Glossary

The Glossary is divided into six distinct sections: General Terminology, Residential Sector, Commercial Buildings Sector, Transportation Sector, Industrial Sector, and the U.S. Economy.

General Terminology

Behavioral Change: As it affects energy efficiency, behavioral change is a change in energy-consuming activity originated by, and under control of, a person or organization. An example of behavioral change is adjusting a thermostat setting, or changing driving habits.

British Thermal Unit (Btu): The quantity of heat needed to raise the temperature of 1 pound of water by 1 degree Fahrenheit at or near 39.2 degrees Fahrenheit.

Census Region: A geographic area consisting of several States defined by the U.S. Department of Commerce, Bureau of the Census. The four Census regions are:

Northeast: Connecticut, Maine, Massachusetts, New Hampshire, Vermont, Rhode Island, New Jersey, New York, and Pennsylvania

Midwest: Illinois, Indiana, Michigan, Ohio, Wisconsin, Iowa, Kansas, Minnesota, Missouri, Nebraska, North Dakota, and South Dakota

South: Delaware, District of Columbia, Florida, Georgia, Maryland, North Carolina, South Carolina, Virginia, West Virginia, Alabama, Kentucky, Mississippi, Tennessee, Arkansas, Louisiana, Oklahoma, and Texas

West: Arizona, Colorado, Idaho, Montana, Nevada, New Mexico, Utah, Wyoming, Alaska, California, Hawaii, Oregon, and Washington

Cooling Degree-Days (CDD): A measure of how hot a location was over a period of time, relative to a base temperature. In this report, the base temperature is 65 degrees Fahrenheit; the period of time is 1 year. The CDD for a single day is the difference between that day's average temperature and 65 degrees, if the daily average exceeds the base temperature, and zero if the daily average is less than or equal to the base temperature. The CDD for a longer period of time is the sum of the daily CDD from the days in the period.

Demand Indicator: A measure of the number of energy-consuming units, or the amount of service or output, for which energy inputs are required.

Establishment: As defined by the 1987 Standard Industrial Classification Manual,"...an economic unit generally at a single physical location, where business is conducted or where services or industrial operations are performed." (See Manufacturing Establishment.)

End Use: Any specific activity performed by a sector (residential, commercial, industrial, or transportation) that requires energy, e.g., refrigeration, space heating, water heating, manufacturing process, feedstocks, etc.

Energy Efficiency: A value-based, philosophical concept. In this report, two different concepts of energy efficiency are discussed, a technical and a more broad, subjective concept. In the technical concept, increases in energy efficiency take place when either energy inputs are reduced for a given level of service or there are increased or enhanced services for a given amount of energy inputs. In the more subjective concept, energy efficiency is the relative thrift or extravagance with which energy inputs are used to provide goods or services.

Energy Intensity: The ratio of energy consumption to a measure of the demand for services (e.g., number of buildings, total floorspace, floorspace-hours, number of employees, or constant dollar value of Gross Domestic Product for services).

Floorspace: The area enclosed by exterior walls of a building, including parking areas, basements, or other floors below ground level. It is measured in square feet.

Heated Floorspace: The area within a building, which is space heated.

Cooled Floorspace: The area within a building, which is air-conditioned.

Gross Domestic Purchases: The total purchases by U.S. residents for all goods and services wherever produced, including imports, but excluding exports. The scope of energy expenditures and price is more consistent with that of gross domestic purchases than gross domestic product. Gross domestic purchases figures are reported in real 1987 dollars, using the implicit price deflator published by the U.S. Department of Commerce, Bureau of Economic Analysis. See Appendix A, "Additional Measures of Energy Consumption, Expenditures, and Prices" in State Energy Price and Expenditure Report 1992 (DOE/EIA-0376(92)) for a further treatment of the usage of gross domestic purchases.

Gross Domestic Product (GDP): The total value of goods and services produced by the Nation's economy before deduction of depreciation charges and other allowances for capital consumption labor and property located in the United States. It includes the total output of goods and services by private consumers and government, gross private domestic capital investment, and net foreign trade. GDP figures are reported in real 1987 dollars, using the implicit price deflator published by the U.S. Department of Commerce, Bureau of Economic Analysis.

