1.2 1.1 2.0 11.81

More than 12 Hours per Day

None........................................... 70.4 6.2 16.1 19.9 8.9 6.9 5.6 6.9 3.98

1 ................................................. 15.7 1.0 3.9 5.1 1.9 1.5 1.2 1.1 9.23

2 ................................................. 6.3 0.2 1.2 1.7 0.9 0.7 0.8 0.7 12.35

3 ................................................. 2.4 Q 0.4 0.7 0.5 0.2 0.2 0.3 21.42

4 ................................................. 1.0 Q Q 0.2 0.1 Q 0.1 0.2 30.54

5 or More.................................... 0.8 Q Q 0.2 Q Q 0.2 0.1 33.47

See footnotes at end of table.

18

Energy Information Administration/Energy Consumption Series 

Residential Lighting: Use and Potential Savings
Table 4.1. Light Usage by Heated Floorspace Category, 

Million U.S. Households, 1993 Continued

Housing Unit and Household 

Characteristics

HSE Column Factor:

Total

0.4

Heated Floorspace Category 

(square feet)

Fewer

than

600

1.7

600 

to 

999

0.9

1,000

to 

1,599

0.8

1,600

to 

1,999

1.1

2,000

to 

2,399

1.2

2,400

to 

2,999

1.2

3,000

or 

More

1.2

RSE

Row

Factors

Fluorescent Lights Used

1 to 4 Hours per Day

None........................................... 75.5 6.4 18.3 21.8 9.5 7.0 6.0 6.5

1 ................................................. 16.1 1.0 2.9 4.8 2.3 1.9 1.5 1.7

2 ................................................. 3.8 Q 0.5 1.0 0.5 0.4 0.5 0.7

3 or More.................................... 1.2 Q Q 0.2 0.2 0.3 0.1 0.3

4 to 12 Hours per Day

None........................................... 75.1 6.6 18.6 21.9 9.0 7.0 5.9 6.1

1 ................................................. 15.9 0.8 2.5 4.6 2.5 1.8 1.7 2.0

2 ................................................. 4.3 Q 0.6 1.1 0.6 0.5 0.5 0.9

3 or More.................................... 1.4 Q Q 0.2 0.2 0.3 0.2 0.3

More than 12 Hours per Day 

None........................................... 88.2 7.2 20.5 25.4 11.0 8.7 7.4 8.1

1 ................................................. 6.7 0.2 1.1 2.0 1.3 0.6 0.6 0.9

2 ................................................. 1.1 Q Q 0.2 Q 0.3 0.1 0.2

3 or More .................................... 0.6 Q Q 0.2 Q Q Q 0.1

Compact Fluorescent Light 

Bulbs Used

Yes ............................................... 8.6 0.4 1.2 2.1 1.3 1.1 1.1 1.3

No................................................. 88.1 7.1 20.6 25.7 11.1 8.5 7.1 7.9

Halogen Light Bulbs Used

Yes ............................................... 11.2 0.5 1.6 2.9 1.7 1.6 1.2 1.8

No................................................. 85.4 7.0 20.2 24.9 10.7 8.1 7.0 7.5

Outdoor Lights

Yes (more than one

may apply)...................................... 63.5 2.6 11.5 18.8 9.6 7.1 6.5 7.5

Evening Only................................ 25.9 0.9 3.9 7.6 3.9 3.1 3.0 3.6

All Night ........................................ 16.6 0.7 3.3 5.1 2.6 1.7 1.6 1.7

Automatic Control......................... 18.2 0.3 2.2 4.7 3.3 2.5 2.3 2.9

High Intensity ............................... 3.2 Q 0.4 0.9 0.4 0.4 0.6 0.4

All Wattage Less than 150 ........... 31.5 1.5 6.8 9.8 4.8 3.2 2.6 2.8

Gaslight1 .................................... 0.6 Q Q Q Q Q Q 0.2

No................................................... 33.1 4.9 10.3 9.0 2.8 2.5 1.7 1.8

4.21

8.48

16.20

26.77

4.20

8.49

14.72

25.48

3.76

14.16

28.48

36.44

11.20

3.79

9.89

3.87

4.89

7.31

8.87

8.90

22.60

8.23

35.99

7.47

1 Gas includes LPG and natural gas.

Q = Data withheld either because the Relative Standard Error (RSE) was greater than 50 percent or fewer than 10 households were sampled.

Notes: • To obtain the RSE percentage for any table cell, multiply the corresponding column and row factors. • Because of rounding, data may not sum to totals. 

• See "Glossary" for definition of terms used in this report

Source: Energy Information Administration, Office of Energy Markets and End Use, Forms EIA-457 A-C, E, and H of the 1993 Residential Energy Consumption 

Survey. (For specific titles of forms, see Appendix A.)

Energy Information Administration/Energy Consumption Series 

Residential Lighting: Use and Potential Savings 19
Table 4.2. Light Usage by Heated Floorspace Category, 

Percent of U.S. Households, 1993

Housing Unit and Household 

Characteristics

RSE Column Factor:

Total

0.4

Fewer

than

600

1.6

Heated Floorspace Category 

(square feet)

600 

to 

999

0.9

1,000 

to

1,599

0.8

1,600

to 

1,999

1.1

2,000

to 

2,399

1.2

2,400

to 

2,999

1.3

3,000

or 

More

1.2

RSE

Row

Factors

Total................................................. 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 0.0

Indoor Electric Lights 

Total Number Lights

1 to 4 Hours

None........................................... 10.0 16.5 10.2 9.9 9.2 9.4 9.1 6.7 11.42

1 ................................................. 22.9 31.3 30.9 23.5 19.9 15.3 17.9 11.5 6.62

2 ................................................. 28.4 32.3 31.9 28.7 28.7 24.8 26.0 21.5 5.64

3 ................................................. 17.4 10.5 15.4 18.7 17.9 20.5 18.0 19.4 7.72

4 ................................................. 9.5 5.8 6.2 9.1 11.6 11.8 12.2 13.7 10.88

5 or More.................................... 11.9 3.6 5.4 10.1 12.7 18.1 16.8 27.1 10.17

4 to 12 Hours

None........................................... 13.9 26.7 19.4 14.0 9.0 9.2 7.7 7.3 9.57

1 ................................................. 21.6 32.3 29.0 22.6 18.8 14.9 13.7 10.1 6.97

2 ................................................. 27.4 23.6 28.9 27.9 29.3 26.1 27.8 23.4 5.52

3 ................................................. 17.3 10.3 13.5 18.2 20.9 20.3 20.7 18.3 6.99

4 ................................................. 9.5 5.2 5.0 10.2 11.0 12.3 12.9 13.7 9.94

5 or More.................................... 10.4 Q 4.3 7.1 11.1 17.2 17.2 27.3 9.39

More than 12 Hours per Day

None........................................... 68.7 80.3 70.6 67.3 66.0 67.6 63.3 68.2 2.44

1 ................................................. 17.2 14.1 19.1 19.3 16.5 14.7 16.1 13.2 8.16

2 ................................................. 7.9 3.6 6.8 7.6 9.7 9.3 11.4 7.8 11.69

3 ................................................. 3.5 Q 2.4 3.2 4.7 5.1 3.4 5.0 17.11

4 ................................................. 1.5 Q 0.7 1.3 1.9 1.7 3.1 3.1 25.65

5 or More .................................... 1.2 Q Q 1.2 1.0 1.6 2.6 2.6 27.85

Incandescent Lights Used

1 to 4 Hours per Day

Nona........................................... 15.3 21.0 15.9 14.8 14.7 14.9 16.0 10.9 9.22

1 ................................................. 25.2 34.4 31.8 26.1 22.3 17.6 20.1 15.6 6.11

2 ................................................. 26.2 27.4 28.5 27.3 26.6 24.5 21.4 22.2 5.50

3 ................................................. 15.9 9.1 13.9 16.4 17.2 18.7 18.2 17.8 7.89

4 ................................................. 7.8 4.6 5.1 7.7 9.6 9.9 10.5 9.7 12.01

5 or More.................................... 9.7 3.6 4.8 7.7 9.6 14.4 13.8 23.7 11.43

4 to 12 Hours per Day

None........................................... 18.0 31.0 23.6 18.0 14.5 11.2 11.7 11.4 8.06

1 ................................................. 25.4 34.5 30.9 26.6 23.6 22.3 17.3 14.3 6.32

2 ................................................. 26.7 19.9 26.8 27.5 28.4 27.5 28.3 25.2 5.60

3 ........................ ........... ....... 14.4 9.5 11.1 14.3 16.3 15.5 19.9 18.1 8.08

4 ................................................. 7.7 3.7 4.3 8.3 9.3 11.0 9.6 9.7 11.42

5 or More.................................... 7.8 Q 3.3 5.2 7.9 12.6 13.1 21.4 10.85

More than 12 Hours per Day

None........................................... 72.9 82.6 74.0 71.6 71.5 71.6 68.0 73.8 2.20

1 ................................................. 16.3 13.2 17.8 18.4 15.4 15.6 14.7 12.2 8.36

2 ............................................. 6.6 3.1 5.7 6.0 7.5 7.7 10.1 7.6 12.11

3 ................................................. 2.5 Q 1.9 2.5 3.7 2.5 3.0 3.0 20.94

4 ................................................. 1.0 Q Q 0.8 1.2 Q 1.7 2.4 30.13

5 or More.................................... 0.8 Q Q 0.7 Q Q 2.5 1.0 32.03

See footnotes at end of table.

20

Energy Information Administration/Energy Consumption Serle 

Residential Lighting: Use and Potential Savings
Table 4.2. Light Usage by Heated Floorspace Category, 

Percent of U.S. Households, 1993 Continued

Housing Unit and Household 

Characteristics

RSE Column Factor:

Total

0.4

Heated Floorspace Category 

(square feet)

Fewer 

than 

600

1.6

600 

to 

999

0.9

1,000

to 

1,599

0.8

1,600

to 

1,999

1.1

2,000

to 

2,399

1.2

2,400

to 

2,999

1.3

3,000

or 

More

1.2

RSE

Row

Factors

Fluorescent Lights Used 

1 to 4 Hours per Day

None ........................................... 78.2 84.8 84.1 78.5 76.5 73.0 73.3 70.0

1 ................................................. 16.6 13.5 13.3 17.1 18.2 19.5 18.7 18.5

2 ................................................. 3.9 Q 2.3 3.6 3.9 4.4 6.4 7.9

3 or More .................................... 1.3 Q Q 0.8 1.3 3.2 1.7 3.6

4 to 12 Hours per Day

None ........................................... 77.7 87.5 85.5 78.7 72.8 73.1 71.3 65.3

1 ................................................. 16.4 10.3 11.5 16.4 20.6 18.8 20.5 21.6

2 ................................................. 4.4 Q 2.7 4.0 4.8 4.7 5.9 9.5

3 or More.................................... 1.5 Q Q 0.8 1.8 3.4 2.3 3.6

More than 12 Hours per Day 

None........................................... 91.3 95.8 93.9 91.5 88.4 90.3 90.1 87.0

1 ................................................. 6.9 3.2 5.3 7.0 10.4 6.4 7.0 9.5

2 ................................................. 1.1 Q Q 0.7 Q 2.7 1.7 1.9

3 or More.................................... 0.6 Q Q 0.8 Q Q Q 1.5

Compact Fluorescent Light 

Bulbs Used

Yes ............................................... 8.9 5.6 5.6 7.5 10.4 11.9 13.0 14.5

No................................................. 91.1 94.4 94.4 92.5 89.6 88.1 87.0 85.5

Halogen Light Bulbs Used

Yes ............................................... 11.6 6.8 7.2 10.3 14.0 16.3 15.0 19.0

No................................................. 88.4 93.2 92.8 89.7 86.0 83.7 85.0 81.0

Outdoor Lights

Yes (more than one

may apply) ...................................... 65.8 35.1 52.6 67.6 77.3 74.0 79.0 80.3

Evening Only ................................ 26.9 12.4 18.1 27.2 31.2 31.7 36.6 38.7

All Night ........................................ 17.2 8.7 15.2 18.5 20.6 17.6 18.9 17.8

Automatic Control......................... 18.8 4.4 10.1 17.0 26.2 25.9 28.2 31.2

High Intensity ............................... 3.3 Q 2.0 3.2 3.4 4.1 7.S 3.8

All Wattage Less than 150 ........... 32.6 20.3 31.0 35.3 38.8 33.0 31.5 30.1

Gaslight1 .................................... 0.6 Q Q Q Q Q Q 1.7

No................................................... 34.2 64.9 47.4 32.4 22.7 26.0 21.0 19.7

1.96

7.94

15.67

26.57

1.97

7.95

14.21

24.83

1.18

13.86

27.40

35.79

10.72

1.27

9.31

1.46

3.11

6.28

8.25

8.37

22.33

7.00

35.22

6.47

1 Gas includes LPG and natural gas.

Q = Data withheld either because the Relative Standard Error (RSE) was greater than 50 percent or fewer than 10 households were sampled.

Notes: • To obtain the RSE percentage for any table cell, multiply the corresponding column and row factors. • Because of rounding, data may not sum to totals. 

• See "Glossary" for definition of terms used in this report

Source: Energy Information Administration, Office of Energy Markets and End Use, Forms EIA-457 A-C, E, and H of the 1993 Residential Energy Consumption 

Survey. (For specific titles of forms, see Appendix A.)

Energy Information Administration/Energy Consumption Series 

Residential Lighting: Use and Potential Savings 21
Table 4.3. Light Usage by Total Number of Rooms, 

Million U.S. Households, 1993

Housing Unit and Household 

Characteristics

RSE Column Factor:

Total

0.4

Total Number of Rooms

(excluding bathrooms)

1 or 2

2.9

3to5

0.7

6 to 8

0.7

9 or

More

1.7

Total....................................................... 96.6 3.2 47.4 40.2 5.8

RSE

Row 

Factors

3.59

Indoor Electric Lights 

Total Number Lights 

1 to 4 Hours

None .................................................

1 .......................................................

2 .......................................................

3 .......................................................

4 .......................................................

4 to 12 Hours

Non© 1 .......................................................

2 .......................................................

3 .......................................................

4 .......................................................

More than 12 Hours per Day

None.................................................

1 .......................................................

2 .......................................................

3 .......................................................

4 .......................................................

Incandescent Lights Used 

1 to 4 Hours per Day

None.................................................

1 .......................................................

2 .......................................................

3 .......................................................

4 .......................................................

5 or More ..........................................

4 to 12 Hours per Day

1 .......................................................

2 .......................................................

3 .......................................................

4 .......................................................

More than 12 Hours per Day

None.................................................

1 .......................................................

2 .......................................................

3 .......................................................

4 .......................................................

5 or More ..........................................

9.6

22.1

27.4

16.8

9.2

11.5

13.4

20.8

26.4

16.7

9.2

10.0

66.4

16.6

7.6

3.3

1.5

1.2

14.8

24.4

25.3

15.3

7.5

9.4

17.4

24.5

25.8

13.9

7.4

7.5

70.4

15.7

6.3

2.4

1.0

0.8

0.5

1.2

0.9

0.4

Q

Q

0.9

1.1

0.8

0.3

Q

Q

2.6

0.4

Q

Q

Q

Q

0.7

1.3

0.8

0.3

Q

Q

1.0

1.2

0.6

0.2

Q

Q

2.7

0.4

Q

Q

Q

Q

5.0

13.1

14.9

7.8

3.2

0 A

8.1

13.0

13.7

7.2

3.1

2.3

33.9

8.4

3.0

1.2

0.5

0.4

7.5

14.2

13.6

6.6

2.6

2.8

10.0

14.4

12.9

5.9

2.5

1.7

35.5

8.1

2.4

0.9

0.3

0.2

3.8

7.2

10.4

7.5

5.1

6.2

4.1

6.3

10.7

8.1

5.1

6.0

26.1

7.1

3.8

1.8

0.8

0.6

6.0

8.0

9.6

7.4

4.2

5.0

5.8

8.1

10.9

6.9

4.1

4.4

28.2

6.5

3.3

1.2

0.6

0.4

0.3

0.6

1.2

1.1

0.8

1.7

0.4

0.5

1.3

1.1

0.8

1.7

3.7

0.6

0.7

0.3

0.2

0.2

0.6

0.8

1.3

1.1

0.6

1.5

0.6

0.9

1.4

0.9

0.7

1.4

4.1

0.7

0.6

0.2

Q

0.2

11.81

6.84

6.27

7.77

10.88

10.07

9.79

6.33

6.04

7.33

8.41

8.84

4.04

8.52

10.83

16.40

24.08

26.11

9.54

6.26

6.16

8.16

11.81

11.42

8.31

6.16

6.04

8.20

10.55

10.46

3.81

9.53

10.68

20.55

31.05

30.23

See footnotes at end of table.

22

Energy Information Administration/Energy Consumption Series 

Residential Lighting: Use and Potential Savings
Table 4.3. Light Usage by Total Number of Rooms,

Million U.S. Households, 1993 — Continued

Housing Unit and Household 

Characteristics

RSE Column Factor:

Total

0.4

Total Number of Rooms 

(excluding bathrooms)

1 or 2

2.9

3 to 5

0.7

6 to 8

0.7

9 or 

More

1.7

RSE

Row

Factors

Fluorescent Lights Used

1 to 4 Hours per Day

None................................................. 75.5

1 ....................................................... 16.1

2 ....................................................... 3.8

3 or More .......................................... 1.2

4 to 12 Hours per Day

None ................................................. 75.1

1 ....................................................... 15.9

2 ....................................................... 4.3

3orMore .......................................... 1.4

More than 12 Hours per Day 

None................................................. 88.2

1 ....................................................... 6.7

2 ....................................................... 1.1

3 or More .......................................... 0.6

Compact Fluorescent Light 

Bulbs Used

Yes ..................................................... 8.6

No....................................................... 88.1

Halogen Light Bulbs Used

Yes ..................................................... 11.2

No....................................................... 85.4

Outdoor Lights

Yes (more than one

may apply)............................................ 63.5

Evening Only ...................................... 25.9

All Night.............................................. 16.6

Automatic Control............................... 18.2

High Intensity ..................................... 3.2

All Wattage Less than 150 ................. 31.5

Gas Light 1 .......................................... 0.5

No......................................................... 33.1

2.8 

0.4 

Q 

Q

2.8 

0.3 

Q 

Q

3.1 

Q 

Q 

Q

0.2 

3.1

0.2 

3.0

0.9 

0.3 

0.3 

0.1 

Q 

0.5 

Q 

2.4

38.4 

7.4 

1.3 

0.3

39.2 

6.7 

1.2 

0.3

44.3 

2.7 

0.3 

0.2

3.0 

44.4

4.4 

42.9

27.2 

9.6 

7.3 

5.7 

1.0

15.7 

Q

20.2

30.3 

7.3 

2.0 

0.6

29.2 

7.8 

2.5 

0.8

36.0 

3.4 

0.5 

0.3

4.4 

35.8

5.5 

34.7

30.8

13.7

7.9

10.4

1.8

13.7

0.3

9.4

4.0 

1.1 

0.5 

0.2

3.9 

1.1 

0.5 

0.3

4.9 

0.6 

0.3 

Q

1.0 

4.8

1.2 

4.7

4.7 

2.4 

1.2 

2.0 

0.3 

1.6 

0.2 

1.1

4.01

8.29

14.15

24.63

4.01

8.50

12.88

25.13

3.76

13.55

25.05

40.52

11.13

3.85

9.64

3.95

4.98

7.86

8.53

8.05

22.64

8.51

31.23

6.84

1 Gas includes LPG and natural gas.

Q = Data withheld either because the Relative Standard Error (RSE) was greater than 50 percent or (ewer than 10 households were sampled.

