4 RESIDENTIAL ENERGY 1997 OVERVIEW: MOST POPULOUS STATES Number of households: 11.5 million Single-family homes: 68% Multifamily dwellings: 28% Owner-occupied homes: 54% Homes built... ... before 1940: 10% ... after 1980: 25% Homes with a ... ... basement1: 7% ... garage or carport: 59% ... clothes washer: 61% ... personal computer: 40% Homes using ... ... natural gas: 84% ... LPG: 4% Eligible for the Low-Income Home Total energy consumed: 64 million Btu per household Homes where main space heating energy source was... ... electricity: 25% Energy consumed for space heating: 20 million Btu per household Homes with air-conditioning: 40% ... with a central air-conditioning system: 28% ... with room/wall units: 12% Electricity consumed for air conditioning2: 4 million Btu per household RESIDENTIAL ENERGY 1997 OVERVIEW: MOST POPULOUS STATES Number of households: 6.8 million Total energy consumed: 123 million Btu per household Homes where main space heating energy source was... ... natural gas: 50% ... fuel oil: 40% ... electricity: 6% Energy consumed for space heating: 77 million Btu per household Homes with air-conditioning: 62% with a central air-conditioning system: 18% ... with room/wall units: 44% Electricity consumed for air conditioning2: 2 million Btu per household Changes in Energy Consumption and Related Household Characteristics The 1997 Residential Energy Consumption Survey (RECS) was the tenth administration of the survey since 1978. Over the 19 years between the first and last surveys, energy consumption and related household characteristics in U.S. households have changed significantly. This section of this report describes some of the more notable changes documented by the RECS. The fuels consumed in U.S. households are usually measured in physical units: electricity in kilowatthours; natural gas in cubic feet; fuel oil, kerosene, and liquefied petroleum gas in gallons; and wood in cords. For comparisons across fuels to be made, a common measure is necessary. Hence, the physical units have all been converted to Btu (British thermal units). (For the factors used to convert physical units to Btu, see Btu Conversion Factors in the Glossary.) U.S. Housing Units Over the past two decades, the number of U.S. housing units increased by 33 percent. When the first RECS was conducted in 1978, there were 76.6 million housing units in the United States. When the 1997 RECS was conducted, the number had increased to 101.5 million units (Figure 2.1). Figure 2.1. Number of U.S. Housing Units, 1978-1997 At the same time that the number of housing units was increasing, the size of housing units in the United States also became increasingly larger, resulting in an increased demand for energy-consuming activities, such as heating, airconditioning, and lighting. The percentage of smaller housing units, those with four or fewer rooms (excluding bathrooms), decreased from 35 percent to 30 percent (Figure 2.3). At the other end of the scale, the percentage of larger housing units, those with seven or more rooms, increased from 22 percent in 1978 to 29 percent in 1997. Energy Consumption Energy consumption can be expressed as the amount of energy consumed within the housing unit (site energy) or it can include the energy consumed in generating and Energy Information Administration Primary and Site Energy Primary energy is the sum of the energy directly consumed by end users (site energy) and the energy consumed in the production and delivery of energy products. Electricity, of the major energy sources, has the greatest disparity between primary and site energy-a vastly greater amount of energy is used to generate and transmit electricity than to produce and distribute the other major sources. In 1997, steam-electricity utility plants, which were the largest source of electricity generation, were estimated to have used approximately 3.02 Btu of fossil-fuel energy to generate 1 Btu of electricity. Thus, in keeping with EIA policy, primary energy, as measured in this report, is the sum of site energy and electricity losses. The choice of expressing energy consumption data as site energy or primary energy (or site electricity or primary electricity, when that energy source alone is considered) depends on how the data are used. Site energy and site electricity reflect the amount actually consumed within the housing unit. Primary energy and primary electricity data are useful to policymakers, energy analysts, and others, who are concerned with environmental issues, such as carbon emissions from energy sources. The consumption data presented in previous RECS have been expressed as site energy and site electricity. Primary electricity data are presented in the tables in the Total Consumption section of the 1997 RECS Detailed Data Tables (Chapter 4 of this report). Energy Information Administration |