Heating Degree-Days (HDD): A measure of how cold a location was over a period of time, relative to a base temperature. In this report, the base temperature is 65 degrees Fahrenheit; the period of time is 1 year. The HDD for a single day is the difference between that day's average temperature and 65 degrees, if the daily average is below the base temperature, and zero if the daily average exceeds or equals the base temperature. The HDD for a longer period is the sum of daily HDD for days in that period.

Normal Cooling Degree-Days: Annual cooling degree-day average over 30 years from 1961 through 1990 as calculated by U.S. Department of Commerce, National Oceanic and Atmospheric Administration (NOAA).

Normal Heating Degree-Days: Annual heating degree day average over 30 years from 1961 through 1990 as calculated by U.S. Department of Commerce, National Oceanic and Atmospheric Administration (NOAA).

Primary Energy Consumption: Primary energy consumption is the amount of site consumption, plus losses that occur in the generation, transmission, and distribution of energy (See Site Energy Consumption.).

Sector: The broadest category for which energy consumption and intensity are considered within the U.S. economy. For this report, four major energy-using sectors are considered: residential, commercial buildings, transportation, and industrial.

Site Energy Consumption: The Btu value of energy at the point it enters the home, building, or establishment, sometimes referred to as "delivered" energy. (See Primary Energy Consumption.)

Structural Change: As it affects energy efficiency, structural change is a change in the relative levels of energy-consuming subsectors within a sector. An example of structural change is change in product or industry mix in the industrial sector.

Residential Sector

End Use: A function for which energy sources or fuels are used in the household. Any specific activity performed requires energy. For the residential sector, the following main energy end-use categories are estimated using RECS data. See Appendix D, "End-Use Estimation Methodology," in Household Energy Consumption and Expenditures 1990 (DOE/EIA-0321(90)).

Space Heating: The use of mechanical equipment to heat all or part of a building to at least 50 degrees Fahrenheit. Includes both the main space-heating and secondary space-heating equipment, but excludes energy used to operate appliances that give off heat as a byproduct.

Air-Conditioning or Cooling: Conditioning of room air for human comfort by a refrigeration unit (e.g., air- conditioner or heat pump) or by circulating chilled water through a central cooling or district cooling system.

Appliances: Energy-consuming equipment used in the home during the year for purposes other than condition of air or centralized water heating. Includes cooking appliances (gas stoves, gas ovens, electric stoves, electric ovens, microwave ovens, and propane or gas grills); cooling appliances (evaporative coolers, attic fans, window or ceiling fans, portable or table fans); and refrigerators, freezers, clothes washers, electric dishwashers, electric clothes dryers, outdoor gas lights, electric dehumidifiers, personal computers, electric pumps for well water, black and white television sets, color televisions, water bed heaters, swimming pools, swimming pool heaters, hot tubs, and spas.

Water Heating: The use of energy to heat water for hot running water, as well as the use of energy to heat water on stoves and in auxiliary water-heating equipment for bathing, cleaning and other noncooking applications of hot water. An automatically controlled, thermally insulated vessel designed for heating water and storing heated water at temperatures less than 180 degrees Fahrenheit.

Household: A family, individual, or group of up to nine unrelated persons, occupying the same housing unit. "Occupancy" means the housing unit was the person's usual or permanent place of residence at the time of the survey. By definition, the number of households is the same as the number of occupied housing units.

Household Member: Any eligible person who belongs to a household. Members include babies, boarders, lodgers, employed persons who live in the housing unit, and persons who usually are part of the household but are away traveling or in a hospital. Excluded are college students who live elsewhere, members of the armed forces, corrections inmates who used to live in the residence, or others who remain away from the residence for extended periods of time.

Housing Unit: A house, apartment, group of rooms, or a single room if it is occupied or intended for occupancy, as separate living quarters by a family, individual, or group of one to nine unrelated persons. Prisons and nursing homes are excluded.

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 or more rooms.

Multifamily (2-4 units): A unit in a building with two to four housing units--a structure that is divided into living quarters for two, three, or four families or households and in which one household lives above another.

Multifamily (5+ units): A unit in a building with five or more housing units--a structure that contains living quarters for five or more families or households and in which one household lives above another.