Notes: • To obtain the RSE percentage for any table cell, multiply the corresponding column and row factors. • Because of founding, data may not sum 

to totals. • See "Glossary" for definition of terms used in this report.

Source: Energy Information Administration, Office of Energy Markets and End Use, Forms EIA-457 A-C, E, and H of the 1993 Residential Energy 

Consumption Survey. (For specific titles of forms, see Appendix A.)

Energy Information Administration/Energy Consumption Series 

Residential Lighting: Use and Potential Savings 23
Table 4.4. Light Usage by Total Number of Rooms, 

Percent of U.S. Households, 1993

Housing Unit and Household 

Characteristics

RSE Column Factor:

Total

0.5

1 or 2

2.6

Total Number of Rooms 

(excluding bathrooms)

3to5

0.7

6 to 8

9 or 

More

0.7 1.6

RSE

Row

Factors

Total....................................................... 100.0

Indoor Electric Lights 

Total Number Lights

1 to 4 Hours

None................................................. 10.0

1 ....................................................... 22.9

2 ....................................................... 28.4

3 ....................................................... 17.4

4 ....................................................... 9.5

SorMore.......................................... 11.9

4 to 12 Hours

None................................................. 13.9

1 ....................................................... 21.6

2 ....................................................... 27.4

3 ....................................................... 17.3

4 ....................................................... 9.5

SorMore.......................................... 10.4

More than 12 Hours per Day

None................................................. 68.7

1 ....................................................... 17.2

2 ....................................................... 7.9

3 ....................................................... 3.5

4 ....................................................... 1.S

SorMore .......................................... 1.2

Incandescent Lights Used 

1 to 4 Hours per Day

None ................................................. 15.3

1 ....................................................... 25.2

2 ....................................................... 26.2

3 ....................................................... 15.9

4 ....................................................... 7.8

SorMore .......................................... 9.7

4 to 12 Hours per Day

None................................................. 18.0

1 ....................................................... 25.4

2 ....................................................... 26.7

3 ....................................................... 14.4

4 ....................................................... 7.7

SorMore .......................................... 7.8

More than 12 Hours per Day

None................................................. 72.9

1 ....................................................... 16.3

2 ....................................................... 6.6

3 ....................................................... 2.5

4 ....................................................... 1.0

SorMore .......................................... 0.8

100.0

16.8 

36.5 

29.3 

11.1

Q

Q

27.4 

33.8 

24.1

9.8

Q

Q

81.8

13.6

Q

Q

Q

Q

21.1 

40.0 

23.6

9.5

Q

Q

31.3 

37.6 

20.0

6.6

Q

Q

83.9 

13.8

Q

Q

Q

Q

100.0

10.5

27.7

31.4

16.5

6.7

7.1

17.1

27.4

28.9

15.2

6.6

4.8

71.6

17.8

6.4

2.5

1.0

0.8

15.8

30.0

28.7

13.9

5.6

5.9

21.1

30.4

27.1

12.5

5.3

3.6

74.8

17.1

5.0

1.9

0.7

0.5

100.0

9.4

17.8

25.8

18.7

12.8

15.5

10.2

15.6

26.6

20.1

12.7

14.8

64.8

17.8

9.5

4.5

2.0

1.4

14.9

20.0

24.0

18.3

10.5

12.3

14.4

20.1

27.1

17.2

10.3

10.9

70.2

16.3

8.2

3.1

1.4

0.9

100.0

5.8

10.7

21.1

19.0

13.5

29.8

6.3

8.9

21.5

19.0

14.4

29.9

64.2

10.3

11.8

5.9

3.7

4.2

10.2

13.7

22.3

19.0

9.5

25.3

9.7

15.2

24.3

15.6

11.4

23.7

69.7 

11.2 

10.9

4.1

Q

2.7

0.0

11.52

5.96

5.33

7.20

10.03

8.94

9.05

5.94

4.72

6.57

7.89

7.77

2.48

8.10

9.90

15.29

23.54

25.14

9.11

5.28

5.44

7.14

11.17

10.24

7.64

5.51

4.82

7.61

9.85

9.41

2.21

9.24

9.80

19.52

29.36

29.29

See footnotes at end of table.

24

Energy Information Administration/Energy Consumption Series 

Residential Lighting: Use and Potential Savings
Table 4.4. Light Usage by Total Number of Rooms,

Percent of U.S. Households, 1993 — Continued

Housing Unit and Household 

Characteristics

RSE Column Factor:

Total

0.5

Total Number of Rooms 

(excluding bathrooms)

1 or 2

2.6

3 to 5

0.7

6 to 8

0.7

9 or 

More

1.6

RSE

Row

Factors

Fluorescent Lights Used

1 to 4 Hours per Day

None................................................. 78.3

1 ....................................................... 16.6

2 ....................................................... 3.9

3 or More .......................................... 1.3

4 to 12 Hours per Day 

None................................................. 77.7

1 ....................................................... 16.4

2 ....................................................... 4.4

3 or More .......................................... 1.5

More than 12 Hours per Day 

None................................................. 91.3

1 ....................................................... 6.9

2 ....................................................... 1.1

3 or More .......................................... 0.6

Compact Fluorescent Light 

Bulbs Used

Yes ..................................................... 8.9

No....................................................... 91.1

Halogen Light Bulbs Used

Yes..................................................... 11.6

No....................................................... 88.4

Outdoor Lights

Yes (more than one

may apply)............................................ 65.8

Evening Only ...................................... 26.9

All Night.............................................. 17.2

Automatic Control............................... 18.8

High Intensity ..................................... 3.3

All Wattage Less than 150 ................. 32.6

Gas Light 1 .......................................... 0.6

No......................................................... 34.2

86.6 

11.3 

Q 

Q

88.3 

9.0 

Q 

Q

95.7 

Q 

Q 

Q

Q 

95.2

6.1 

93.9

26.6 

8.2 

8.7 

4.6 

Q

16.7 

Q

73.4

81.0

15.5

2.7

0.7

82.7

14.2

2.6

0.6

93.4 

5.6 

0.6 

0.4

6.2 

93.8

9.4 

90.6

57.4 

20.4 

15.4 

12.0

2.1 

33.1

Q 

42.6

75.5

18.0

4.9

1.6

72.6

19.3

6.1

2.0

89.5 

8.4 

1.3 

0.8

11.0

89.0

13.6

86.4

76.5

34.0

19.6

25.9

4.6

34.1

0.7

23.5

69.0

18.8

8.2

4.0

66.8

18.9

9.2

5.2

84.2 

9.4 

4.8

Q

17.7

82.3

19.7

80.3

81.1

40.5

19.7

33.5

4.8

26.6

2.6

18.9

1.76

7.57

13.62

23.96

1.76

7.70

12.31

24.44

1.19

12.64

24.39

38.36

9.30

1.30

9.47

1.35

3.37

6.78

7.63

7.50

21.66

7.72

30.03

5.64

1 Gas includes LPG and natural gas.

Q = Data withheld either because the Relative Standard Error (RSE) was greater than 50 percent or fewer than 10 households were sampled.

Notes: • To obtain the RSE percentage for any table cell, multiply the corresponding column and row factors. • Because of founding, data may not sum 

to totals. • See 'Glossary* for definition of terms used in this report.

Source: Energy Information Administration, Office of Energy Markets and End Use, Forms EIA-457 A-C, E, and H of the 1993 Residential Energy 

Consumption Survey. (For specific titles of forms, see Appendix A.)

Energy Information Administration/Energy Consumption Series 

Residential Lighting: Use and Potential Savings 25
Table 4.5. Light Usage by Family Income Category, 

Million U.S. Households, 1993

Housing Unit and Household

Characteristics

RSE Column Factor:

Total

0.4

1993 Family Income Category

Less

than

$5,000

1.9

$5,000

to

$9,999

1.2

$10,000

to

$14,999

1.1

$15,000

to

$19,999

1.2

$20,000

to

$24,999

1.2

$25,000

to

$34,999

0.9

$35,000

to

$49,999

0.8

$50,000

to

$74,999

0.9

$75,000

or

More

1.2

Total ............................................... 96.6 4.1 10.6 11.1 9.6 8.7 14.1 17.5 12.6 8.3

RSE

Row 

Factors

3.98

Indoor Electric Lights 

Total Number Lights 

1 to 4 Hours

1 ................................................

2 ................................................

3 ................................................

4 ................................................

4 to 12 Hours

1 ................................................

2 ................................................

3 ................................................

4 ................................................

More than 12 Hours per Day

1 ................................................

2 ................................................

3................................................

4 ................................................

Incandescent Lights Used 

1 to 4 Hours per Day

1 ................................................

2 ................................................

3 ...... . . .. ..............

4 ......

4 to 12 Hours per Day

1 ................................................

2 ...... ... ........ .. ..................

3 ................................................

4 ...... .. ........ ......................

More than 12 Hours per Day

1 ................................................

2 ................................................

3 ................................................

4 ................................................

9.6

22.1

27.4

16.8

9.2

11.5

13.4

20.8

26.4

16.7

9.2

10.0

66.4

16.6

7.6

3.3

1.5

1.2

14.8

24.4

25.3

15.3

7.5

9.4

17.4

24.5

25.8

13.9

7.4

7.5

70.4

15.7

6.3

2.4

1.0

0.8

0.8

1.5

0.9

0.5

0.2

0.2

1.0

1.3

1.0

0.4

0.2

0.2

2.7

0.9

0.4

Q

Q

Q

1.0

1.5

0.9

0.4

0.2

0.2

1.0

1.4

0.9

0.3

0.2

Q

2.8

0.9

0.3

Q

Q

Q

1.5

3.5

3.1

1.6

0.4

0.5

2.8

3.5

2.8

0.9

0.4

0.2

7.4

2.0

0.8

0.2

0.1

Q

2.1

3.7

2.7

1.3

0.3

0.5

3.2

3.7

2.5

0.8

0.3

0.1

7.8

1.9

0.6

0.1

0.1

Q

1.4

3.3

3.3

1.6

0.8

0.8

2.1

3.2

3.0

1.6

0.6

0.5

7.8

1.9

0.8

0.4

0.1

Q

2.0

3.5

2.9

1.5

0.6

0.7

2.7

3.3

3.0

1.3

0.5

0.4

8.2

1.8

0.7

0.4

Q

Q

1.0

2.7

2.9

1.5

0.8

0.7

1.5

2.3

2.5

1.8

1.0

0.6

6.2

2.0

0.8

0.4

Q

Q

1.5

2.9

2.6

1.4

0.6

0.6

2.1

2.5

2.3

1.6

0.7

0.5

6.7

1.9

0.8

0.1

Q

Q

0.9

2.0

3.2

1.4

0.6

0.7

1.2

2.0

2.6

1.5

0.8

0.6

6.3

1.5

0.6

0.1

Q

Q

1.5

2.2

2.7

1.2

0.6

0.5

1.6

2.3

2.5

1.3

0.6

0.4

6.5

1.5

0.4

0.1

Q

Q

1.3

3.4

3.8

2.4

1.2

1.9

1.8

2.8

4.4

2.5

1.3

1.4

9.6

2.2

1.3

0.6

0.2

0.2

2.0

3.6

3.5

2.3

1.1

1.5

2.3

3.5

4.1

1.9

1.1

1.1

10.4

1.9

1.0

0.5

Q

0.2

1.3

2.8

4.9

3.5

2.3

2.6

1.3

3.2

4.9

3.9

2.1

2.1

11.9

2.9

1.3

0.7

0.4

0.2

2.0

3.4

4.8

3.3

1.9

2.1

1.9

4.1

5.2

3.2

1.5

1.6

12.7

2.8

1.2

0.5

0.2

Q

1.0

1.8

3.3

2.6

1.7

2.2

1.1

1.7

3.4

2.7

1.6

2.2

8.5

2.2

0.9

0.5

0.3

0.2

1.6

2.2

3.2

2.6

1.3

1.8

1.6

2.5

3.4

2.2

1.4

1.5

9.2

2.0

0.8

0.4

Q

0.1

0.5

1.2

2.0

1.6

1.2

1.9

0.7

0.9

1.7

1.5

1.3

2.2

5.9

1.1

0.6

0.3

Q

0.2

0.9

1.4

2.1

1.4

1.0

1.5

0.9

1.3

1.9

1.4

0.9

1.8

6.2

1.1

0.6

0.2

Q

Q

12.52

7.83

7.22

9.18

13.02

13.17

10.40

8.06

7.19

9.14

12.49

13.58

4.61

9.54

12.83

20.85

30.65

33.07

9.96

7.50

7.26

9.61

14.38

15.00

8.96

7.38

7.09

10.25

14.14

15.76

4.38

9.98

13.77

23.84

32.58

36.41

See loo (notes at end of table.

26

Energy Information Administration/Energy Consumption Series 

Residential Lighting: Use and Potential Savings
Table 4.5. Light Usage by Family Income Category,

Million U.S. Households, 1993 Continued

Housing Unit and Household

Characteristics

RSE Column Factor:

Total

0.4

1993 Family Income Category

Less

than

$5,000

1.9

$5,000

to

$9,999

1.2

$10,000

to

$14,999

1.1

$15,000

to

$19,999

1.2

$20,000

to

$24,999

1.2

$25,000

to

$34,999

0.9

$35,000

to

$49,999

0.8

$50,000

to

$74,999

0.9

$75,000

or

More

1.2

RSE

Row

Fluorescent Lights Used 

1 to 4 Hours per Day

1 ...............................................

2 ................................................

4 to 12 Hours per Day

None .........................................

1 ...............................................

2 ...............................................

More than 12 Hours per Day 

None ........................................

1

2...............................................

Compact Fluorescent Light 

Bulbs Used

Yes.............................................

No ..............................................

Halogen Light Bulbs Used

Yes.............................................

No ..............................................

Outdoor Lights

Yes (more than one 

may apply) ...................................

All Night .....................................

High Intensity .............................

All Wattage Less than 150 .........

Gas Light1 ..................................

No ................................................

75.5

16.1

3.8

1.2

75.1

15.9

4.3

1.4

88.2

6.7

1.1

0.6

8.6

88.1

11.2

85.4

63.5

25.9

16.6

18.2

3.2

31.5

0.5

33.1

3.5

0.5

Q

Q

3.6

0.4

Q

Q

3.8

0.3

Q

Q

0.3

3.8

0.4

3.7

1.8

0.6

0.5

0.4

Q

1.1

Q

2.2

8.9

1.3

0.4

Q

9.4

1.0

0.1

Q

9.9

0.6

Q

Q

0.4

10.2

0.3

10.3

5.3

1.7

1.5

0.8

0.1

3.0

Q

5.3

9.1

1.7

0.2

Q

9.4

1.2

0.4

Q

10.4

0.6

Q

Q

0.5

10.6

0.7

10.5

6.3

2.1

1.9

1.3

0.3

3.5

Q

4.8

7.8

1.4

0.4

Q

7.6

1.4

0.5

Q

8.8

0.6

Q

Q

0.6

9.0

0.7

8.9

6.3

2.4

1.8

1.7

0.3

3.2

Q

3.4

6.9

1.4

0.3

0.2

6.9

1.6

0.2

Q

8.2

0.5

Q

Q

0.8

8.0

1.1

7.7

5.6

2.2

1.3

1.5

0.2

3.1

Q

3.2

11.0

2.4

0.5

0.2

11.0

2.4

0.5

0.2

12.6

1.2

0.2

Q

1.1

12.9

1.6

12.4

9.6

3.6

2.8

2.5

0.5

4.7

Q

4.5

13.5

3.0

0.6

0.3

12.8

3.5

0.9

0.2

15.8

1.4

Q

0.2

2.0

15.5

2.8

14.7

12.4

5.7

2.8

3.9

0.8

6.0

0.2

5.0

9.1

2.6

0.7

0.2

8.8

2.6

0.9

0.4

11.2

1.0

0.4

Q

1.6

11.0

2.0

10.6

9.9

4.6

2.2

3.4

0.5

4.3

Q

2.8

5.8

1.7

0.7

0.2

5.6

1.8

0.7

0.3

7.6

0.6

Q

Q

1.2

7.1

1.8

6.6

6.5

3.0

1.8

2.6

0.4

2.6

Q

1.9

4.50

9.50

20.47

30.43

4.47

9.84

18.81

28.07

4.08

15.45

32.32

40.38

12.95

4.13

12.07

4.17

5.41

8.30

9.27

9.51

25.70

8.22

43.65

7.22

1 Gas includes LPG and natural gas.

Q = Data withheld either because the Relative Standard Error (RSE) was greater than 50 percent or fewer than 10 households were sampled.

Notes: • To obtain the RSE percentage for any table cell, multiply the corresponding column and row factors. • Because of founding, data may not sum to totals. 

• See "Glossary* for definition of terms used in this report.

Source: Energy Information Administration, Office of Energy Markets and End Use, Forms EIA-457 A-C, E, and H of the 1993 Residential Energy Consumption 

Survey. (For specific titles of forms, see Appendix A.)

Energy Information Administration/Energy Consumption Serie 

Residential Ughting: Use and Potential Savings 27
Table 4.6. Light Usage by Family Income Category, 

Percent of U.S. Households, 1993

Housing Unit and Household 

Characteristics

RSE Column Factor:

Total

0.4

1993 Family Income Category

Less

than

$5,000

1.8

$5,000

to

$9,999

1.2

$10,000

to

$14,999

1.1

$15,000

to

$19,999

1.1

$20,000

to

$24,999

1.2

$25,000

to

$34,999

0.9

$35,000

to

$49,999

0.8

$50,000

to

$74,999

0.9

$75,000

or

More

1.1

Total ............................................... 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0

RSE

Row 

Factors

0.0

Indoor Electric Lights 

Total Number Lights 

1 to 4 Hours

1 ................................................

2 ................................................

3 ................................................

4 ................................................

4 to 12 Hours

1 ................................................

2 ..... ...... ....... .........

3 ..... ....... ...... ........

4 ................................................

More than 12 Hours per Day

1 ................................................

2 ................................................

3 ................................................

4 ................................................

Incandescent Lights Used 

1 to 4 Hours per Day

1 ................................................

2

3 ................................................

4

4 to 12 Hours per Day

1 ................................................

2 ................................................

3 ................................................

4 ................................................

More than 1 2 Hours per Day

1 ................................................

2 ................................................

3 ................................................

4 ................................................

10.0

22.9

28.4

17.4

9.5

11.9

13.9

21.6

27.4

17.3

9.5

10.4

68.7

17.2

7.9

3.5

1.5

1.2

15.3

25.2

26.2

15.9

7.8

9.7

18.0

25.4

26.7

14.4

7.7

7.8

72.9

16.3

6.6

2.5

1.0

0.8

18.7

35.8

23.2

11.4

5.4

5.5

23.7

31.7

25.4

9.4

5.3

4.6

66.2

21.1

10.1

Q

Q

Q

23.6

36.3

21.1

9.2

4.9

4.9

25.8

35.0

23.0

7.3

5.4

Q

68.5

21.8

7.9

Q

Q

Q

14.0

33.0

29.2

15.5

3.7

4.7

26.2

33.1

26.7

8.1

4.1

1.8

70.3

18.6

7.8

1.6

1.2

Q

20.2

34.5

25.2

12.6

3.0

4.3

30.4

34.6

23.3

7.5

3.2

1.0

73.6

17.9

5.7

1.3

1.3

Q

12.7

29.5

29.5

14.2

7.1

7.0

19.2

29.2

27.0

14.5

5.3

4.9

70.4

17.3

7.1

3.7

1.3

Q

18.4

31.2

26.2

13.1

5.2

6.0

24.3

29.3

27.0

11.4

4.3

3.6

73.9

15.8

5.9

3.3

Q

Q

10.0

28.4

30.1

15.9

7.9

7.7

15.3

23.8

25.7

18.9

10.2

6.0

64.8

20.6

8.8

4.3

Q

Q

15.8

30.1

26.9

14.7

6.3

6.2

21.7

25.7

23.8

16.2

7.4

5.2

69.4

19.3

8.7

1.3

Q

Q

10.2

22.6

36.4

16.3

6.4

8.0

14.2

23.1

30.1

16.9

8.9

6.9

71.7

17.0

7.2

1.6

Q

Q

17.6

25.2

31.2

13.9

6.4

5.8

18.3

26.1

28.9

15.0

7.3

4.5

74.3

17.6

4.7

1.5

Q

Q

9.0

24.1

27.3

17.4

8.9

13.4

12.7

19.6

31.2

17.5

9.0

10.0

68.2

15.6

9.1

4.2

1.6

1.3

14.5

25.8

25.0

16.0

7.9

10.8

16.6

24.8

29.4

13.4

8.2

7.7

74.0

13.7

7.0

3.3

Q

1.3

7.6

16.1

28.1

20.2

13.3

14.7

7.4

18.1

28.3

22.4

11.8

12.0

68.2

16.5

7.6

4.0

2.4

1.3

11.5

19.3

27.2

19.1

10.7

12.1

10.7

23.4

29.6

18.4

8.8

9.0

72.6

15.8

6.6

2.9

1.3

Q

8.0

13.9

26.4

20.8

13.2

17.6

8.6

13.4

26.8

21.2

12.6

17.4

67.1

17.8

7.5

4.0

2.1

1.6

12.3

17.8

25.2

20.3

10.0

14.4

12.6

20.2

26.6

17.4

11.1

12.1

72.8

16.0

6.2

3.0

Q

1.1

6.3

14.1

23.6

18.7

14.7

22.5

8.1

10.8

20.8

18.1

15.4

26.8

71.0

12.9

7.4

4.1

Q

2.8

11.4

16.9

25.3

16.8

11.9

17.7

11.0

15.9

23.2

17.0

11.0

21.7

74.1

13.4

7.2

2.9

Q

Q

12.08

6.91

6.07

8.22

12.67

12.40

9.68

7.07

6.32

8.17

11.70

12.97

2.66

8.70

12.41

20.14

29.96

31.97

9.25

6.50

6.28

8.71

14.08

14.27

8.18

6.35

6.11

9.39

13.64

15.09

2.36

9.04

13.47

23.27

31.84

34.33

See footnotes at end of table.

28

Energy Information Administration/Energy Consumption Serle 

Residential Lighting: Use and Potential Savings
Table 4.6. Light Usage by Family Income Category,

Percent of U.S. Households, 1993 Continued

Housing Unit and Household 

Characteristics

RSE Column Factor:

Total

0.4

1993 Family Income Category

Less

than

$5,000

1.8

$5,000

to

$9,999

1.2

$10,000

to

$14,999

1.1

$15,000

to

$19,999

1.1

$20,000

to

$24,999

1.2

$25,000

to

$34,999

0.9

$35,000

to

$49,999

0.8

$50,000

to

$74,999

0.9

$75,000

or

More

1.1

RSE

Row 

Factors

Fluorescent Lights Used 

1 to 4 Hours per Day

None .........................................

1 ................................................

2 ................................................

4 to 12 Hours per Day

1 ................................................

2 ................................................

More than 12 Hours per Day

1 ................................................

2 ................................................

Compact Fluorescent Light 

Bulbs Used

Yes..............................................

No ...............................................

Halogen Light Bulbs Used

Yes.............................................

No ..............................................

Outdoor Lights

Yes (more than one 

mav aoolv)

All Night .....................................

High Intensity .............................

All Wattage Less than 150 ..........

Gaslight1 ..................................

No ................................................

78.2

16.6

3.9

1.3

77.7

16.4

4.4

1.5

91.3

6.9

1.1

0.6

8.9

91.1

11.6

88.4

65.8

26.9

17.2

18.8

3.3

32.6

0.6

34.2

86.5

11.9

Q

Q

88.7

9.3

Q

Q

93.7

6.2

Q

Q

7.0

93.0

9.3

90.7

45.0

15.5

12.5

9.7

Q

26.3

Q

55.0

83.8

12.3

3.6

Q

88.7

9.1

1.3

Q

93.7

5.4

Q

Q

4.0

96.0

2.5

97.5

49.6

16.2

14.0

7.4

1.4

28.2

Q

50.4

82.2

14.9

2.1

Q

84.6

11.2

3.5

Q

93.9

5.3

Q

Q

4.8

95.2

6.0

94.0

56.9

19.0

17.4

11.9

2.5

31.8

Q

43.1

80.6

14.9

4.0

Q

79.1

14.9

5.2

Q

91.2

6.7

Q

Q

6.1

93.9

7.1

92.9

65.1

24.6

19.1

17.3

3.4

32.8

Q

34.9

78.5

16.3

3.4

1.8

78.3

18.2

2.5

Q

93.2

5.9

Q

Q

9.1

90.9

12.1

87.9

63.6

24.8

14.3

17.5

2.4

35.3

Q

36.4

78.2

17.3

3.3

1.2

78.1

17.2

3.4

1.3

89.4

8.6

1.4

Q

8.0

92.0

11.4

88.6

68.0

25.7

19.7

17.9

3.3

33.4

Q

32.0

77.3

17.5

3.7

1.6

73.4

19.9

5.3

1.4

90.3

7.7

Q

1.3

11.2

88.8

15.8

84.2

71.1

32.6

16.1

22.4

4.3

34.6

1.1

28.9

72.2

20.8

5.2

1.9

69.7

20.4

7.0

2.9

89.0

7.7

2.9

Q

13.0

87.0

16.1

83.9

78.2

36.8

17.5

27.3

4.3

33.9

Q

21.8

69.3

19.9

8.0

2.8

67.5

21.5

7.9

3.1

90.5

7.1

Q

Q

14.7

85.3

21.3

78.7

77.5

36.0

21.3

31.6

4.8

31.6

Q

22.5

2.10

8.78

20.05

29.78

1.99

9.04

18.43

27.51

1.17

14.85

30.93

38.59

12.32

1.20

11.22

1.37

3.42

7.23

8.46

8.59

25.01

7.27

41.61

6.27

1 Gas includes LPG and natural gas.

Q = Data withheld either because the Relative Standard Error (RSE) was greater than 50 percent or fewer than 10 households were sampled.

Notes: • To obtain the RSE percentage for any table cell, multiply the corresponding column and row factors. • Because of rounding, data may not sum to totals. 

• See "Glossary" for definition of terms used in this report. Source: Energy Information Administration, Office of Energy Markets and End Use, Forms EIA-457 A-C, E, and H of the 1993 Residential Energy Consumption 

Survey. (For specific titles of forms, see Appendix A.)

Energy Information Administration/Energy Consumption Series 

Residential Lighting: Use and Potential Savings 29
Table 4.7. Light Usage by Household Size, 

Million U.S. Households, 1993

Housing Unit and Household 

Characteristics

RSE Column Factor:

Total

0.4

Household Size

1 

Person

0.9

2

Persons

0.7

3 

Persons

1.0

4 

Persons

1.0

5 

Persons

1.5

6 or

More

Persons

2.2

RSE

Row

Factors

Total .................................................. 96.6

Indoor Electric Lights 

Total Number Lights 

1 to 4 Hours

None ............................................ 9.6

1 ................................................... 22.1

2................................................... 27.4

3................................................... 16.8

4................................................... 9.2

5 or More ..................................... 11.5

4 to 12 Hours

None ............................................ 13.4

1 ................................................... 20.8

2................................................... 26.4

3................................................... 16.7

4................................................... 9.2

5 or More ..................................... 10.0

More than 12 Hours per Day

None ............................................ 66.4

1 ................................................... 16.6

2................................................... 7.6

3................................................... 3.3

4................................................... 1.5

5 or More ..................................... 1.2

Incandescent Lights Used 

1 to 4 Hours per Day

None ............................................ 14.8

1 ................................................... 24.4

2................................................... 25.3

3................................................... 15.3

4................................................... 7.5

5 or More ..................................... 9.4

4 to 12 Hours per Day

None ............................................ 17.4

1 ................................................... 24.5

2................................................... 25.8

3................................................... 13.9

4................................................... 7.4

5 or More ..................................... 7.5

More than 12 Hours per Day

None ............................................ 70.4

1 ................................................... 15.7

2................................................... 6.3

3................................................... 2.4

4 ................................................... 1.0

5 or More ..................................... 0.8

23.5

3.2

7.5

7.6 

3.0 

1.1 

1.0

5.1 

7.2 

6.6 

2.6 

1.2 

0.8

17.8 

3.9 

1.1 

0.5

Q

Q

4.6 

7.8 

6.9 

2.4

1.0 

0.9

6.1 

8.1 

5.7 

2.3 

0.8 

0.5

18.5 

3.7 

0.8 

0.4

Q

Q

31.7

3.1 

7.4 

9.5 

5.7

3.0

3.1

4.0 

7.0 

8.9 

5.8 

3.0 

3.0

22.3 

5.0 

2.5 

1.0 

0.5 

0.3

5.3 

8.4 

8.4 

5.0 

2.3 

2.3

5.7 

7.8 

9.1 

4.6 

2.2 

2.2

23.6 

4.9 

1.9 

0.7 

0.2 

0.2

16.6

1.5 

3.4 

4.4 

3.1 

1.8 

2.3

2.1 

2.9 

4.3 

3.8 

1.6 

1.9

11.1 

3.0 

1.5 

0.6 

0.2 

0.3

2.1 

3.8 

4.3 

3.0 

1.5 

1.9

2.6 

3.6 

4.7 

2.8

1.3

1.4

11.9 

2.7 

1.4 

0.4

Q 

0.2

14.6

1.1 

2.2 

3.5 

3.0 

1.9 

2.9

1.1 

2.3 

3.8 

2.8 

2.1 

2.5

9.3 

2.5 

1.6 

0.7 

0.3 

0.3

1.6 

2.5 

3.6 

3.0 

1.5 

2.4

1.6 

3.0 

3.7 

2.6 

1.9 

1.8

10.0 

2.4 

1.2 

0.5 

0.2 

0.2

6.8

0.5 

1.1 

1.6

1.3 

0.9

1.4

0.7 

0.8 

1.9

1.2 

0.8

1.3

4.0 

1.3 

0.8 

0.4 

0.2 

0.1

0.7 

1.2 

1.5 

1.3 

0.9 

1.2

0.8 

1.3 

1.8 

1.1 

0.7 

1.1

4.3 

1.2 

0.8 

0.2 

0.2 

Q

3.5

0.3 

0.5 

0.7 

0.7 

0.4 

0.8

0.5 

0.7 

0.8 

0.6 

0.5 

0.5

1.9

0.9

0.2

0.2

Q

Q

0.3 

0.6 

0.7 

0.7 

0.4 

0.7

0.6 

0.8 

0.8 

0.5 

0.4 

0.4

2.1

0.8

0.2

0.1

Q

Q

3.17

11.81

6.82

6.07

7.46

10.28

9.64

9.29

6.97

5.76

7.53

9.50

10.23

3.63

8.05

10.87

16.29

25.07

27.40

9.39

6.79

6.29

7.84

11.49

11.00

7.98

6.54

5.85

8.48

10.81

11.16

3.45

8.34

11.36

19.89

27.82

32.69

See footnotes at end of table.

30

Energy Information Administration/Energy Consumption Series 

Residential Lighting: Use and Potential Savings
Table 4.7. Light Usage by Household Size,

Million U.S. Households, 1993 Continued

Housing Unit and Household 

Characteristics

RSE Column Factor:

Total

0.4

Household Size

1 

Person

0.9

2 

Persons

0.7

3 

Persons

1.0

4 

Persons

1.0

5

Persons

1.5

6or

More

Persons

2.2

RSE

Row

Factors

Fluorescent Lights Used 

1 to 4 Hours per Day

None ............................................ 75.5 19.6 23.8 12.9 11.0

1 ................................................... 16.1 3.4 5.9 2.8 2.6

2................................................... 3.8 0.5 1.5 0.8 0.6

3 or More ..................................... 1.2 Q 0.5 Q 0.4

4 to 12 Hours per Day

None ............................................ 75.1 19.6 24.1 12.7 10.7

1 ................................................... 15.9 3.1 5.6 2.8 2.9

2................................................... 4.3 0.7 1.5 0.8 0.7

3 or More ..................................... 1.4 Q 0.5 0.3 0.4

More than 12 Hours per Day 

None ............................................ 88.2 22.2 28.7 15.2 13.0

1 ................................................... 6.7 1.1 2.3 1.2 1.3

2................................................... 1.1 Q 0.5 Q 0.2

3 or More ..................................... 0.6 Q 0.2 Q Q

Compact Fluorescent Light 

Bulbs Used

Yes................................................. 8.6 1.4 3.4 1.6 1.3

No .................................................. 88.1 22.1 28.3 15.0 13.3

Halogen Light Bulbs Used

Yes................................................. 11.2 2.1 4.2 2.1 1.6

No .................................................. 85.4 21.4 27.5 14.5 13.0

Outdoor Lights

Yes (more than one

mayapply) ....................................... 63.5 12.0 21.0 11.8 11.1

Evening Only ................................. 25.9 3.3 8.1 5.2 5.6

All Night ......................................... 16.6 3.4 5.1 3.1 2.9

Automatic Control .......................... 18.2 3.1 6.9 3.4 3.2

High Intensity ................................. 3.2 0.5 1.1 0.6 0.5

All Wattage Less than 150............. 31.5 7.0 10.2 5.5 5.0

Gas Light1 ...................................... 0.5 Q 0.3 Q Q

No .................................................... 33.1 11.5 10.7 4.8 3.5

5.4

1.0 

0.2 

0.2

5.1 

1.2 

0.3 

0.1

6.0 

0.6 

Q 

Q

0.6 

6.2

0.9 

5.9

5.1 

2.5 

1.3 

1.1 

0.2 

2.6 

Q 

1.6

2.9

0.4

Q

Q

2.9 

0.4 

0.2 

Q

3.1 

0.3 

Q 

Q

0.3 

3.2

0.3 

3.1

2.5

1.3 

0.8 

0.5 

0.2 

1.2 

Q 

1.0

3.21

8.21

17.55

24.10

3.21

7.99

13.95

25.10

3.32

12.65

29.41

39.76

11.88

3.35

9.58

3.51

4.13

6.65

7.89

7.89

20.62

7.14

34.58

6.51

1 Gas includes LPG and natural gas.

Q = Data withheld either because the Relative Standard Error (RSE) was greater than 50 percent or fewer than 10 households were sampled.

Notes: • To obtain the RSE percentage for any table cell, multiply the corresponding column and row factors. • Because of rounding, data may not sum to totals. 

• See "Glossary" for definition of terms used in this report.

Source: Energy Information Administration, Office of Energy Markets and End Use, Forms EIA-457 A-C, E, and H of the 1993 Residential Energy Consumption Survey. 

(For specific titles of forms, see Appendix A.)

Energy Information Administration/Energy Consumption Series 

Residential Lighting: Use and Potential Savings 31
Table 4.8. Light Usage by Household Size, 

Percent of U.S. Households, 1993

Housing Unit and Household 

Characteristics

RSE Column Factor:

Total

0.5

1 

Person

1.0

Household Size

2

Persons

0.8

Persons

1.0

Persons

1.0

5 

Persons

1.4

6 or

More

Persons

2.0

RSE

Row

Factors

Total .................................................. 100.0 100.0 100.0

Indoor Electric Lights 

Total Number Lights 

1 to 4 Hours

None ............................................ 10.0 13.8 9.8

1 ................................................... 22.9 32.0 23.2

2................................................... 28.4 32.3 30.0

3................................................... 17.4 12.9 17.9

4................................................... 9.5 4.9 9.3

5 or More ..................................... 11.9 4.2 9.7

4 to 12 Hours

None ............................................ 13.9 21.6 12.7

1 ................................................... 21.6 30.8 22.0

2 ................................................... 27.4 28.1 28.2

3................................................... 17.3 11.0 18.3

4 ................................................... 9.5 5.1 9.4

5 or More ..................................... 10.4 3.3 9.6

More than 12 Hours per Day

None ............................................ 68.7 75.7 70.4

1 ................................................... 17.2 16.5 15.8

2................................................... 7.9 4.6 7.8

3................................................... 3.5 2.0 3.2

4................................................... 1.5 Q 1.7

5 or More ..................................... 1.2 Q 1.1

Incandescent Lights Used 

1 to 4 Hours per Day

None ............................................ 15.3 19.7 16.8

1 ................................................... 25.2 33.0 26.6

2................................................... 26.2 29.2 26.4

3................................................... 15.9 10.1 15.8

4................................................... 7.8 4.2 7.2

5 or More ..................................... 9.7 3.7 7.2

4 to 12 Hours per Day

None ............................................ 18.0 25.9 17.9

1 ................................................... 25.4 34.5 24.6

2................................................... 26.7 24.0 28.9

3................................................... 14.4 9.8 14.5

4................................................... 7.7 3.6 7.0

5 or More ..................................... 7.8 2.3 7.1

More than 12 Hours per Day

None ............................................ 72.9 78.5 74.6

1 ................................................... 16.3 15.7 15.5

2 ................................................... 6.6 3.5 6.1

3................................................... 2.5 1.5 2.3

4................................................... 1.0 Q 0.7

5 or More ..................................... 0.8 Q 0.7

100.0 100.0

8.8

20.7

26.8

18.9

11.1

13.7

12.6

17.4

26.0

22.6

9.9

11.5

66.8

18.3

8.9

3.4

1.0

1.6

12.8

23.2

25.8

18.1

8.8

11.3

15.8

22.0

28.5

17.1

8.1

8.5

71.5

16.0

8.2

2.4

Q 

1.1

7.2

15.1

24.3

20.6

13.0

19.8

7.6

15.5

26.3

19.3

14.1

17.2

63.4

17.2

11.0

4.8

1.8

1.8

11.2

17.2

24.3

20.4

10.2

16.7

11.0

20.3

25.6

17.9

13.0

12.3

68.4

16.7

8.5

3.8

1.4

1.1

100.0

7.5

15.6

23.9

18.5

13.8

20.8

9.7

12.4

28.2

17.9

12.3

19.5

58.9

19.2

11.6

5.8

3.0

1.5

10.1

18.3

22.4

19.1

13.1

17.1

12.1

18.5

26.3

16.3

10.2

16.5

64.2 

17.7 

11.2 

3.2 

2.6 

Q

100.0

8.0 

15.4

20.1

20.2

11.9

24.4

13.4

18.7

23.5

15.8

14.7

13.8

55.7

25.3 

6.9 

5.5

Q

Q

10.0

16.3

21.2

19.5

11.5

21.5

16.3

22.1

22.3

14.8

11.6

12.9

61.0 

24.3

6.2

3.7

Q

Q

0.0

11.39

6.49

5.64

6.89

9.93

9.02

8.94

6.55

5.18

6.98

9.07

9.79

2.61

7.52

10.84

16.09

24.80

26.98

8.90

6.54

5.70

7.41

11.17

10.47

7.60

6.10

5.31

7.90

10.54

10.67

2.35

7.97

11.19

19.81

27.33

31.81

See footnotes at end of table.