Single-Family Attached: A structure that provides living space for one family or household that is not divided into multiple housing units and has an independent outside entrance. Townhouses, rowhouses, and duplexes are considered single-family attached housing units, as long as there is no household living above another one within the walls that go from the basement to the roof to separate the units.

Single-Family Detached: A stand-alone structure that provides living space for one household or family. A manufactured house assembled on site is a single-family detached unit, not a mobile home.

Income Level: 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 survey. Sources of income include wages, salaries, tips, commissions, interest, dividends, rental income, social security or retirement, pensions, food stamps, Aid to Families with Dependent Children, unemployment compensation, and other public assistance. Income from unrelated household members is not included.

Main Heating Fuel: The fuel used most for space heating.

New Construction: The amount of square footage constructed in the survey year and two years prior, e.g., 1988-1990 for the 1990 Residential Energy Consumption Survey.

Personal Consumption Expenditures: All household expenditures on durable goods such as stoves, and nondurable goods such as energy, and on services such as day care.

Residential Building: A structure used primarily as a dwelling for one or more households. A building typically containing less than 1,000 square feet of floorspace and intended for human occupancy. More than 50 percent of its floorspace must be used for residential activities.

Unadjusted Energy Consumption: Site energy consumption as provided in the RECS Public-Use Files. No adjustments were made to account for weather variations, behavioral, or structural effects.

Commercial Building Sector

Air-Condition or Cooling: Conditioning of room air for human comfort by a refrigeration unit (e.g., air-conditioner or heat pump) or by circulating chilled water through a central cooling or district cooling system that circulates chilled water.

Commercial Building: A building with more than 50 percent of its floorspace used for commercial activities. Commercial building include, but are not limited to, stores, offices, schools, churches, gymnasiums, libraries, museums, hospitals, clinics, warehouses, and jails. Government buildings are included except for buildings on sites with restricted access, such as some military bases or reservations. A building is an enclosed structure containing over 1,000 square feet of floorspace and intended for human occupancy. Agricultural, industrial, and residential buildings are excluded from commercial sector surveys.

Employee: A worker in a building during the main shift on a typical workday during the year, including self-employed and volunteers. Excluded are customers, patients, and students, unless they are working for the business. Also excluded are employees who work out of the office, e.g., salespeople, delivery people, and messengers.

Major Fuels: The energy sources or fuels for which consumption and expenditure data were collected on four CBECS surveys. These include electricity, natural gas, fuel oil, and district heat. Propane is excluded from all totals.

New Construction: The amount of square footage constructed in the survey year and 2 years prior, e.g., 1990-1992 for the 1992 CBECS.

Occupied Floorspace: The area of all commercial buildings excluding those buildings classified as vacant and all other buildings that were more than 50 percent vacant during the three months preceding the survey.

Principal Building Activity: The activity or function occupying the most floorspace in the building. The categories were designed to group buildings that have similar patterns of energy consumption. While all calculations in this report were performed using 13 categories, the results were aggregated into the following 10 categories:

Education: refers to buildings that house academic or technical classroom instruction. Certain buildings in educational facilities are excluded from this category, e.g., administration (office), dormitory (lodging), gymnasium (assembly), etc.

Food: refers to buildings used for retail or wholesale of food. Includes establishments that sell food retail or wholesale (e.g., grocery stores) and establishments that prepare and sell food and beverages for consumption (e.g., restaurants). (Combines Food Sales and Food Service)

Health Care: covers diagnostic and treatment facilities for both inpatient (e.g., hospitals, rehabilitation facility) and outpatient (e.g., dental, medical, and mental health clinics) care.

Lodging: includes establishments that offer multiple accommodations for short- or long-term residents (e.g., hotels, nursing homes).

Mercantile and Service: refers to buildings used for the sales and displays of goods or services, including automotive, retail, laundry, and shopping centers, but excluding food.

Office: refers to buildings used for general office space, professional offices, and administrative offices.

Assembly: signifies buildings used for gathering of people for social, recreational, cultural, or religious activities, whether in private or public meeting halls. (Combines assembly with religious buildings.)

Warehouse: describes buildings used to store goods, products, merchandise or raw materials, including both refrigerated storage and unrefrigerated warehouses.

Vacant: designates buildings in which more floorspace was vacant than was used for any other single activity.

Other: includes parking garages, public order and safety buildings used in the preservation of law and order or safety, laboratories that use equipment for experimental testing or analysis, and Other buildings not elsewhere classified (e.g., hangars, public restrooms). (Includes the Public Order and Safety Building category.)

Unadjusted Consumption: Major site fuel consumption as provided in the CBECS Public Use Files, excluding consumption of propane and consumption by small floorspace (less than 1,000 square feet) and noncommercial (agriculture, industrial, or residential) buildings.

Ventilation: The circulation of air through a building to deliver fresh air to occupants.

Vintage: The year of origin or age since the construction of a commercial unit, as calculated from the CBECS survey year.

Transportation Sector

Air Travel: Include both general aviation and commercial air carriers. General aviation refers to the use of non-commercial air carriers for several purposes, including business, flight instruction, and other personal activities. Air carriers include both scheduled and non-scheduled flights.

Alternative Fuels: Methanol, denatured ethanol, and other alcohols, mixtures containing 85 percent or more (or such other percentage, but not less than 70 percent) by volume of methanol, denatured ethanol, and other alcohols with gasoline or other fuels; natural gas; liquefied petroleum gas; hydrogen; coal-derived liquid fuels; fuels (other than alcohol) derived from biological materials; and electricity, including electricity from solar energy.

Automobiles: Includes household, government, and commercial cars. The RTECS includes company vehicles if used for personal travel in addition to the business usage and the vehicle is ordinarily kept at home.

Buses: Includes commercial, school, and transit buses. It does not include trolley buses.

Combination Trucks: Consists of a power unit (a truck tractor) and one or more trailing units (a semi-trailer or trailer).

Freight Modes: Includes truck, air, marine, rail, and pipeline freight modes. It does not include gas and water pipeline.

Heavy-Duty Vehicles: Combination of all high passenger occupancy modes of transportation, including buses, trains, general aviation, and air carriers.

Light-Duty Vehicles: Include automobiles, motorcycles, and light trucks.

Light Trucks: All single unit two-axle, four-tire trucks, including pickup trucks, sports utility vehicles, vans, motor homes, etc. This is the Department of Transportation definition. The Energy Information defined light truck as all trucks weighing 8,500 pounds or less.

Marine Freight: Freight transported over rivers, canals, the Great Lakes, and domestic ocean waterways.

Other Single-Unit Truck: A motor vehicle consisting primarily of a single motorized device with more than two axles or more than four tires.

Passenger-Miles Traveled: The total distance traveled by all passengers. It is calculated as the product of the occupancy rate in vehicles and the vehicle miles traveled.

Passenger Modes: Includes Light-Duty Vehicles and Heavy-Duty Vehicles. See Light-Duty Vehicles and Heavy-Duty Vehicles in this section of the glossary.

Passenger Rail: Includes short- and long-distance passenger rail, commuter rail, and light and heavy rail. Heavy rail is electric transit vehicle with capacity for heavy "volume" traffic. It is more generically referred to as subway. Light rail is a type of electric transit railway with a light-volume capacity, with generic names like "streetcars," "trolley cars," and "tramways."

Pipeline Freight: Refers to freight carried through pipelines, including natural gas, crude oil, and petroleum products (excluding water). Energy is consumed by various electrical components of the pipeline, including, valves, other, appurtenances attaches to the pipe, compressor units, metering stations, regulator stations, delivery stations, holders and fabricated assemblies. This report presents only oil pipeline freight.

Rail Freight: Refers to intercity freight movement by trains.

Site Energy Consumption: This includes gasoline, distillate fuel oil, liquefied petroleum gas, jet fuel, residual oil, natural gas, and electricity converted to their Btu equivalent. Primary energy consumption also includes electrical losses.

Site Energy Consumption Conversion: Electricity consumption is reported for pipelines and passenger rail in the Oak Ridge National Laboratory Transportation Energy Data Book. The primary electricity volumes were converted to site electricity applying conversion factors. See Appendix A for the methodology.

Sport-Utility Vehicle: Includes light trucks that are similar to Jeeps. Other common terms for these vehicles are sport, special purpose, utility, or off-the-road vehicles. They may have a four- or two-wheel drive.