32

Energy Information Administration/Energy Consumption Series 

Residential Ughting: Use and Potential Savings
Table 4.8. Light Usage by Household Size,

Percent of U.S. Households, 1993 Continued

Housing Unit and Household 

Characteristics

RSE Column Factor:

Total

0.5

Household Size

1 

Person

1.0

2 

Persons

0.8

3 

Persons

1.0

4 

Persons

1.0

5 

Persons

1.4

6 or

More

Persons

2.0

RSE

Row

Factors

Fluorescent Lights Used 

1 to 4 Hours per Day

None ............................................ 78.2 83.1 75.0 78.0 75.7 79.2 83.1

1 ................................................... 16.6 14.5 18.5 16.8 17.5 15.4 12.5

2................................................... 3.9 2.3 4.9 4.6 4.4 3.1 Q

3 or More ..................................... 1.3 Q 1.7 Q 2.5 2.3 Q

4 to 12 Hours per Day

None ............................................ 77.7 83.5 75.9 76.5 73.1 75.5 83.7

1................................................... 16.4 13.0 17.6 16.7 19.6 17.9 11.2

2................................................... 4.4 3.0 4.8 5.1 4.9 4.9 4.5

3 or More ..................................... 1.5 Q 1.6 1.8 2.4 1.7 Q

More than 12 Hours per Day 

None ............................................ 91.3 94.4 90.6 91.6 89.1 89.1 89.1

1 ................................................... 6.9 4.7 7.2 7.0 8.9 8.5 7.5

2................................................... 1.1 Q 1.5 Q 1.4 Q Q

3 or More ..................................... 0.6 Q 0.7 Q Q Q Q

Compact Fluorescent Light 

Bulbs Used

Yes................................................. 8.9 6.1 10.7 9.5 9.1 8.2 7.5

No .................................................. 91.1 93.9 89.3 90.5 90.9 91.8 92.5

Halogen Light Bulbs Used

Yes................................................. 11.6 8.9 13.2 12.7 11.1 13.3 9.9

No .................................................. 88.4 91.1 86.8 87.3 88.9 86.7 90.1

Outdoor Lights

Yes (more than one

may apply) ....................................... 65.8 51.2 66.2 70.9 76.3 75.7 72.4

Evening Only ................................. 26.9 13.9 25.6 31.5 38.2 37.1 36.5

All Night ......................................... 17.2 14.7 16.1 18.5 19.6 19.7 21.7

Automatic Control .......................... 18.8 13.3 21.7 20.4 21.7 16.8 14.4

High Intensity ................................. 3.3 2.0 3.5 3.4 3.7 3.6 6.9

All Wattage Less than 150............. 32.6 29.9 32.3 33.0 34.2 37.7 33.5

Gas Light1 ...................................... 0.6 Q 0.9 Q Q Q Q

No .................................................... 34.2 48.8 33.8 29.1 23.7 24.3 27.6

1.83

7.76

16.93

23.72

1.74

7.54

13.79

24.83

1.23

12.37

28.44

38.05

11.54

1.15

9.34

1.32

2.80

5.80

7.32

7.21

20.26

6.46

33.04

6.16

1 Gas includes LPG and natural gas.

Q = Data withheld either because the Relative Standard Error (RSE) was greater than 50 percent or fewer than 10 households were sampled.

Notes: • To obtain the RSE percentage for any table cell, multiply the corresponding column and row factors. • Because of rounding, data may not sum to totals. 

• See "Glossary" for definition of terms used in this report.

Source: Energy Information Administration, Office of Energy Markets and End Use, Forms EIA-457 A-C, E, and H of the 1993 Residential Energy Consumption Survey. 

(For specific titles of forms, see Appendix A.)

Energy Information Administration/Energy Consumption Series 

Residential Lighting: Use and Potential Savings 33
Table 4.9. Mean Annual Electricity Consumption for Lighting, by Family Income 

by Number of Household Members, 1993

(Kilowatthours)

Family Income

RSE Column Factors:

All Households

Less than $10,000 .................................

$10,000 to $14,999 ................................

$15,000 to $19,999 ................................

$20,000 to $24,999 ................................

$25,000 to $34,999 ................................

$35,000 to $49,999 ................................

$50,000 to $74,999 ................................

All 

Households

0.6

Number of Household Members

One

1.4

Two

0.8

Three

1.2

Four

1.0

Five or 

More

1.3

940 604 923 1,023 1,198 1,265

668 557 657 793 952 943 

753 547 789 905 968 986 

888 695 831 865 1,227 1,321 

856 641 889 921 976 1,208 

962 630 1,000 1,015 1,095 1,247 

1,018 658 962 1,032 1,184 1,294 

1,130 646 982 1,127 1,345 1,403 

1,331 616 1,239 1,384 1,494 1,574

RSE 

Row 

Factors

2.02

5.35 

6.02 

5.89 

5.97 

4.64 

3.75 

4.24 

6.81

Notes: • To obtain the RSE percentage for any table cell, multiply the corresponding column and row factors. • Because of rounding, data may not 

sum to totals. • See "Glossary" for definition of terms used in this report.

Source: Energy Information Administration, Office of Energy Markets and End Use, Forms EIA-457 A-C, E, and H of the 1993 Residential Energy 

Consumption Survey. (For specific titles of forms, see Appendix A.)

Table 4.10. Mean Annual Electricity Consumption for Lighting, by Family Income 

by Number of Rooms, 1993

(Kilowatthours)

Family Income 

RSE Column Factors:

All Households ...................................

Less than $10,000 ..............................

$10,000 to $14,999 .............................

$15,000 to $19,999 .............................

$20,000 to $24,999 .............................

$25,000 to $34,999 .............................

$35,000 to $49,999 .............................

$50,000 to $74,999 .............................

$75,000 or More .................................

Total 

Households

0.5

Number of Rooms

One to 

Three

1.6

Four

1.1

Five

0.9

Six

0.9

Seven

1.1

Eight or 

More

1.2

940 497 690 875 1,003 1,181 1,420

668 452 610 728 852 1,012 1,149 

753 482 680 789 797 1,151 1,231 

888 521 732 885 1,047 1,066 1,410 

856 532 723 841 1,000 973 1,313 

962 581 713 972 945 1,196 1,390 

1,018 537 717 954 1,064 1,155 1,313 

1,130 471 700 901 1,109 1,291 1,421 

1,331 378 913 993 1,130 1,316 1,625

RSE 

Row 

Factors

2.08

6.04 

6.25 

6.16 

5.56 

4.92 

4.35 

4.62 

8.24

Notes: • To obtain the RSE percentage for any table cell, multiply the corresponding column and row factors. • Because of rounding, data may not sum to 

totals. • See "Glossary" (or definition of terms used in this report.

Source: Energy Information Administration, Office of Energy Markets and End Use, Forms EIA-457 A-C, E, and H of the 1993 Residential Energy Consumption Survey. (For specific titles of forms, see Appendix A.)

34

Energy Information Administration/Energy Consumption Series 

Residential Lighting: Use and Potential Savings
Table 4.11. Mean Annual Electricity Consumption for Lighting, by Number of 

Household Members by Number of Rooms, 1993

(Kilowatthours)

Number of Household 

Members

RSE Column Factors:

All Households ...................................

All 

Households

0.5

Number of Rooms

One to 

Three

2.0

Four

1.1

Five

0.9

Six

0.8

Seven

1.0

Eight or 

More

1.1

940 497 690 875 1,003 1,181 1,420

604 443 545 629 745 910 1,028 

923 580 705 884 968 1,141 1,264 

1,023 611 789 914 1,059 1,104 1,446 

1,198 544 854 1,066 1,113 1,365 1,522 

1,265 597 846 1,125 1,161 1,294 1,707

RSE 

Row 

Factors

2.08

4.76 

3.35 

4.40 

4.36 

5.10

Notes: • To obtain the RSE percentage for any table cell, multiply the corresponding column and row factors. • Because of founding, data may not sum to 

totals. • See 'Glossary' for definition of terms used in this report.

Source: Energy Information Administration, Office of Energy Markets and End Use, Forms EIA-457 A-C, E, and H of the 1993 Residential Energy 

Consumption Survey. (For specific titles of forms, see Appendix A.)

Table 4.12. Mean Annual Electricity Expenditures for Lighting, by Family Income 

by Number of Household Members, 1993

(Dollars)

Family Income

RSE Column Factors:

All Households ......................................

Less than $10,000 .................................

$10,000 to $14,999 ................................

$15,000 to $19,999 ................................

$20,000 to $24,999 ................................

$25,000 to $34,999 ................................

$35,000 to $49,999 ................................

$50,000 to $74,999 ................................

All 

Households

0.6

83

61

68

75

74

82

91

99

125

One

1.3

55

49

50

61

57

59

61

60

69

Number

Two

0.8

80

60

70

70

76

83

84

83

112

of Household rV

Three

1.1

92

71

82

73

87

87

95

101

131

Members

Four

1.0

106

90

88

108

75

94

104

119

137

Five or 

More

1.4

112

90

90

104

102

104

116

123

158

Hoc 

Row 

Factors

2.28

5.22

6.62

5.49

6.11

4.95

3.90

4.24

7.36

Notes: • To obtain the RSE percentage for any table cell, multiply the corresponding column and row factors. • Because of rounding, data may not 

sum to totals. • See "Glossary" for definition of terms used in this report.

Source: Energy Information Administration, Office of Energy Markets and End Use, Forms EIA-457 A-C, E, and H of the 1993 Residential Energy 

Consumption Survey. (For specific titles of forms, see Appendix A.)

Energy Information Administration/Energy Consumption Series 

Residential Lighting: Use and Potential Savings 35
Table 4.13. Mean Annual Electricity Expenditures for Lighting, by Family Income 

by Number of Rooms, 1993

(Dollars)

Family Income

RSE Column Factors:

All Households ...................................

Less than $10,000 ..............................

$10,000 to $14,999 .............................

$15,000 to $19,999 .............................

$20,000 to $24,999 .............................

$25,000 to $34,999 .............................

$35,000 to $49,999 .............................

$50,000 to $74,999 .............................

All 

Households

0.5

Number of Rooms

One to 

Three

1.6

Four

1.1

Five

0.9

Six

0.9

Seven

1.1

Eight or 

More

1.2

83 49 63 76 87 104 124

61 44 56 63 76 94 105 

68 46 62 70 75 94 109 

75 51 64 76 84 91 111 

74 53 65 72 84 80 111 

82 61 63 80 80 99 120 

91 53 68 87 93 99 116 

99 51 71 80 98 113 120 

125 43 101 95 99 130 149

RSE 

Row 

Factors

2.34

6.09 

6.92 

6.43 

6.06 

5.00 

4.61 

4.68 

8.25

Notes: • To obtain the RSE percentage for any table cell, multiply the corresponding column and row factors. • Because of founding, data may not sum to 

totals. • See "Glossary" for definition of terms used in this report.

Source: Energy Information Administration, Office of Energy Markets and End Use, Forms EIA-457 A-C, E, and H of the 1993 Residential Energy 

Consumption Survey. (For specific titles of forms, see Appendix A.)

Table 4.14. Mean Annual Electricity Expenditures for Lighting, by Number of 

Household Members by Number of Rooms, 1993

(Dollars)

Number of Household 

Members

RSE Column Factors:

All Households ...................................

All 

Households

0.5

Number of Rooms

One to 

Three

1.8

Four

1.1

Five

0.9

Six

0.9

Seven

1.0

Eight or 

More

1.2

83 49 63 76 87 104 124

55 44 51 54 69 78 87 

80 56 63 77 82 96 107 

92 60 73 82 95 97 131 

106 64 78 93 96 124 134 

112 70 83 98 99 117 150

RSE 

Row 

Factors

2.34

5.33 

3.38 

4.75 

4.53 

5.89

Notes: > To obtain the RSE percentage for any table cell, multiply the corresponding column and row factors. • Because of founding, data may not sum to 

totals. • See "Glossary" for definition of terms used in this report.

Source: Energy Information Administration, Office of Energy Markets and End Use, Forms EIA-457 A-C, E, and H of the 1993 Residential Energy 

Consumption Survey. (For specific titles of forms, see Appendix A.)

36

Energy Information Administration/Energy Consumption Series 

Residential Lighting: Use and Potential Savings
Table 4.15 Total Annual Electricity Expenditures for Lighting, by Family Income, 

Million U.S. Households, 1993

Electricity 

Expenditures 

(Dollars)

RSE Column Factors:

All Households ...............................

26 to 50 ..........................................

51 to 75 ..........................................

76(0100 ........................................

101 to 125 ......................................

126to150 ......................................

More than 150 ................................

Total

0.4

Family Income

Less 

than 

$10,000

1.1

$10,000 

to 

$14,999

1.1

$15,000 

to 

$19,999

1.3

$20,000 

to 

$24,999

1.3

$25,000 

to 

$34,999

1.0

$35,000 

to 

$49,999

0.9

$50,000 

to 

74,999

1.0

$75,000 

or 

More

1.3

96.6 14.6 11.1 9.6 8.7 14.1 17.5 12.6 8.3

9.2 3.0 1.8 0.9 0.9 1.0 0.9 0.4 0.1 

21.0 4.4 3.2 2.4 2.2 3.3 2.8 1.8 0.8 

21.7 2.9 2.4 2.5 2.2 3.2 4.3 2.8 1.4 

16.1 2.0 1.6 1.6 1.4 2.5 3.5 2.2 1.2 

11.1 1.0 0.8 1.0 0.9 1.6 2.2 2.2 1.4 

6.8 0.5 0.6 0.4 0.6 0.9 1.4 1.4 0.9 

10.8 0.7 0.6 0.8 0.6 1.4 2.3 1.9 2.5

RSE 

Row 

Factors

3.68

12.40 

8.20 

7.53 

8.98 

11.02 

13.75 

12.69

Notes: • To obtain the RSE percentage for any table cell, multiply the corresponding column and row factors. • Because of founding, data may not sum to 

totals. • See "Glossary" for definition of terms used In this report.

Source: Energy Information Administration, Office of Energy Markets and End Use, Forms EIA-457 A-C, E, and H of the 1993 Residential Energy Consumption 

Survey. (For specific titles of forms, see Appendix A.)

Table 4.16. Total Annual Electricity Expenditures for Lighting, by Number of Rooms, 

Million U.S. Households, 1993

Electricity 

Expenditures 

(Dollars)

RSE Column Factors:

All Households ...................................

25 or LGSS

26 to SO ...............................................

511075...............................................

76 to 100 .............................................

101 to 125 ...........................................

126 to 150 ...........................................

More than 150 ....................................

Total

0.4

Number of Rooms

One to 

Three

1.7

Four

1.1

Five

0.9

Six

1.0

Seven

1.2

Eight or 

More

1.3

96.6 11.4 17.9 21.3 19.5 12.8 13.8

9.2 3.2 2.6 1.9 1.0 0.3 0.2 

21.0 3.9 5.6 5.1 3.6 1.7 1.1 

21.7 2.1 4.5 5.4 4.9 2.5 2.3 

16.1 1.1 2.4 3.8 3.8 2.6 2.4 

11.1 0.5 1.3 2.4 2.5 2.2 2.1 

6.8 0.2 0.7 1.1 1.7 1.3 1.8 

10.8 0.3 0.8 1.6 2.0 2.2 4.0

RSE 

Row 

Factors

3.41

12.40 

7.40 

6.23 

7.39 

9.55 

12.25 

11.94

Notes: • To obtain the RSE percentage for any table cell, multiply the corresponding column and row factors. • Because ol Founding, data may not sum to 

totals. • See "Glossary" lor definition of terms used in this report.

Source: Energy Information Administration, Office of Energy Markets and End Use, Forms EIA-457 A-C, E, and H of the 1993 Residential Energy 

Consumption Survey. (For specific titles of forms, see Appendix A.)

Energy Information Administration/Energy Consumption Series 

Residential Lighting: Use and Potential Savings 37
Table 4.17. Total Annual Electricity Expenditures for Lighting, by Number of Household Members, 

Million U.S. Households, 1993

Electricity 

Expenditures 

(Dollars)

RSE Column Factors:

All Households ...................................

26 to 50 ...............................................

51 to 75 ...............................................

76 to 100 .............................................

101 to 125 ...........................................

126 to 150 ...........................................

More than 150 ....................................

Total

0.5

96.6

9.2

21.0

21.7

16.1

11.1

6.8

10.8

One

1.1

oq R

5.7

7.8

4.7

2.4

1.3

0.6

0.9

Numbe

Two

0.6

31.7

2.5

7.5

7.8

5.1

3.7

2.2

2.9

r of Household Vfc

Three

1.2

16.6

0.5

3.1

4.0

3.2

2.4

1.4

1.9

imbers

Four

1.3

14.6

0.2

1.5

3.3

3.2

2.1

1.4

2.8

Five or 

More

1.4

10.2

0.2

1.1

2.0

2.1

1.5

1.1

2.3

RSE 

Row 

Factors

2.56

13.05

6.34

5.30

6.57

8.06

10.88

9.84

Notes: • To obtain the RSE percentage for any table cell, multiply the corresponding column and row factors. • Because of rounding, data may not sum to totals. 

• See "Glossary" for definition of terms used in this report.

Source: Energy Information Administration, Office of Energy Markets and End Use, Forms EIA-457 A-C, E, and H of the 1993 Residential Energy Consumption 

Survey. (For specific titles of forms, see Appendix A.)

38

Energy Information Administration/Energy Consumption Series 

Residential Lighting: Use and Potential Savings
Table 4.1 8. Number of

Hours Used

Total .........

Unknown .... 

Less than One 

1 to 1 .9 .....

2 to 3.9 ......

4 to 7.9 ......

8 to 11.9 .....

12 or More . . .

Total

4,196 

104 

1,106 

994 

1,003 

739 

109 

141

Lights b

Bath 

room

621 

6 

179 

225 

145 

46 

11 

9

/ Room by Hours Used, 1993

Bed- Din 

room Ro

1,121 

19 

359 

306 

297 

121 

10 

9

Den 

mg Family/ 

3m Rec Room

218 279 

10 12 

59 61 

61 32 

57 69 

25 81 

3 11 

3 13

Hallway/ 

Stairs

193 

3 

92 

46 

24 

12 

5 

11

Kitchen

820 

21 

126 

154 

215 

202 

36 

66

Living 

Room

711 

21 

125 

112 

160 

240 

29 

24

Laundry 

Room/ 

Other

233 

12 

105 

58 

36 

12 

4 

6

Note: These data represent the 474 households included in the Lighting Supplement. The supplement was not designed to weight the 

data to the population level.

Source: Energy Information Administration, Office of Energy Markets and End Use, Forms EIA-457A-C, E, and H of the 1993 Residential 

Energy Consumption Survey.

Table 4.19. Number of Lights by Type of Bulb by Hours Used, 1993

Bulb Type

Hours Used Total

Low

Total.............. 4,196 431

Unknown ......... 1 04 11

LessthanOne ..... 1,106 162

1 to 1.9 ........... 994 105

2 to 3.9 ........... 1 ,003 58

4 to 7.9 ........... 739 52

8to11.9 .......... 109 9

12 or More ........ 141 34

Incandescent

Medium High Unknown Shor

Fluorescent Other

t Long Compact Halogen

2,811 409 14 159 173 34 24 

58 19 012 0 0 

746 92 3 31 26 2 4 

710 80 3 36 27 5 4 

705 113 3 30 49 11 5 

474 81 3 36 43 12 11 

64 17 089 1 0 

54 7 2 17 17 3 0

Other/ 

Unknown

141 

13 

40 

24 

29 

27 

1 

7

Note: These data represent the 474 households included in the Lighting Supplement. The supplement was not designed to weight the 

data to the population level.

Source: Energy Information Administration, Office of Energy Markets and End Use, Forms EIA-457A-C, E, and H of the 1993 Residential 

Energy Consumption Survey.

Energy Information Administration / Energy Consumption Series 

Residential Lighting: Use and Potential Savings 39
Table 4.20. Number of Lights by Bulb Type by Room, 1993

Room

Total ...................

Bathroom ..............

Den/Family/ Rec Room . . . 

Hallway/Stairs ..........

Kitchen ................

Laundry Room/Other .....

Total

Bulb Type

Incandescent F

Low Medium High Unknown Short

4,196 431 2,811 409 14 159 

621 44 417 81 4 35 

1,121 119 868 66 6 8 

218 28 119 51 2 0 

279 28 171 42 1 7 

193 42 136 6 01 

820 80 440 70 1 85 

711 65 511 80 0 11 

233 25 149 13 0 12

uorescent Other

Other/ 

Long Compact Halogen unknown

173 34 24 141 

14 2 1 23 

5 9 8 32 

1 1 2 14 

12 2 3 13 

3005 

104 12 1 27 

8 8 8 20 

26 0 1 7

Note: These data represent the 474 households included in the Lighting Supplement. The supplement was not designed to weight the 

data to the population level.

Source: Energy Information Administration, Office of Energy Markets and End Use, Forms EIA-457A-C, E, and H of the 1993 Residential 

Energy Consumption Survey.

Table 4.21. Number of Households by Daily Kilowatthours by Number of Rooms

Number of Kilowatthours

All Households ............

One or Less ..............

One to Two ...............

Two to Three .............

Three to Four .............

More than Four ...........

Total

474

117

153

89

58

57

Number of Rooms

One to Four Five Rooms Six Rooms 

Rooms

145 96 113

58 27 15

51 30 42

19 20 23

11 9 20

6 10 13

Seven or More 

Rooms

120

17

30

27

18

28

Note: These data represent the 474 households included in the Lighting Supplement. The supplement was not designed to 

weight the data to the population level.

Source: Energy Information Administration, Office of Energy Markets and End Use, Forms EIA-457A-C, E and H of the 1993 Residential 

Energy Consumption Survey.

Table 4.22. Number of Households by Daily Kilowatthours by Number of Household Members

Number of Kilowatthours Total

Number of Household Members

One Two Three Four or More

All Households .

One or Less . . . 

One to Two .... 

Two to Three .. 

Three to Four . . 

More than Four

474

117

153

89

58

57

117

51

44

11

5

6

149

35

46

38

17

13

83

17

25

19

11

11

125

14

38

21

25

27

Note: These data represent the 474 households included in the Lighting Supplement. The supplement was not designed to 

weight the data to the population level.

Source: Energy Information Administration, Office of Energy Markets and End Use, Forms EIA-457A-C, E and H of the 1993 Residential 

Energy Consumption Survey.

40

Energy Information Administration / Energy Consumption Series 

Residential Lighting: Use and Potential Savings
Table 4.23. Number of Households by Daily Kilowatthours by Family Income 

(Dollars)

Number of Kilowatthours

All Households ...........

One or Less .............

One to Two ..............

Two to Three ............

Three to Four ............

More than Four ..........

Total

474

117

153

89

58

57

Family Income

Less than 1 0,000 to 20,000 to 

10,000 19,999 34,999

69 113 110

25 36 37

97 *3Q T^

11 19 19

3 11 10

389

35,000 to 50,000 

49,999 or More

88 94

8 11

27 25

22 18

18 16

13 24

Note: These data represent the 474 households included In the Lighting Supplement. The supplement was not designed to weight 

the data to the population level.

Source: Energy Information Administration, Office of Energy Markets and End Use, Forms EIA-457A-C, E and H of the 1993 Residential 

Energy Consumption Survey.

Energy Information Administration / Energy Consumption Series 

Residential Lighting: Use and Potential Savings 41

Appendix A

Survey Forms

This appendix contains lighting questions from the 1993 RECS Household Questionnaire as well as a complete copy of 

the Lighting Supplement Questionnaire. Table Al presents a brief summary of the questions included in each of the 

questionnaires. A complete list of all forms used in the 1993 Residential Energy Consumption Survey follows. 

Household Energy Consumption and Expenditures, 1993 contains a copy of each form.

• EIA-457A Household Questionnaire (lighting questions only)

• EIA-457B Household Mail Questionnaire (not included)

• EIA-457C Rental Agent Form (not included)

• EIA-457D Liquefied Petroleum Gas Usage (not included)

• EIA-457E Electricity Usage (not included)

• EIA-457F Utility Gas Usage (not included)

• EIA-457G Fuel Oil or Kerosene Usage (not included)

• EIA-457H Lighting Supplement

Energy Information Administration / Energy Consumption Series 

Residential Lighting: Use and Potential Savings 43
Table A1. Lighting Information Collected by the Household Questionnaire and Lighting 

Supplement ________

Indoor Lights

Household Questionnaire (7,111 households)

Number of Lights on: 

1 to 4 hours 

4 to 12 hours 

12 or more hours

How Many of Above are Fluorescent 

Lighting Supplement (474 households)

Number of Lights on: Type and Wattage:

15 minutes or more incandescent

1-2 hours low (10-40 watts)

2-4 hours medium (41-149 watts) 

4-8 hours high (150 watts or more) 

8-12 hours 

12 or more hours Fluorescent

short (< 24 inches)

Room long (24 inches or more) 

Kitchen, Living Room, etc. compact

Halogen

Outdoor Lights 

Household Questionnaire

Does Household Use Outdoor Lights

Use: Type:

Evening Electric

All night Gas

Timer/Motion Detector High Intensity Discharge

Total Wattage Less than 150 Watts

Lighting Supplement

No Information Collected

Source: Energy Information Administration, Office of Energy Markets and End Use, Forms EIA-457A and H of the 1993 

Residential Energy Consumption Survey.

Energy Information Administration / Energy Consumption Series 

44 Residential Lighting: Use and Potential Savings
Lighting-Related Questions from the RECS Household Questionnaire

INDOOR LIGHTS

F-1. Please turn to Exhibit F-1. Thinking of a typical November weekday, please tell me the number of 

indoor lights your household has turned on for each of the following time periods.

a. More than 12 hours per day ...............

b. Between 4 hours and 12 hours per day .......

c. Between 1 hour and 4 hours per day .........

F-1. NUMBER OF 

LIGHTS

NONE ......... 00

NONE ......... 00

NONE ......... 00

F-2. NUMBER OF 

FLUORESCENT 

LIGHTS

NONE ......... 00

NONE ......... 00

NONE ......... 00

293-96

297-300

307-04

FOR EACH ANSWER OF 1 LIGHT OR MORE IN "a" THROUGH "c" 

IN F-1 ABOVE, ASK F-2:

F-2. Of the (NUMBER) indoor lights on (HOURS), how many 

are fluorescent? ———————————————————

Energy Information Administration / Energy Consumption Series 

Residential Lighting: Use and Potential Savings 45
Lighting-Related Questions from the RECS Household Questionnaire 

(Continued)

OUTDOOR LIGHTS

F-3. Please turn to Exhibit F-3. Thinking about a typical November weekday, please indicate a!i the 

statements that describe the outdoor lights used by your household.

YES NQ 

a. NO OUTDOOR LIGHTS OR RARELY USED ................ 1 0 305

b. OUTDOOR LIGHTS TURNED ON DURING THE EVENING, BUT

TURNED OFF BEFORE BEDTIME ....................... 1 0 306

c. OUTDOOR LIGHTS LEFT ON ALL NIGHT ................. 1 0 307

d. OUTDOOR LIGHTS WITH A TIMER, MOTION SENSOR, OR

PHOTOSENSOR ...................................... 1 0 308

e. OUTDOOR GAS LIGHT ................................ 1 0 309

i. HIGH INTENSITY DISCHARGE (HID) OUTDOOR LIGHTS, 

SUCH AS METAL HALIDE OR HIGH PRESSURE SODIUM 

LIGHTS ............................................. 1 0 31°

g. TOTAL WATTAGE OF ALL OUTDOOR LIGHTS IS LESS THAN

150 WATTS .......................................... 1 0 311

h. DON'T KNOW ........................................ 1 0 312

Energy Information Administration / Energy Consumption Series 

46 Residential Lighting: Use and Potential Savings
1993 RESIDENTIAL ENERGY CONSUMPTION SURVEY 1-4

HOUSEHOLD LIGHTING USAGE SUPPLEMENT

Energy Information Administration / Energy Consumption Series 

Residential Lighting: Use and Potential Savings 47
LS-1. Think of a typical 24-hour November weekday. For each indoor light used in your home for at 

least 15 minutes, please identify the light, how long that light is on, and what type of bulb is 

in the light. As we list each room, keep in mind all activities and times-of-day that the light is 

used.

21-26 

27-32 

33-38 

39-44 

45-50 

51-56 

57-62 

63-68 

69-74 

75-80 

81-86 

87-92 

93-98 

99-104 

105-110

COLUMN A

LS-2. Describe the 

(FIRST/NEXT) light in your 

home's (ROOM).

ENTER ROOM CODES FROM BOX 

ABOVE

COLUMN B

LS-3. Approximately how 

many hours is this light 

used in a typical 24-hour 

November weekday?

ENTER "LESS THAN 1 HR" OR 

NUMBER OF HOURS OR 

CIRCLE DK FOR DON'T KNOW

: ; • . :.,•.,::•:., ,• : ; : ,• : ; :: : : , . ,:.. ••.;. -/^ :• p: -''Q|^

DK

^M^ydiH^^.i-^mmbM

DK

; : l " : ' I "•"•'•*"! ; ; '; i; • '"• '; . ; ; ; .'• ' '- [:^-'i\if^

. . ; . ...::.: • . • :•:•-: ...-.;.- Ut\~-:-:~ff

DK

^ J*'^Rn!; 5; : : ;:' •"-';.'- ;:bfd

DK

::'.•.•:.;..:: ; : :.• : . : '• .': . 'DK;L!

DK

l^^'^^il^'^^^li:^-^^!

DK

mKmmS-im^^symlDK

H }:l!li?' rftStm IM ^^mftl.

COLUMN C

LS-4. IF DK IN COLUMN B: 

Please turn to Exhibit LS-4. 

Which range best describes 

this light's usage in a typical 

24-hour period?

15 

mins 

-1 hr

•aom

01

iiitr

01

01

•l-M-l:

01

.Mfltcr:

01

IJcWE

01

fiillS

01

S01H:=

1-2

:i;02i

02

•loil

02

lt)i: 02

ii:

02

1D2L

02

mm

02

161:

02

i.om

2-4

s03l'

03

H:

03

loil

03

Ibi

03

i:03l: 03

!fi3^:

03

in

03

fOSK

4-8

sola

04

111

04

ffli?

04

11

04

.1.04s

04

Mil

04

liil

04

P011

8-12

mm

05

tblS

05

lili

05

loll

05

P05«;.:

05

loll

05

losi

05

&m

12+

IsQIl

06

06

IB;

06

111

06

S06f:

06

till

06

loll

06

DK

91

96

96

96

96

96

OR9v

96

96

96

m

96

Hi

96

i|j^::^ afo

48

Energy Information Administration / Energy Consumption Series 

Residential Lighting: Use and Potential Savings
HALOGEN = HALOGEN LIGHT

^ ' '"TM"""° """"iiiif i

COLUMN D

LS-5. Please turn to Exhibit LS-5. Please indicate the type of bulb(s) used in this light. 

TYPE OF BULB

(CIRCLE APPROPRIATE BULB TYPE)

INCANDESCENT 

(STANDARD)

LOW

K»!B

01

1111

01

lit!

01

IIP

01

ilbli

01

01

i '%m

01

iiiti

MED

fiom

02

02

Moil!

02

t!6¥ti

02

Moll

02

02

IJ02:<i>

02

loll

HIGH

Kmm.

03

'< .< '•;:. jm^'A-A !:;'. :!:.:IU3i*"p:

03

H;i01i;:H3

03

l^t^t-l

03

ffibiifl

03

iiTOr;!

03

mmm

03

iiiii

DK

WK

04

111

04

IbT

04

ib*l

04

loll

04

aQ4y

04 'mm

04

loll

FLUORESCENT

SHORT

p.^j&Hfi

05

|!: K|fisHII:

05

!i;.;M?u^

05

|rt!iifl:]f

05

ftfvfeiitE

05

r.rr;:ii|.|: ?y

05

Kl i : !'.i05;:;: :jA::t

05

:^. : .-: ' ? ''. •$****<?•? i- 11 -:'":

;•.•;•. ;:';: :;;D5i:::: ! :^i::::: !

LONG

SSJUfSS

06

06

|s;lO'6l-;f

06

It-SKJI

06

tililll

06

|<: ld: i'il.

06

06

lioill

COMPACT

IBIIIO'JICBS

07

lllii^lififi

07

•ii ' 'i i.i.: .'.!; li^lj^pllil: Ff ji

07

tiifSj^lffSt

07

IBItfl^-liiftfl

-•-• '• . =. v W: /.:: J . : : : :..•:

07

l:iSlll011:!lli

07

Mi;!'?i;llli!iif

07

ll-B.Ii.0^:s:|.f :Ffc

DK

llil

08

:

08

ill

08

liiJii!

08

lilii

08

lilii

08

fl«8«

08

•^•lf&&^ 

?-£&&&%

HALOGEN

IB

09

S i slliif f ffi

09

I:'! :S::*||t;.'';J'i;::!

:;:-:: -S:-: i::::::::::: V»? > •: ••: : '':;:W:! !'!:

09

r i vRisOSl! t.ill

09

i.a l^ii*!':;;,!!!

09

illJIillf!

09

09

ilS^lliiiit

OTHER 

(CHECK BOX)

iWSliM!filM|ttT3

10 D

IB^.|l;?:*lSf'n?'-;s-tl

10 D

mi]i\>:imMm^ : i

10 n

IwlS^.Iti Sh: .?: ,U :;•;'! 5: 1

10 D

i:i8l:':: i^vM.;;: i|i::: ;'." '>.!H';|i

10 n

:SSiffI1Sf:|||||:f: ; " -U':,!;''*

10 n

•^'ft^-':' ^ '• i ': ":--^'f!'f--&^-'---.'-^''': ".: :"f" iV i': 

•.'lUi^S'v;;.1 "i :.:.; |.: ^liitt: |IO:. .!• • ;.' ••' i 1 '^?; :';::!

10 n

iSi'ili I-:::?: f'-::V'J 1^*.'^ .?-': : t" -i '":' x: ! f. :.4 f

J-«:i:'::;: :;;;;;:.:;:;::;. ji^j-hS •; ••; :•;;•!;; :":!•;

DK 

BULB 

TYPE

S^."i" :fitjj£ :- : ; : ^

96

S:Pf'l

96

l!:p:iiil

96

iiHIH

96

Sllifi

96

iRsiiii; i

96

mm^i

96

;v: -;: :iS6f'':;i .r ?

111-112 

113-114 

115-116 

117-118 

119-120 

121-122 

123-124 

125-126 

127-128 

129-130 

131-132 

133-134 

135-136 

137-138 

139-140

CONTINUE TO LS-6 ON BACK OF THIS FORM.

Energy Information Administration / Energy Consumption Series 

Residential Lighting: Use and Potential Savings 49
LS-6. How many more indoor lights does your home use for 15 minutes or more in a typical 24-hour 

November weekday?

NUMBER: 769-70

INTERVIEWER: RETURN TO SECTION O. HOUSING MEASUREMENTS ON PAGE 98.

50 Energy Information Administration / Energy Consumption Series 

Residential Lighting: Use and Potential Savings
Exhibit F-1

General Instructions For Counting Lights 

Count any and all lights In home

A light is defined as every light bulb turned on By a single light switch

A fixture or lamp with two switches is counted as two lights

Examples:

If light has more than one bulb and more than one switchTcount as / two lights. Example: Floor Lamp.

t)

If light has only one switch, count as one light even if it has more than one bulb. Example: Chandelier

If light can be turned on by a single switch, count it as one light. Example: Track Lighting

Energy Information Administration / Energy Consumption Series 

Residential Lighting: Use and Potential Savings 51
Exhibit F-3

Outdoor Lights

• No Outdoor Lights or Rarely Used

• Outdoor Lights Turned On During the 

Evening, but Turned Off Before Bedtime

• Outdoor Lights Left on All Night

• Outdoor Lights with a Timer, Motion 

Sensor, or Photosensor

Outdoor Gas Light

High Intensity Discharge (HID) Outdoor 

Lights (Such as metal halide or high pressure 

sodium lights)

Total Wattage of Outdoor lights is less 

Than 150 Watts

Energy Information Administration / Energy Consumption Swl*a 

52 Residential Lighting: UM and Potential Savings
Appendix B

End-Use Estimation Methodology

Two Approaches

Two approaches for estimating the kilowatthours used for lighting that are based upon data from the 1993 RECS were 

used in this report. The first approach used only bulb type and hours of usage data from the RECS Lighting Supplement. 

The second approach is a regression-based approach that uses the full RECS dataset. This appendix will provide more 

details concerning both of these methods.

The main purpose of the Lighting Supplement, which collected data from a subsample of the 1993 RECS respondents, 

was to develop a model of kilowatthours used for lighting as a function of variables obtained on the full RECS Household 

Questionnaire. The resulting model was used to create an index of lighting usage. This index was then used as a 

predictor variable in a regression analysis. The results of the regression analysis were used to disaggregate the total 

electricity usage into consumption by end use. One of these end uses is lighting.