Ton Miles: The product of the distance freight is hauled, measured in miles, and the weight of the cargo being hauled, measured in tons. Thus, moving one ton one mile generates one ton mile.

Truck Freight: This is freight carried by single-unit, non-two-axle, four-tire trucks (Other single unit trucks) and combination trucks.

Two-axle, four-tire trucks: A motor vehicle consisting primarily of single motorized device with two axles and four tires.

Vehicle-Miles Traveled: One vehicle traveling a distance of one mile. Total vehicle miles is the total mileage traveled by all vehicles.

Industrial Sector

Byproduct Fuels: Secondary or additional products resulting from the feedstock use of energy or the processing of nonenergy materials. For examples, the more common byproducts of coke ovens are coal gas, tar, and a mixture of benzene, toluene, and xylene (BTX). Byproduct fuels are produced by the use of both energy and nonenergy raw material input, but they appear differently on various measures of energy consumption, depending on which one is being considered. For instance, total input for heat, power, and electricity generation include both types of byproduct fuels. In order to avoid double counting of primary energy, however, primary energy consumption for all purposes does not include byproduct fuel resulting from the use of other energy, but includes those resulting from the use of nonenergy sources as raw material input.

Capacity-Utilization Rate: Equals the seasonally adjusted index of industrial production divided by a capacity index (sustainable practical capacity, i.e., the greatest level of output a plant can maintain within a realistic work schedule). The Federal Reserve Board weights the capacity indexes by value-added proportions. This methodology is described in Appendix A.

Feedstock Energy Consumption: Includes all energy sources consumed as a raw material, and it is definitionally equivalent to total primary consumption of energy for nonfuel purposes described in the Manufacturing Energy Consumption Survey (MECS).

Gross Output: Gross output equals shipments, minus cost of resale, plus changes in business inventories, coverage adjustment, commodity taxes, and new force account construction (value of construction undertaken with own labor, capital, etc.). All components are deflated to 1987 dollars. The Bureau of Economic Analysis considers this to be the most comprehensive measure of manufacturing production.

Gross Product Originating (GPO): The attribution of gross domestic product to industries or sectors of origin, as provided by the National Income and Product Accounts of the Bureau of Economic Analysis. GPO is compiled by summing income components--wages and salaries, capital, profits, etc.--and corresponds in concept to value added. GPO deflators are used to convert current dollar-denominated value added into 1987 constant dollars.

High-Energy Consumers: Consists of the major manufacturing groups Food and Kindred Products, Paper and Allied Products, Chemicals and Allied Products, Petroleum and Coal Products, Stone, Clay and Glass Products, and Primary Metal Industries. These firms convert raw materials into finished goods primarily by chemical (and not by physical) means. Heat is essential to their production, and steam provides much of the heat. Natural gas and byproduct and waste fuels are the largest sources of energy for this group.

High-Value Added Consumers: Producers of high value-added transportation vehicles, industrial machinery, electrical equipment, instruments, and miscellaneous equipment. The primary end uses are motor-driven physical conversion of materials (cutting, forming, assembly) and heat treating, drying and bonding. Natural gas is the principal energy source for these firms.

Industrial Production: The Federal Reserve Board calculates this index by compiling indices of physical output from a variety of agencies and trade groups, weighting each index by the Census' value added, and adding it to the cost of materials. When physical measures are not available, the Federal Reserve Board uses the number of production workers or amount of electricity consumed as the basis for the index. To convert industrial production into dollars, multiply by the "real value added" estimate used by the Federal Reserve Board.

Industrial Sector: As defined by EIA, Comprises manufacturing industries, which make up the largest part of the sector, along with mining, construction, agriculture, fisheries, and forestry. Establishments in the sector range from steel mills and small farms to companies assembling electronic components. The SIC codes 20 through 39 are used to classify establishments as industrial. A subdivision of U.S. economic activity defined by EIA to include manufacturing, construction, mining, agriculture, fishing, and forestry (nonmanufacturing) establishments.

Inventories: Year-end inventories at cost or market value, deflated to 1987 constant dollars using value of shipments implicit price deflators reported by Bureau of Economic Analysis.

Low-Energy Consumers: This group is the smallest energy consuming sector and represents a combination of end use requirements. Motor drive is one of the key end uses. Included in this group are tobacco firms, textile mills, lumber mills, rubber and plastics plants, printing and publishing operations, and furniture, apparel, and leather makers.