Using Lighting Supplement Data

The RECS Lighting Supplement (Form EIA-457H) is a short questionnaire completed by 474 of the 7,111 households 

that responded to the RECS Household Questionnaire (Form EIA-457A). The Lighting Supplement was not 

administered to all of the 1993 RECS respondents because of cost and respondent burden constraints. The Lighting 

Supplement provides detailed information on indoor lights used 15 minutes or more (up to a maximum of 15 lights) by 

type of bulb, hours used, and the room in which the light is located. If the respondents reported that there were more 

than 15 lights that met the criteria covered by the Lighting Supplement, only the number of additional bulbs was 

recorded.

Calculating Kilowatthours

Lights in the Lighting Supplement database were assigned a wattage amount based upon the bulb type reported. 

Similarly, the hours used for a light were inferred from the respondent's estimate of the number of hours the light was 

used.

Kilowatthours = Wattage * Hours Used

1,000

The kilowatthours for each light equals the wattage times the hours, divided by 1,000. The kilowatthours for each 

respondent to the Lighting Supplement equal the sum of the estimated kilowatthours for all the lights for that respondent.

Assigning Wattage to Lights

Respondents categorized lights by type, such as incandescent, fluorescent, halogen, or other. The specific wattage was 

assigned to each type by using the values in Table B.I.

Wattage for Incandescent Lights

Incandescent lights in the Lighting Supplement database were assigned a wattage based upon the respondents' estimates 

of their wattage. Lighting fixtures with more than one bulb were counted as one light. The wattage for these fixtures 

was the total wattage of all bulbs in the fixture. The respondents were asked to categorize incandescent lights by their 

total wattage. Lights with total wattage less than 10 (night lights) were excluded from the Lighting Supplement. 

Incandescent lights with a total between 10 and 40 were coded as "low" incandescent. Those with wattage between 41 

and 149 were coded as "medium" incandescent and those with 150 or more were coded as "high" incandescent. It is

Energy Information Administration / Energy Consumption Series

Residential Lighting: Use and Potential Savings 53
assumed that some of the lights coded as "medium" incandescent are actually fixtures with multiple bulbs. The same 

applies to "high" incandescent. Incandescent lights coded as "low" were assigned a wattage of 30, "medium" were 

assigned a wattage of 100, and "high" were assigned a wattage of 200. Incandescent lights for which the respondent did 

not provide a wattage estimate were assigned a wattage of 60.

Table B.1 Bulb Type and Wattage__________

________Bulb Type_______| Assigned Wattage 

Incandescent

Low .......................... 30

Medium ...................... 100

High ......................... 200

Unknown ..................... 60

Fluorescent

Short......................... 17

Long ......................... 40

Compact...................... 13

Unknown ..................... 40

Halogen ....................... 250

Other ......................... 60

Don't Know, No Answer ......... 60

Lights Beyond 15 Listed .........______________60

Source: Energy Information Administration, Office of Energy Markets and End Use, 1993 Residential 

Energy Consumption Survey.

Note: Wattage assignments for fluorescent lights are based on data from various lighting industry 

literature. Incandescent wattages are based on the Lighting Supplement Questionnaire.

Wattage for Fluorescent Lights

Fluorescent lights in the Lighting Supplement data base were assigned a wattage based upon the respondents' description 

of the lights. Lights categorized as "short" fluorescent were assigned a wattage of 17, "Long" fluorescent lights were 

assigned a wattage of 40, and "compact" fluorescent lights were assigned a wattage of 13. Fluorescent lights for which 

the type was coded as "unknown" were assumed to be long fluorescent and were assigned a wattage of 40.

Wattage for Halogen Lights

The Lighting Supplement did not distinguish between the different types of halogen lights. Halogen desk lights may have 

a low wattage (10 to 20), while halogen floor lights may have a high wattage (200 to 500). Only 24 out of the 4,196 

lights in the Lighting Supplement data base are Halogen lights. All halogen lights were assigned a wattage of 250 as a 

compromise.

Wattage for Other Bulb Types

Lights in the Lighting Supplement data base that were not classified as incandescent, fluorescent, or halogen were 

assigned a wattage of 60. This category includes lights where the respondent classified the lights as "other," where the 

respondent did not know the type, and lights where no type was recorded because the limit of 15 lights for a respondent 

had been reached.

Energy Information Administration / Energy Consumption Series 

54 Residential Lighting: Use and Potential Savings
Assigning Hours of Usage

For each light listed in the Lighting Supplement, the respondents were asked:

"Think of a typical 24-hour November weekday. For each indoor light used in your home for at least 15 minutes, 

please identify the light, how long that light is on, and what type of bulb is in the light fixture. As we list each room, 

keep in mind all activities and times-of-day that the light is used."

The responses were either the number of hours, a category for the number of hours, or "don't know." If the respondent 

reported the number of hours, then the light was assigned the reported number of hours. If a category for the number 

of hours was given, but not the actual number, the light was assigned the midpoint of the category. The only exception 

was the lowest category (15 minutes to 1 hour). In this case, the light was assigned the value of .5. If the respondent 

did not give either an estimate of the number of hours or a category, the lights were assigned a value of 1 hour. Similarly, 

lights beyond the 15 listed were given a value of 1 hour.

Modeling Kilowatthours by Using Lighting Supplement Data

The regression analysis of the Lighting Supplement data was done in two steps. In both steps, a stepwise linear 

regression program was used and the dependent variable was the kilowatthour estimate for lighting obtained from the 

bulb type and hours data described above. In addition, both steps used the same set of independent variables. In the first 

step, all of the observations received the same weight. In the second step, the Lighting Supplement observations were 

given a weight equal to the inverse of the predicted kilowatthours obtained from the first step. This weighting was used 

to adjust for the higher variance of the error term for households that were projected to use more electricity for lighting.

The set of independent variables used in both regression steps were obtained from the full 1993 RECS data set. The 

variables used are as follows:

Full RECS lighting variables

XI: Number of lights on more than 12 hours

X2: Number of lights on between 4 and 12 hours

X3: Number of lights on between 1 and 4 hours

X4: Number of fluorescent lights on more than 12 hours

X5: Number of fluorescent lights on between 4 and 12 hours

X6: Number of fluorescent lights on between 1 and 4 hours

Functions of full RECS lighting variables

X7-X12: The square root of the above variables

X13: An indicator variable that equals 1 if at least one light was on more than 12 hours

Full RECS variables on the size of the dwelling 

X14: Number of rooms

X15: Total square footage of housing units (heated and unheated) 

X16: Heated square footage 

X17: Number of Windows

Full RECS variables on number of household members

X18: Number of household members

X19: Square root of the number of household members

X20: Number of household members aged 13 to 65

X21: Square root of the number of household members aged 13 to 65

X22: Number of household members aged 6 to 65

X23: Square root of the number of household members aged 6 to 65

Type of housing unit

X24: Single-Family attached unit

X25: Mobile Home

X26: Apartment units in a building with 2 to 4 units

Energy Information Administration / Energy Consumption Series

Residential Lighting: Use and Potential Savings 55
X27: Apartment units in a building with 5 or more units

Family-Income Level

X28: low (less than $20,000) 

X29: Medium ($75,000 - $99,999) 

X30: High ($100,000+)

Age of householder

X31: 75 or more 

X32: 70 or more 

X33: 65 or more 

X34: 34 or less

Daytime use of home

X35: Operation of a home-based service or business 

X36: Other activity requiring a lot of energy 

X37: Someone home all day

Results

The second step produced the following model: 

Ki]owatthours= -90.7

115.4

44.3

282.2

0.0491

184.7

X

X

X

X

X

X2

X3

X4

X15

X19

Using Full RECS Data 

Introduction

For each household that responded to the 1993 RECS, the annual amount of electricity used for five end-use categoriesspace heating, water heating, air-conditioning, refrigerators, and general appliance usage-was estimated. The end-use 

amounts were not based on data produced by placing meters on individual appliances; rather, they were obtained by 

estimating how much of the total annual consumption for electricity can be attributed to each of the end-use categories 

for each household by using a regression technique. The data from the Lighting Supplement allowed us to estimate 

lighting as a subcomponent of the appliance end-use estimates for the first time in the RECS history.

The annual consumption attributed to each of the end-use categories can be estimated by use of regression equations. 

The regression equations are also used to impute electricity consumption when the billing data are missing or inadequate. 

The dependent variable was the annual electricity consumption for the 1993 calendar year. The desire to use a large 

number of independent variables without using a large number of interaction terms and the desire to adapt the regression 

procedures to account for heteroscedastic 17 error terms led to the use of a nonlinear regression technique. The use of 

linear regression would have greatly restricted the ability to adequately model household energy consumption.

This section of the appendix provides an overview of the methodology used for the 1993 RECS end-use estimation. The 

specific regression equations used are not presented here. (For more detailed information, please contact the person cited 

as the end-use estimation contact on the Contacts page at the beginning of this report.) The procedure used for the 1993 

RECS is very similar to that used in the 1990 RECS. Detailed equations for the 1990 RECS were published in Appendix 

D, "End-Use Estimation Methodology," of Household Energy Consumption and Expenditures 1990 (Energy Information 

Administration, February 1993, DOE/EIA-0321(90)).

1 'Error terms are heteroscedastic when the variance of the error terms is not constant but, instead, is a function of the independent variables.

Energy Information Administration / Energy Consumption Series 

56 Residential Lighting: Use and Potential Savings
Electricity Consumption Equation 

Basic Equation

For electricity, the basic equation is:

Total Consumption = Space-Heating Component

+ Water-Heating Component

+ Air-Conditioning Component

+ Refrigerator Component

+ Appliance Component.

Discussions of each component of the general consumption equation will be followed by a discussion of the nonlinear 

regression technique.

General Space-Heating Component

The space-heating component was defined as all electricity used to generate heat by space-heating equipment. The 

equipment could be the main space-heating equipment or secondary space-heating equipment. Hence, a household could 

have had a positive amount of electricity assigned to the space-heating component even if the electricity source was not 

used as the main space-heating energy source.

For the electricity equation in the 1987 and subsequent RECS, the electricity associated with the operation of fans in any 

central forced-air heating equipment was assigned to the electricity appliance component and not to the space-heating 

component. 18

General Water-Heating Component

The component for water heating was defined as all electricity used to heat water for hot running water, as well as water 

heated at point sources (such as stoves or auxiliary water-heating equipment) for bathing, cleaning and other noncooking 

applications of hot water. Electricity used at point sources to heat water for cooking and hot drinks was considered part 

of the general appliance component, as was electricity used to heat water for a swimming pool, hot tub, spa, or Jacuzzi.

General Air-Conditioning Component

The electricity air-conditioning component was defined as all electricity associated with (1) electric air-conditioning 

equipment and (2) fans in any central air-conditioning equipment including natural gas air-conditioning equipment. The 

regression equations for electricity do not contain specific terms for whole-house fans, window fans, and evaporative 

(swamp) coolers, because the terms were only marginally significant. Hence, the consumption of electricity to operate 

these fans and evaporative coolers was not assigned to the air-conditioning component; it was included in the appliance 

component. 19 The term for ceiling fans is in the electricity appliance component.

'"In previous RECS (prior to 1987), the electricity used to run fans for central forced-air heating systems was assigned to the space-heating 

components. This was changed in the 1987 and subsequent RECS so that the households that did not use electricity as a space-heating energy 

source (either main or secondary), by definition, did not have positive amounts of electricity assigned to the space-heating component.

"Previous RECS (prior to 1987) included a term for evaporative coolers, whole-house fans, ceiling fans, and window fans in the airconditioning component of the electricity equation. Therefore, the consumption of electricity to operate these types of coolers and fans was 

assigned to the air-conditioning component. Consequently, some households that did not have air-conditioning equipment, had positive 

consumption assigned to their air-conditioning component.

Energy Information Administration / Energy Consumption Series

Residential Lighting: Use and Potential Savings 57
In the 1993 RECS, the households that reported that they had air-conditioning equipment but did not use the equipment, 

were assigned a value of zero for their electricity air-conditioning component. In RECS prior to 1987, these households 

were assigned small but positive values for their electricity air-conditioning component.

General Refrigerator Component

The refrigerator component for electricity consisted of all electricity used to operate refrigerators. The electricity used 

to operate freezers that are not part of a refrigerator was assigned to a separate component under General Appliance.

General Appliance Component

The general appliance component consisted of all electricity not used specifically for any of the other end uses. For 

electricity, the general appliance component was split into six subcomponents: (1) Appliance Subcomponent, (2) Lighting 

Subcomponent, (3) Cooking Subcomponent, (4) Dishwasher Subcomponent, (5) Clothes Dryer Subcomponent, and (6) 

Freezer Subcomponent.

Electricity used in appliances during the winter will frequently help heat the housing unit. This secondary effect of the 

appliance consumption was not included in the estimation of the space-heating component. In addition, during the 

summer, energy used in general appliances may add to the load on the air-conditioning system. This was not included 

in the air-conditioning component.

Appliance Subcomponent. The appliance subcomponent consisted of all electricity not used for any of the other five 

subcomponents or the other four main components. This included electricity used to heat water beds, hot tubs and pools, 

and the electricity used to operate fans (including fans for forced-air, space-heating systems), evaporative coolers, water 

pumps, small kitchen appliances (such as toasters, mixers, and can openers), home entertainment equipment (such as 

radios, televisions, stereos, video cassette recorders, electronic games, and computers), and numerous other appliances 

and uses not covered elsewhere.

Lighting Subcomponent. This subcomponent consists of all electricity used for indoor and outdoor lighting.

Cooking Subcomponent. The cooking subcomponent was positive if the household reported that electricity was the 

main cooking fuel; otherwise, the subcomponent was zero. The definition of the subcomponent did not involve the type 

of cooking equipment that was used. Consequently, households with some electric cooking equipment (including 

microwave ovens) could have been assigned a zero value for the electricity cooking subcomponent if the household did 

not list electricity as a cooking fuel. The electricity used to operate the electric cooking equipment in households that 

did not list electricity as a cooking fuel was included in the appliance subcomponent. Similarly, electricity used to 

operate common kitchen appliances, such as toasters and mixers, was included in the appliance subcomponent.

Dishwasher Subcomponent. This subcomponent consisted of all electricity used to operate dishwashers. 

Clothes Dryer Subcomponent. This subcomponent consists of all electricity used to operate clothes dryers.

Freezer Subcomponent. The freezer subcomponent for electricity consisted of all electricity used to operate freezers 

that were not part of a refrigerator.

Nonlinear Regression Technique

The nonlinear regression technique was used to produce electricity end-use estimates for each household. The end-use 

estimates were normalized so that the sum of the end-use estimates was equal to the actual or imputed yearly electricity 

consumption used by the household. The individual household end-use estimates were used to estimate averages and 

totals for end-use consumption over selected household categories. Following is an overview of the basic nonlinear

Energy Information Administration / Energy Consumption Series 

58 Residential Lighting: Use and Potential Savings
equations. (To obtain the detailed equations and individual coefficients, please see the Contacts page at the beginning 

of this report for the end use estimation contact person. 20)

General Regression Equation

The general regression equation splits estimated electricity consumption into its end-use components. The result is:

YCOM = SPHTCOM + WTHTCOM + AIRCCOM + RFRGCOM + APPLCOM, 

where:

YCOM is the estimated annual consumption, 

SPHTCOM is the estimated space-heating component, 

WTHTCOM is the estimated water-heating component, 

AIRCCOM is the estimated air-conditioning component, 

RFRGCOM is the estimated refrigerator component, and 

APPLCOM is the estimated appliance component.

Electricity Regression Equation

The regression equation for electricity splits estimated consumption for the appliance component into six additional 

subcomponents:

YCOM = SPHTCOM + WTHTCOM + AIRCCOM + RFRGCOM 

+ FZZRCOM 

+ DISHCOM 

+ COOKCOM 

+ LITECOM 

+ DRYRCOM 

+ APPSCOM,

where:

FZZRCOM is the estimated freezer subcomponent, 

DISHCOM is the estimated dishwasher subcomponent, 

COOKCOM is the estimated cooking subcomponent, 

LITECOM is the estimated lighting subcomponent, 

DRYRCOM is the estimated clothes dryer subcomponent, and 

APPSCOM is the estimated other appliances subcomponent.

The actual annual consumption is called Y. The unit of measure for Y and YCOM is thousands of Btu. The typical 

regression error term is as follows:

e, = Y - YCOM .

2°For a detailed discussion of the end-use estimation procedures and the correlation of variables, see the National Interim Energy Consumption 

Survey: Exploring the Variability in Energy Consumption, DOE/EIA-072 (Washington, DC, July 1981); the National Interim Energy Consumption 

Survey: Exploring the Variability in Energy Consumption - A Supplement, DOE/EIA-0272/S (Washington, DC, October 1981); and Residential 

Energy Consumption Survey: Regression Analysis of Energy Consumption by End Use, DOE/EIA-0431 (Washington, DC, October 1983).

Energy Information Administration / Energy Consumption Series

Residential Lighting: Use and Potential Savings 59
Unfortunately, the variance of e, tends to increase as YCOM increases. Furthermore, the distribution of e, is skewed 

in the positive direction. These two facts violate the assumptions associated with linear least-squares regression. On 

the other hand, the distribution of

e2 = (Y)'/4 - (YCOMf

is closer to being normally distributed with a constant variance. Hence, a nonlinear least-squares regression procedure 

that minimizes the sum of squares of e2 was used.

The dependent variable was the household's electricity consumption as reported on the RECS Suppliers Survey in 

thousands of Btu. Most of the independent variables are derived from information reported by the individual households 

on the Household Survey. The end-use components consisted of sums or products of terms that themselves may have 

been sums or products of the independent variables. The overall methodology may seem complex at first glance, but 

there was a common structure. In general, the components consisted of an overall term multiplied by various 

adjustments. This format allowed the components to be adjusted by many factors. The relative size of the adjustments 

was easy to determine.

The disadvantage of the format was that it yields a basic equation that is intrinsically nonlinear. As a result, standard 

multivariate linear regression techniques could not be used to estimate the parameters. A nonlinear technique was used 

instead. The parameters were estimated by using the nonlinear regression procedure (PROC NLIN) contained in the 

statistical computer package, SAS. 21

Details of Lighting Component

The lighting component covers the consumption of electricity for both indoor and outdoor lighting. The indoor lighting 

is modeled by using the equation (converted to thousand Btu) developed from the Lighting Supplement as an independent 

variable. Outdoor lighting is modeled by using variables that describe the presence and use of outdoor lights. As with 

all components, the lighting component is multiplied times common adjustment terms. These terms are functions of the 

price of electricity, presence of household members during the day, family income, age of dwelling, housing unit type, 

and demographic characteristics of the house holder.

The resulting equation for the lighting component is given below:

Lighting component = 0.82710 x Yl

+ 1,016.05323 xY2 

+ 1,124.08710 xY3 

+ 1,773.86255 xY4 

+ 339.23403 xY5 

+ 734.26589 xY6 

+ 791.90744 xY7

where

Yl = 3.412 x kWh estimate from second step of Lighting Supplement regression (p 58)

Y2 = Indicator function for presence of outdoor light on all night

Y3 = Indicator function for presence of outdoor light on all night and the light is 150 watts or more

Y4 — Indicator function for presence of outdoor light controlled by a timer but there is not an outdoor light on 

all night

2 'StatisticaI Analysis System (SAS) Institute (Cary, North Carolina).

Energy Information Administration / Energy Consumption Series 

60 Residential Lighting: Use and Potential Savings
Y5 = Indicator function for presence of outdoor light (150 watts or more) controlled by a timer but there is not 

an outdoor light on all night

Y6 = Indicator function for presence of outdoor light on during the evening but there is not an outdoor light on 

all night or one controlled by a timer

Y7 = Indicator function for presence of outdoor light on during the evening (150 Watts or more) but there is not 

an outdoor light on all night or one controlled by a timer.

Energy Information Administration / Energy Consumption Series

Residential Lighting: Use and Potential Savings 61

Appendix C

Data Quality

RECS Compared to Engineering Studies

Data from the RECS can be used to assess potential bias that can occur in engineering studies which are based on small 

samples that may not be representative of the larger population of interest. The RECS sample covers all types of 

households and housing units in the United States, and the sample was selected in such a way that the sampling error of 

its estimates are measured and provided to users along with the estimates themselves.

For example, an engineering study of 53 homes, where two light loggers had been used in each home, produced an annual 

estimate of 2,930 kWh for lighting. 22 The authors noted that it might be dangerous to estimate for all lights in the house 

from a sample of two and they noted that their estimates were higher than estimates commonly used by utilities. The 

study suggested an annual lighting budget for a home of 1,200 to 1,500 kWh. The RECS estimated that only 27 percent 

of households used 1,200 or more kWh for lighting. If the engineering study represented single-family households only, 

the lighting budget still applied to about 25 percent of single-family homes (25 percent of single-family homes used 

between 953 and 1,397 kWh per annum).

It is not certain in this study whether the unusually high estimate, compared to RECS, came from sampling lights that 

were used more often (the authors thought their sample of lights were used less often than other lights in the house) or 

because the sampled of households were high users of lighting. Whichever the source, the unusually high estimates could 

be detected and an estimate derived from RECS data that would quantify how unusual the estimates were. The 

assumption that these high estimates are typical of national usage would lead to bias in any analysis that uses the 

engineering data. Therefore, researchers who conduct small-scale studies purporting to represent a customer base that 

is a cross section of the general population of homes should compare their data to the RECS data.

A recent survey of utility companies inquiring about the prevalence of end-use metering reported that 68 percent did enduse monitoring. The return rate was small, but it is an indication that a number of utilities conduct these studies for use 

in their planning and evaluation. The difference between the RECS lighting estimates and the engineering studies is a 

major issue for them. 23

Bias in RECS Estimates of Lighting Consumption

Data on lighting usage can be collected in several ways. The 1993 RECS used self-reported data gathered during inperson household interviews. Self-reported data can also be collected via phone interviews and diaries. Other methods 

that do not rely on self-reported data include mechanical devices, such as light loggers. To what extent do self-reported 

data, especially in-person self-reported data, give an accurate picture of the amount of time a light is turned on? 

Respondents may have some difficulty knowing how many hours each light in the household is used. They may not be 

home during all of the times that lights are turned on and, even if home, may not know how others in the household are 

using lights.

A study comparing various types of self-reported data to light logger data found that self-reported data gave higher 

estimates of light usage than data from the light loggers.24 Light logger data were 81 percent of the on-site estimates and 

72 percent of the diary estimates. Estimates over the telephone were inflated compared to on-site estimates (on site 

estimates were 72 percent of the telephone estimates). A regression analysis of the RECS electricity consumption data 

yielded a similar result (see Appendix B).

22Bruce Manclark, "Of Sockets, Housecalls. and Hardware," Home Energy, November/December 1991, p. 25. 

"Frazer Dougherty, "The State of DSM End-Use Monitoring," Home Energy, March/April 1994.

"Leslie A. Carlson, et al., "Elements of Residential Efficient Lighting Savings," ACEEE1994 Summer Study on Energy Efficiency in Buildings, 

Tables 3 and 4, p. 8.21.

Energy Information Administration / Energy Consumption Series

Residential Lighting: Use and Potential Savings 63
These findings may lead one to believe that RECS overestimates the amount of electricity used for lighting. While it 

is true that the RECS relies on self-report usage data, those data are not used directly to model electricity consumption 

for lighting. The RECS estimates of the amount of electricity used for lighting are regression-based estimates (see 

Appendix B). They are not based upon light loggers or submetering. For each RECS respondent, the regression 

equation, whose coefficients were estimated by a nonlinear regression procedure, was used to estimate the proportion 

of the total annual electricity consumption that was used for each of 10 end-use categories. Lighting is one of the 

categories. The estimated amount of electricity for each end-use category is the total annual electricity consumption 

(derived from utility bills) times the proportion for the end use. As a consequence, the end-use consumption estimates 

for the 10 categories will add up to the actual total annual electricity consumption. The tendency of respondents to 

overestimate how long lights are on is reflected in the coefficients estimated by the regression procedure.

Energy Information Administration / Energy Consumption Series 

64 Residential Lighting: Use and Potential Savings
Appendix D

Related EIA Information on Energy Consumption

For information about how to obtain these publications, see the inside cover of this report. Please note that the prices 

quoted here are subject to change.

In addition to the reports listed below, data diskettes and public-use data tapes for the residential, residential transporta 

tion, and commercial sectors are available from the National Technical Information Service (NTIS). To obtain infor 

mation on how to order the tapes/diskettes, you may call NTIS at 703-487-4650, FAX number 703-321-8547. Data 

diskettes can also be obtained from the Office of Scientific and Technical Information (OSTI). For OSTI ordering 

information, call 615-576-8401. Data from earlier years than those listed are microfiched. Call NTIS for a copy.

The most recent publication for each of the consumption surveys is available on the Energy Information Administration's 

(EIA) Energy InfoDisc (CD-ROM). This new media provides instant access to comprehensive energy data. Order forms 

for the CD-ROM are available on EIA's Homepage site at http://www.eia.doe.gov.

Residential Sector 

Housing Characteristics

Housing Characteristics, 1993; June 1995. DOE/EIA-0314(93), GPO Stock No. 061-003-00912-3, $23.00. 

Housing Characteristics 1990; May 1992, DOE/EIA-0314(90), GPO Stock No. 061-003-00754-6, $23.00.

Consumption and Expenditures

Household Energy Consumption and Expenditures 1993, October 1995, DOE/EIA-0321(93), GPO Stock No. 061- 

00932-08, $21.00.

Household Energy Consumption and Expenditures 1990; February 1993, DOE/EIA-0321/1(90), GPO Stock No. 061- 

003-00795-3, $22.00.

Household Energy Consumption and Expenditures 199CHS; DOE/EIA-0321/2(90), GPO Stock No. 061-003-00796-1, 

$21.00.

Other Publications on the Residential Sector

Energy Consumption Series—Residential Energy Consumption Survey Quality Profile, March 1996, DOE/EIA0555(96)/1, GPO Stock No. 061-003-00956-5, $6.50.

Energy Consumption Series—Sample Design for the Residential Energy Consumption Survey, August 1994, DOE/EIA0555(94)/1, GPO Stock No. 061-003-00865-8, $6.50.

Energy Consumption Series—User-Needs Study of the 1993 Residential Energy Consumption Survey, September 1993, 

DOE/EIA-0555(93)/2, GPO Stock No. 061-003-00819-4, $13.00..

Energy Information Administration / Energy Consumption Series

Residential Lighting: Use and Potential Savings 65
Residential Transportation Sector

Household Vehicles Energy Consumption 1991; December 1993, DOE/EIA-0464(91), GPO Stock No. 061-003-00652- 

3, $14.00.

Household Vehicles Energy Consumption 1988; February 1990, DOE/EIA-0464(88), GPO Stock No. 061-003-00652-3, 

$11.00.

Commercial Sector

Characteristics of Buildings

Commercial Buildings Characteristics 1992; April 1994, DOE/EIA-0246(92), GPO Stock No. 061-003-00850-0, 

$28.00.

Commercial Buildings Characteristics 1989; June 1991, DOE/EIA-0246(89), GPO StockNo. 061-003-00699-0, $18.00.

Consumption and Expenditures

Commercial Buildings Consumption and Expenditures 1992; April 1995, DOE/EIA-0318(92), GPO Stock No. 061-003- 

00904-2, $31.00.

Commercial Buildings Consumption and Expenditures 1989; April 1992, DOE/EIA-0318(89), GPO Stock No. 061-003- 

00753-8, $25.00.

Other Publications on the Commercial Sector

Energy Consumption Series— Energy End-Use Intensities in Commercial Buildings, September 1994, DOE/EIA0555(94)72, GPO Stock No. 061-003-0087-9, 9.00.

Energy Consumption Series—Assessment of Energy Use in Multibuilding Facilities, August 1993, DOE/EIA-0555(93)/1, 

GPO Stock No. 061-003-00817-8, $7.50.

Energy Consumption Series—User-Needs Study for the 1992 Commercial Buildings Energy Consumption Survey, 

September 1992, DOE/EIA-0555(92)/4, GPO Stock No. 061-003-00770-8, $8.50.

Energy Consumption Series—Lighting in Commercial Buildings; March 1992, DOE/EIA-0555(92)/1, GPO Stock No. 

061-003-00749-0, $6.50.

Industrial Sector

Changes in Energy Intensity in the Manufacturing Sector 1985-1991, October 1995, DOE/EIA-0552(85-91). GPO Stock 

No. 061-003-00925-5, $9.00.

Manufacturing Consumption of Energy 1991, December 1994, DOE/EIA-0512(91), GOP Stock No. 061-003-0087-9, 

$34.00.

Manufacturing Energy Consumption Survey: Consumption of Energy, 1988; May 1991, DOE/EIA- 0512(88), GPO 

Stock No. 061-003-00703-8, $11.00.

Energy Information Administration / Energy Consumption Series 

66 Residential Lighting: Use and Potential Savings
Other Publications on the Transportation and industrial Sector 

Transportation

Describing Current and Potential Markets for Alternative-Fuel Vehicles, March 1996, DOE/EIA-604 (No Cost).

Profile of Motor-Vehicle Fleets in Atlanta 1994, November 1995, DOE/EIA-0601, GPO Stock No. 061-003-00938-7, 

$3.50.

Industrial

Energy Consumption Series—Derived Annual Estimates of Manufacturing Energy Consumption 1974-1988, August 

1992, DOE/EIA-0555(92)/3, GPO Stock No. 061-003-00766-0, $7.00.

Energy Consumption Series—Development of the 1991 Manufacturing Energy Consumption Survey, May 1992, 

DOE/EIA-0555(92)/2, GPO Stock No. 061-003-00757-1, $5.50.

Cross-Sector

Energy Consumption—Measuring Energy Efficiency in the United States' Economy: A Beginning; October 1995, 

DOE/EIA-0555(95)/2, GPO Stock No. 061-003-00935-2, $6.50.

Energy Consumption Series-Buildings and Energy in the 1980's, June 1995, DOE/EIA-0555(95)/1, GPO Stock No. 061- 

003-00914-0, $6.00.

Energy Consumption by End-Use Sector: A Comparison of Measures by Consumption and Supply Surveys; April 6, 

1990, DOE/EIA-0533 (no GPO Stock No. available), $2.50.

Public-Use Diskettes

Note: Diskettes are available through the Office of Scientific and Technical Information (OSTI) and NTIS.

Commercial Buildings Consumption and Expenditures, 1992 data, OSTI - ASCII or dBASE format, order by title, $10 

per diskette (4 diskettes). NTIS - ASCII or dBASE format, order by title, call for prices.

Commercial Buildings Characteristics 1992 data, OSTI - ASCII or dBASE format, order by title, $10 per diskette (4 

diskettes). NTIS - ASCII or dBASE format: Order No. PB-94-504305, call for prices.

Commercial Buildings Energy Consumption Survey 1989 data, OSTI - ASCII format, order by title, $10 per diskette 

(4 diskettes). NTIS - ASCII format: Order No. PB92-504232, $140.

Residential Transportation Energy Consumption Survey 1991 Data, OSTI-ASCII (3 diskettes) or dBASE, order by title, 

$10.00 per diskette (3 diskettes). NTIS-ASCII Order No. PB94-500824, dBASE Order No. PB94-500816.

Residential Transportation Energy Consumption Survey 1988 Data, OTSI - ASCII or dBASE format, order by title, $10 

per diskette (4 diskettes). NTIS - ASCII format: Order No. PB91-507269, dBASE format: Order No. PB91-507277, 

$50 each.

Residential Energy Consumption Survey 1990 Data, OSTI-ASCII (3 diskettes) or dBASE format, order by title, $10.00 

per diskette (2 diskettes). NTIS-ASCII format, Order No. PB93-506103 or dBASE format, Order No. PB93-506095.

Energy Information Administration / Energy Consumption Series

Residential Lighting: Use and Potential Savings 67
Residential Energy Consumption Survey 1987 Data, OSTI - ASCII or dBASE format, order by title, $10 per diskette 

(4 diskettes). NTIS - ASCII format: Order No. PB-91-505115, $130, and dBASE format: Order No. PB-91-505107,

$130.

Nonresidential Buildings Energy Consumption Survey 1986 Dato.OSTI - ASCII format, order by title, $10 per 

diskette (4 diskettes). NTIS - ASCII format: Order No. PB91-506808, $130.

Public-Use Tapes

Note: Public use data from earlier surveys are available on 9-track tapes through NTTS.

Residential and Residential Transportation Sectors

Residential Energy Consumption Survey: 1987 and Residential Transportation Energy Consumption Survey, 1988, 

Order No. PB90-501461, $220.

Residential Energy Consumption Survey: 1984 and Residential Transportation Energy Consumption Survey, 1985; 

Order No. PB87-186540, $220.

Residential Energy Consumption Survey: 1982 and Residential Transportation Energy Consumption Survey, 1983; 

Order No. PB85-221760, $220.

Residential Energy Consumption Survey: Consumption and Expenditures, 1980-1981; Monthly Billing Data; Order No. 

PB84-166230, $220.

Residential Energy Consumption Survey: Housing Characteristics, 1981; Consumption and Expenditures, 1981-1982; 

Monthly Billing Data; Order No. PB84-120476, $220.

Residential Energy Consumption Survey: Housing Characteristics, Annualized Consumption and Expenditures, 1980- 

1981; Order No. PB83-199554, $220.

Residential Energy Consumption Survey: Household Transportation Panel Monthly Gas Purchases and Vehicle and 

Household Characteristics, 6/79-9/81; Order No. PB84-162452, $220.

Residential Energy Consumption Survey: Household Screener Survey, 1979-1980; Order No. PB82-114877, $220.

Residential Energy Consumption Survey: Household Monthly Energy Consumption and Expenditures, 1978-1979; Order 

No. PB82-114901, $220.

National Interim Energy Consumption Survey (Residential), 1978; Order No. PB81-108714, $220.

Commercial Sector

Note: The name of the Nonresidential Buildings Energy Consumption Survey was changed to the Commercial Buildings 

Energy Consumption Survey, beginning with the 1989 survey. The survey name was also dropped from the report title 

at that time and subsequently.

Nonresidential Buildings Energy Consumption Survey: 1986 Data; Order No. PB90-500034, $220. 

Nonresidential Buildings Energy Consumption Survey: 1979 and 1983 Data; Order No. PB88-245162, $220.

Energy Information Administration / Energy Consumption Series 

68 Residential Lighting: Use and Potential Savings
CD-ROM

EIA publications and data are available. For ordering CD-ROM, see EIA's Homepage site located at 

http://www.eia.doe.gov. (Also, see the CD-ROM's contents listing on the Homepage.)

Planned Publications

Profile of Motor-Vehicle Fleets in Denver 1995, planned for November 1996. 

A Guide to Surveys of Motor Vehicle Fleets, planned for December 1996. 

Household Vehicles Energy Consumption 1994, planned for December 1996.

Note: The Energy Information Administration also publishes annually the State Energy Data Report, Consumption 

Estimates, DOE/EIA-0214; the State Energy Price and Expenditures Report, DOE/EIA-0376; and the Monthly 

Energy Review, DOE/EIA-0035. These reports contain annual and monthly consumption information derived from 

EIA supply surveys.

Energy Information Administration / Energy Consumption Series

Residential Lighting: Use and Potential Savings 69

Glossary

Air-Conditioning: Air-conditioning is one of the five end-use categories in this report. It is defined as cooling and 

dehumidification of the air in a building by a refrigeration unit driven by electricity or gas. This definition excludes fans, 

blowers, or evaporative cooling systems ("swamp coolers") that are not connected to a refrigeration unit. 

Air-conditioning units that are not currently in working condition or are not used are still included in the RECS if they 

are in place in the housing unit. If the household did not use its air-conditioning equipment during the summer of 1993, 

no consumption and expenditures are imputed for air-conditioning.

Apartments. A housing unit in a building with multiple units—a structure that is divided into living quarters for more 

than one family or household and where one household lives above another. Apartments can be located in large 

buildings, garden apartment buildings, or in houses originally intended for occupancy by one family (or some other use) 

that have since been converted to separate dwellings for more than one family.

Appliances: One of the main end-use categories in RECS. It is defined as the use of energy for all uses except those 

covered by space heating, water heating, refrigerators (starting with the 1990 RECS), and air-conditioning. This includes 

energy used for freezers, lights, televisions, personal computers, washing machines, and most small appliances. Special 

energy uses for appliances are energy used to heat: food, water for cooking, water for hot drinks, air to dry clothes, water 

for a swimming pool, water in a water bed. Also included is energy to operate fans for a central forced-air space-heating 

system and energy for an evaporative cooling system (swamp coolers). (See End-Use and for a more complete listing 

of appliances, see Appliances Used.)

Appliances Used: Appliances used in the home during the year, including those loaned to the householder for regular 

use. Appliances possessed by the household but not used are not counted, except for air-conditioning equipment. 

Appliances temporarily not in working condition but generally used by the household are included only if a repair person 

has been called or the appliance has been taken to a repair shop, except for air-conditioning equipment. Cooking 

appliances include the following: toaster oven, gas stove-top or burners, gas oven, electric stove-top or burners, electric 

oven, microwave oven, gas grill (that uses bottled gas or propane), and natural gas grill. Stove-top or burners include 

range tops and stand-alone cook tops. Range burners and ovens are counted as separate appliances. Cooling appliances 

include: evaporative cooler (swamp cooler), whole-house or attic fan, exhaust fan, window fan, ceiling fan, portable or 

table fan. Other appliances counted include: refrigerator, freezer, dishwasher, clothes washer and dryer, swimming pool 

and hot tub pump and heater, television, personal computer, laser printer, waterbed heater, heated aquarium, humidifier, 

air cleaner, facsimile machine, photocopier, portable space heater, and dehumidifier.

Average: The simple arithmetic average for a population; that is, the sum of all the values in a population divided by 

the size of the population. Population means are estimated by computing the weighted sum of the sample values, then 

dividing by the sum of the sample weights. (See Weight.)