Major Industry Groups: Two-digit SIC industries, 1-39.

Manufacturing Establishment: An economic unit at a single physical location where mechanical or chemical transformation of materials or substances into new products are performed.

Manufacturing Sector: One of 10 fields of economic activity defined by the Standard Industrial Classification Manual, including two-digit SIC industries 20-39. It includes all establishments engaged in the mechanical or chemical transformation of materials or substances into new products. The establishments in the manufacturing sector constitute the universe for MECS.

Total Consumption of Energy for All Purposes: This measure includes offsite-produced energy, feedstocks energy, and onsite byproduct fuels resulting from the use of a nonenergy materials as feedstocks. It excludes electricity losses, as well as byproduct fuels resulting from the use of energy sources as raw materials.

Nonmanufacturing: Includes agriculture, construction, mining, and resource extraction.

Offsite-Produced Energy for Heat, Power and Electricity Generation: This measure of energy consumption, which is equivalent to purchased energy includes energy produced off-site and consumed onsite. It excludes energy produced and consumed onsite, energy used as raw material input, and electricity losses.

Standard Industrial Classification (SIC): A classification scheme developed by the Office of Management and Budget that categorizes establishments into groups with similar economic activities.

Total Inputs of Energy for Heat, Power, and Electricity Generation: This measure of energy consumption includes offsite-produced energy and byproduct fuels resulting from the use of both energy and nonenergy materials as feedstocks. However, it excludes feedstocks and electricity losses. Reported in trillion or quadrillion Btu and referred to as Inputs of Energy in this report.

Value Added: For the manufacturing and mining sectors, it is a measure of activity derived by subtracting the cost of materials, supplies, containers, purchased fuel and electricity, and contract work from the value of shipments (products manufactured or mined plus receipts for services rendered). This calculation is adjusted by adding the value added by merchandising (mark-up) and the net change in finished goods and work-in-progress inventories. For industries in which value of production is collected instead of value of shipments, value added is adjusted by the change in work-in-progress inventories. Deflated to 1987 constant dollars using GPO deflator.

Value of Production: Calculated as the value of shipments plus inventory change during the year (subtract prior year-end from current year-end inventories) in constant 1987 dollars.

Value of Shipments: Received or receivable net selling values (exclusive of freight and taxes) of all primary and secondary products shipped, as well as all miscellaneous receipts for contract work performed for others, installation and repair, sales of scrap, and sales of products bought and resold without further processing. Deflated to constant 1987 dollars using GPO deflators.

Structurally-Adjusted Estimates: Aggregate energy-intensity changes in the manufacturing sector, from which energy efficiency changes may be inferred, include real efficiency changes, changes due to structural shifts in the economy, and interaction effects. Separation of structural effects from manufacturing energy-intensity is achieved by characterizing the economy in such a way that changing composition of the manufacturing sector is measured by changes in the relative output (or changes in the share of output).

It must be emphasized that the extent to which structural shifts can be eliminated from intensity measurement depends on the level of disaggregation. For instance, disaggregation at the four-digit SIC level would yield a better result than that at the three-digit SIC level, while disaggregation at the three-digit SIC level would yield a better result than that at the two-digit level.

U.S. Economy

Energy Source: Any substance that supplies heat or power, e.g., petroleum, natural gas, coal, renewable energy, and electricity, including the use of a fuel as a non-energy feedstock.

Fossil Fuel: Any naturally occurring organic fuel, such as petroleum, coal, and natural gas.

Gross Generation: The total amount of electric energy produced by the generating units at a generating station(s), measured at the generator terminals.

Gross Inputs: The heat value (Btu) of the energy sources used to generate electricity, measured at the generator terminals, including energy used at the generating station.

Net Generation: Gross generation less megawatt hours consumed out of gross generation for station use or auxiliary equipment the electric energy consumed at the generating station for station use.

Nonutility Generator: A corporation, person agency, authority, or other legal entity or instrumentality that owns electric generating capacity and is not an electric utility. Include qualifying cogenerators and small power producers, and other nonutility power producers without a designated franchised service area.

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File Last Modified: August 17, 2004