Ballast: See High-Efficiency Ballast.

Bathroom: For this report, a full bathroom contains a sink with running water, a flush toilet, and a bathtub or shower. 

A half bathroom contains a toilet or bathtub or shower.

Bedroom: Room intended for sleeping, even if not presently used for sleeping. Number of bedrooms are those that 

would be listed as descriptive of the apartment or house if it were on the market for sale or rent. A one-room efficiency 

or studio apartment has no bedrooms.

British Thermal Unit: See Btu.

Btu (British Thermal Unit): A Btu is defined as the amount of energy required to increase the temperature of 1 pound 

of water by 1 degree Fahrenheit, at normal atmospheric pressure. (See Metric Conversion Factors.)

Energy Information Administration / Energy Consumption Series

Residential Lighting: Use and Potential Savings 71
Btu Conversion Factors: The Btu conversion factors used for this survey are listed below:

Electricity (site) 3,412 Btu/kilowatthour

Electricity (primary) 10,280 Btu/kilowatthour25

Natural gas 1,028 Btu/cubic foot

Fuel Oil No.l 135,000 Btu/gallon

Kerosene 135,000 Btu/gallon

Fuel Oil No.2 138,690 Btu/gallon

LPG (propane) 91,330 Btu/gallon

Wood 20,000,000 Btu/cord.

Census Division: A geographic area consisting of several States defined by the U.S. Department of Commerce, Bureau 

of the Census. The States are grouped into nine divisions and four regions.

Region Division States

Northeast New England Connecticut, Maine, Massachusetts,

New Hampshire, Vermont, and Rhode Island

Middle Atlantic New Jersey, New York, and Pennsylvania

Midwest East North Central Illinois, Indiana, Michigan,

Ohio, and Wisconsin

West North Central Iowa, Kansas, Minnesota, Missouri,

Nebraska, North Dakota, and South Dakota

South South Atlantic Delaware, the District of Columbia,

Florida, Georgia, Maryland, North 

Carolina, South Carolina, Virginia, 

and West Virginia

East South Central Alabama, Kentucky, Mississippi,

and Tennessee

West South Central Arkansas, Louisiana, Oklahoma,

and Texas

West Mountain Arizona, Colorado, Idaho, Montana,

Nevada, New Mexico, Utah, and Wyoming

Pacific Alaska, California, Hawaii, Oregon,

and Washington

Census Region: See Census Division.

Clothes Dryer: An appliance that dries laundry through the application of heat and rapid air movement. The hot air 

used is typically heated by electricity or gas, either natural gas or liquefied petroleum gas.

Clothes Washer: An appliance for automatically cleaning home laundry. It has an opening on its top or its front 

offering access to the washer tub. An agitator, located within the tub, moves the articles to be cleaned through the wash 

water. The machine is powered by an electric motor connected to the tub and agitator via a transmission, clutches, and 

linkages. In front-loading machines, the articles are moved by a rotating tube rather than an agitator.

-'Average energy input of the generation process for fossil-fuel utility plants in the United States for 1993. See Table A8, Energy Information 

Administration, Monthly Energy Review, August 1996, p. 143.

Energy Information Administration / Energy Consumption Series 

72 Residential Lighting: Use and Potential Savings
Consumption: The amount of electricity or natural gas used by, or delivered to, the household during a 365-day period. 

For fuel oil, kerosene, and LPG, the quantity represents fuel purchased, not fuel consumed. If the level of fuel in the tank 

was the same at the beginning and end of the annual period, then the quantity consumed would be the same as the 

quantity purchased. Measurements or reports of the level of fuel in the tank were not included in the RECS data 

collection.

Conversion Factors: See Btu Conversion Factors and Metric Conversion Factors.

Demand-Side Management (DSM) Programs: These are organized utility-sponsored activities that are intended to 

affect the amount and timing of customer electricity or natural gas use.

Dishwasher: A built-in or portable appliance used for automatically cleaning dishware, utensils, and cutlery. The 

national appliance efficiency standards required that, by 1988, dishwashers be equipped with an option to dry without 

heat.

Electricity: Metered electric power supplied by a central utility company to a residence via power lines. Since there 

are no volumetric measures of electricity, as there are with the fossil fuels, electricity is measured as the amount of power 

used at any instant (demand expressed in watts or kilowatts) or as power used over a given time (consumption expressed 

in kilowatthours). The heat equivalent for electricity is 3,412 Btu per kWh, but this is a derived form of energy and does 

not represent the amount of energy needed to generate the electricity and transmit it to the building. Generation and 

transmission requires about 3 times 3,412 Btu per kWh. Energy is used in preparing other fuels for consumption from 

their condition as mined and delivering them to a site for use, but these amounts of energy are relatively small compared 

to the Btu value of the fuel consumed. (See Primary Electricity and Btu Conversion Factors.)

End Use: A function for which energy sources or fuels are used in the household. Five main energy end-use categories 

were estimated: space heating, air-conditioning, water heating, refrigerator, and appliance usage. The amount of energy 

used for these end uses is estimated by means of a nonlinear regression technique, rather than by using metered data. 

Although not shown in the tables in Chapter 5, end-use estimates were also made for the following uses of electricity: 

freezers, lighting, dishwashers, clothes dryers, and cooking (ranges and ovens). (See Appendix B, "End-Use Estimation 

Methodology.")

Energy: The capacity for doing work as measured by the capability of doing work (potential energy) or the conversion 

of the capability to motion (kinetic energy). Energy has several forms, some of which are easily convertible and can be 

changed to another form useful for work. Most of the world's convertible energy comes from fossil fuels that are burned 

to produce heat that is then used as a transfer medium to mechanical or other means in order to accomplish tasks. 

Electrical energy is usually measured in kilowatthours, while heat energy is usually measured in British thermal units 

(Btu).

Expenditures: Charges spent for the energy consumed in, or delivered to, a building during a given period of time. For 

this report, all expenditure statistics are presented on an annual basis, for calendar year 1993. The total dollar amount 

includes State and local taxes but excludes merchandise, repairs, or special service charges. For households on a budget 

plan, the expenditures are for the actual consumption. Electricity and natural gas expenditures are for the amount of those 

energy sources consumed. Fuel oil, kerosene, and LPG expenditures are for the amount of fuel purchased, which may 

differ from the amount of fuel consumed. For households that do not pay their fuel supplier directly, the expenditures 

for fuels are estimated and included in the tables. (See Consumption.)

Family Income Category: The income grouping for the total combined income (before taxes and deductions) of all 

members of the family from all sources, for the 12 months prior to the interview. Sources of income include the 

following: wages, salaries, tips, commissions, interest, dividends, rental income, Social Security or railroad retirement, 

pensions, food stamps, Aid to Families with Dependent Children, unemployment compensation, Supplemental Security 

Income, General Assistance and other public assistance. This definition includes the total income of all family members 

who lived in the household during the 12 months prior to the interview, regardless of whether they were living there at 

the time of the interview. Income of nonfamily members of the household is not included. "Family" includes the 

following types of relationships: mother, father, sister, brother, son, daughter, father-in-law, uncle, aunt, niece, 

grandchild, foster child (and similar relationships).

Energy Information Administration / Energy Consumption Series

Residential Lighting: Use and Potential Savings 73
Floodlights: Lights that illuminate large areas, often used outdoors. Incandescent floodlights, the most common, are 

at least 150 watts. Mercury vapor or sodium vapor floodlights are at least 100 watts. Floodlights cannot be fluorescent 

lights.

Floorspace: The floor area of the housing unit that is enclosed from the weather. For RECS, the following are included 

in the floorspace: basements, whether or not they contain finished space; finished and/or heated space in attics; and 

garages, if they have a wall in common with the house. Not included are: crawl spaces, even if they are enclosed from 

the weather; and sheds and other buildings that are not attached to the house. Floorspace (in square feet) is derived from 

an actual measurement made by the RECS interviewer using a metallic, retractable, 50-foot tape measure.

"Heated Floorspace" is the portion of the floorspace that is heated during most of the winter season. Rooms that are shut 

off during the heating season to save fuel are not counted as heated square footage. Attached garages that are unheated 

and unheated areas in basements and attics are not counted as heated square feet.

"Cooled Floorspace" is computed as total floorspace times the percentage of rooms that are cooled over total rooms. 

This method for calculating cooled floorspace is different from the method used in Housing Characteristics 1993 that 

used heated floorspace rather than total floorspace.

Fluorescent Lamps: Usually long, narrow, white tubes connected to a fixture at both ends; some are circular. The tube 

is coated on the inside with fluorescent material. The lamp produces light by passing electricity through mercury vapor, 

which causes the fluorescent coating to glow or fluoresce. These lights are typically found in kitchen and basement work 

areas. Newer types ("compact" fluorescent lamps), looking somewhat more like a conventional bulbs, can be screwed 

into fixtures. (See Lights.)

Halogen Lamp: A type of incandescent lamp that lasts much longer and is more efficient than the common incandescent 

lamp. The lamp uses a halogen gas, usually iodine or bromine, that causes the evaporating tungsten to be redeposited 

on the filament, thus prolonging its life. (See Incandescent Lamp.)

Heated Floorspace: See Floorspace.

High-Efficiency Ballast (HEB): The ballast is the transformer for florescent and High-Intensity Discharge Lamps, 

which provides the necessary current, voltage, and wave-form conditions to operate the lamp.

High-Intensity Discharge (HID) Lamp: A lamp that produces light by passing electricity through gas, which causes 

the gas to glow. Examples of HID lamps are mercury vapor lamps, metal halide lamps, and high-pressure sodium lamps. 

HID lamps have an extremely long life and emit far more lumens per fixture than do florescent lights.

Household: A family, an individual, or a group of up to nine unrelated persons, occupying the same housing unit. 

"Occupy" means the housing unit was the person's usual or permanent place of residence at the time of the first field 

contact. Household members include babies, lodgers, boarders, employed persons who live in the housing unit, and 

persons who usually live in the household but are away traveling or in a hospital. The household does not include (1) 

persons who are normally members of the household but who were away from home as college students or members of 

the armed forces at the time of the contact; (2) persons temporarily visiting with the household if they have a place of 

residence elsewhere; (3) persons who take their meals with the household but usually lodge or sleep elsewhere; (4) 

domestic employees or other persons employed by the household who do not sleep in the same housing unit; and (5) 

persons who are former members of the household, but have since become inmates of correction or penal institutions, 

mental institutions, homes for the aged or needy, homes or hospitals for the chronically ill or handicapped, nursing 

homes, convents or monasteries, or other places in which residents may remain for long periods of time. By definition, 

in the RECS, the number of households is the same as the number of occupied housing units.

Household Member: See Household.

Householder: The person (or one of the people) in whose name the home is owned or rented. If there is no lease or 

similar agreement, or if the person who owns the home or pays the rent does not live in the housing unit, the householder 

is the person responsible for paying the household bills, or whoever is generally in charge.

Energy Information Administration / Energy Consumption Series 

74 Residential Lighting: Use and Potential Savings
Housing Unit: A house, an apartment, a group of rooms, or a single room if it is either occupied, or intended for 

occupancy, as separate living quarters by a family, an individual, or a group of one to nine unrelated persons. Separate 

living quarters means the occupants (1) live and eat separately from other persons in the house or apartment and (2) have 

direct access from the outside of the building or through a common hall—that is, they can get to it without going through 

someone else's living quarters. Housing units do not include group quarters, such as prisons or nursing homes where ten 

or more unrelated persons live. Hotel and motel rooms are considered housing units if occupied as the usual or 

permanent place of residence.

Incandescent Lamp: The most common and among the least energy-efficient of all household lamps. A lamp that 

produces light by electrically heating a tungsten filament so that it glows and produces a soft, warm light. Because so 

much of the energy used is lost as heat, these are highly inefficient sources of light. Included in this category are the 

familiar household light bulbs that screw into sockets, as well as more energy-efficient incandescent bulbs, such as 

Tungsten Halogen (spotlights), Reflector or R-lamps (accent and task lighting), Parabolic Aluminized Reflector (PAR) 

lamps (flood and spot lighting), and Ellipsoidal Reflector (ER) lamps (recessed lighting).

Intensity: This is a method of adjusting either the amount of energy consumed or expenditures spent, for the effects of 

various housing unit and/or household characteristics, such as size of the housing unit, climate, and number of household 

members, to facilitate comparisons of energy across time, regions of the country, fuels, and housing units.

Kilowatthour: See kWh.

kWh (Kilowatthour): A unit of work or energy, measured as 1 kilowatt (1,000 watts) of power expended for 1 hour. 

One kWh is equivalent to 3,412 Btu. (See Btu and Btu Conversion Factor.)

Lamp: A term generally used to describe a manmade source of light. The term is often used when referring to a "bulb" 

or "tube." (See Lights.)

Lights: For the RECS, all of the light bulbs controlled by one switch were counted as one light. For example, a 

chandelier with multiple lights controlled by one switch is counted as one light. A floor lamp with two separate globes 

or bulbs controlled by two separate switches would be counted as two lights. Indoor and outdoor lights were counted 

if they were under the control of the householder. This would exclude lights in the hallway of multifamily buildings. 

(See Floodlights, Fluorescent, High-Intensity Discharge, and Incandescent Lamps.)

Metric Conversion Factors: In this report, estimates are presented in customary U.S. units. Floorspace estimates may 

be converted to metric units by using this relationship: 1 square foot is approximately equal to .0929 square meters. 

Energy estimates may be converted to metric units by using this relationship: 1 Btu is approximately equal to 1,055 

joules. One kilowatthour is exactly equal to 3,600,000 joules. One gigajoule is approximately 278 kilowatthours (kWh). 

(See Btu and Btu Conversion Factors.)

Mobile home: A housing unit built on a movable chassis and moved to the site. It may be placed on a permanent or 

temporary foundation and may contain one room or more. If rooms are added to the structure, it is considered a 

single-family housing unit. A manufactured house assembled on site is a single-family housing unit, not a mobile home.

Occupied Housing Unit: A unit in which someone was living as his or her usual or permanent place of residence when 

the first RECS field contact was made. (See Housing Unit.)

Owned/Rented: The relationship of a housing unit's occupants to the structure itself, not the land on which the structure 

is located. "Owned" means the owner or co-owner is a member of the household and the housing unit is either fully paid 

for or mortgaged. A household is classified "rented" even if the rent is paid by someone not living in the unit. Rent free 

means the unit is not owned or being bought and no money is paid or contracted for rent. Such units are usually provided 

in exchange for services rendered or as an allowance or favor from a relative or friend not living in the unit. Unless 

shown separately, rent-free households are grouped with rented households.

Ownership: See Owned/Rented.

Peak Demand: The maximum rate of energy consumption per unit time over a period of measurement.

Energy Information Administration / Energy Consumption Series

Residential Lighting: Use and Potential Savings 75
Potential Savings: Savings that could be realized if households adopted more energy-efficient equipment and 

appliances, such as compact fluorescent lights.

Primary Electricity: A measurement of electricity that includes the approximate amount of energy used to generate 

electricity. To approximate the adjusted amount of electricity, the site-value of the electricity is multiplied by a factor 

of three. This conversion factor of three is a rough approximation of the Btu value of raw fuels used to generate 

electricity in a steam-generation power plant. In this report, electricity is represented as site energy. (See Site Energy 

and Btu Conversion Factors.)

Relative Standard Error: See RSE or Relative Standard Error. 

Rent: See Owned/Rented.

Residential: Occupied housing units, including mobile homes, single-family housing units (attached and detached), and 

apartments. The definition of "occupied housing units" is the same as that used by the U.S. Bureau of the Census. (See 

Household and Housing Unit.)

Residential Building: A structure used primarily as a dwelling for one or more households.

Rooms: Subdivisions of a housing unit. Whole rooms are rooms such as living rooms, dining rooms, bedrooms, 

kitchens, lodgers' rooms, finished basements or attic rooms, recreation rooms, and permanently enclosed sun porches 

that are used year round. Rooms used for offices by a person living in the unit are included in this survey. "Finished" 

means that the ceiling and walls are covered with finishing materials.

Not considered to be rooms in this survey are bathrooms, halls, foyers, or vestibules, balconies, closets, alcoves, pantries, 

strip or Pullman kitchens, laundry or furnace rooms, unfinished attics or basements, open porches, and unfinished space 

used for storage.

A partially divided room, such as a dinette next to a kitchen or a living room, is considered a separate room only if there 

is a partition from floor to ceiling—but not if the partition consists solely of shelves or cabinets. If a room is used by 

occupants of more than one unit, the room is included with the unit from which it is most easily reached. (See Bedroom 

and Bathroom.)

RSE Column Factor: An adjustment factor used to compute RSE's. For a survey estimate in a particular row and 

column of a table (that is, a particular "cell"), the approximate RSE is obtained by multiplying the RSE row factor by 

the RSE column factor for that cell (See RSE or Relative Standard Error, RSE Row Factor).

RSE or Relative Standard Error: A measure of the reliability or precision of a survey statistic. The Relative Standard 

Error, or RSE, is defined as the standard error of a survey estimate, expressed as a percent of the estimate. For example, 

an RSE of 10 percent means that the standard error is one-tenth as large as the survey estimate. The RSE is also known 

as the coefficient of variation.

RSE Row Factor: A factor used to compute RSE's. The row factor is equal to the geometric mean of the RSE's in a 

particular row of main tables. For a survey estimate in a particular row and column of a table (that is, a particular "cell"), 

the approximate RSE is obtained by multiplying the RSE row factor by the RSE column factor for that cell. (See RSE 

or Relative Standard Error, RSE Column Factor.)

Sampling: The procedure used to select housing units for interview from the population of all residential housing units 

in the United States.

Single-Family: A housing unit that provides living space for one household or family. The structure may be detached 

or attached to another unit. Attached houses are considered single-family houses as long as the house itself is not divided 

into more than one housing unit and has an independent outside entrance. A single-family house is contained within 

walls that go from the basement (or the ground floor, if there is no basement) to the roof. Townhouses, rowhouses, and 

duplexes are considered single-family attached housing units, as long as there is no household living above another one

Energy Information Administration / Energy Consumption Series 

76 Residential Lighting: Use and Potential Savings
within the walls that go from the basement to the roof to separate the units. A mobile home with one or more rooms 

added is classified as a single-family home.

Site Energy: The Btu value of energy at the point it enters the home, sometimes referred to as "delivered" energy. In 

this report, electricity is represented as site electricity. (See Primary Electricity and Btu Conversion Factors.)

Space Heating: The use of mechanical equipment (including wood stoves and active solar-heating devices) to heat all, 

or part, of a building to at least 50 degrees Fahrenheit. The equipment could be the main space-heating equipment or 

secondary space-heating equipment. It does not include the use of energy to operate appliances (such as lights, 

televisions, and other appliances) that give off heat as a byproduct.

Square Feet: See Floorspace.

Weight: The number of households in the United States that a particular sample unit represents. To estimate the total 

value of an attribute (such as floorspace) in the U.S. residential population as a whole, each sample household's value 

is multiplied by the household's weight. Summing the weighted sample values provides an estimate of the nationwide 

total.

Energy Information Administration / Energy Consumption Series

Residential Lighting: Use and Potential Savings 77

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