U.S. Energy Information Administration - EIA - Independent Statistics and Analysis
Commercial Buildings Energy Consumption Survey (CBECS)
Data from the 1992 Commercial Buildings Energy Consumption Survey (CBECS) are presented in three groups of detailed tables:
- Buildings characteristics tables—number of buildings and amount of floorspace for major building characteristics.
- Energy consumption and expenditures tables—energy consumption and expenditures for major energy sources.
- Energy end-use tables—total, electricity and natural gas consumption and energy intensities for nine specific end-uses.
Released: Nov 1999
The first set of detailed tables for the 1992 CBECS, Tables A1 through A70, contain the number of buildings and amount of floorspace for major building characteristics. Tables A2 through A28 address location, building size, year constructed, number of workers, hours of operation, types of occupancy, multibuilding facilities, and special space functions. Tables A29 through A43 contain data about the energy sources used for all end uses and for specific major end uses. Tables A44 through A46 contain data about percent of floorspace heated, cooled, and lit. Tables A47 through A56 contain data on energy-using equipment types, and Tables A57 through A67 contain data on conservation and energy management features. The last group of building characteristics tables include special data tabulations. Table A1 is a summary table, Table A68 provides total number of buildings and amount of floorspace for all principal building activities, and Tables A69 and A70 contain data on energy sources used for selected energy uses.
The second set of tables consists of energy consumption and expenditures Tables 3.1 through 3.49, which present detailed energy consumption and expenditure data for buildings in the commercial sector. These tables are grouped into major fuel tables (Tables 3.1 through 3.13) and specific energy source tables. The specific energy source tables consist of Tables 3.14 through 3.29 for electricity, Tables 3.30 through 3.40 for natural gas, Tables 3.41 through 3.45 for fuel oil, and Tables 3.46 and 3.47 for district heat.
The third set of tables consists of energy end-use Tables 1 through 6, which contain estimates of the amount of natural gas and electricity that is consumed for nine specific end uses: space heating, cooling, ventilation, water heating, lighting, cooking, refrigeration, office equipment, and other.
The column categories most commonly classify data by consumption and expenditures, though several other classifications are also given. The following terms, listed in alphabetical order, attempt to explain some of the column categories that may require clarification.
Conditional Energy Intensity—The amount of electricity, natural gas, fuel oil, or district heat used per square foot in buildings using the specified energy source. For example, in Table 3.16, data in the row labeled "Electricity" under "Energy Sources" and in the column labeled "Northeast" under "Electricity Energy Intensity" would read: "Buildings in the Northeast that used electricity as an energy source used 9.3 kilowatthours of electricity per square foot."
Demand-Metered Buildings—Buildings that have meters to measure peak demand (in addition to total consumption) during a billing period. Peak demand is usually metered only for electricity.
Distribution of Building-Level Intensities—The amount of energy used per square foot, divided into three percentiles: 25th, median, and 75th. In Table 3.15, for example, the row labeled "Education" under "Principal Building Activity" in the columns under "Distribution of Building-Level Intensities" would read: "In 1992, 25 percent of U.S. education buildings used 4.0 kilowatthours per square foot or less, while 75 percent of the buildings used more than 4.0 kilowatthours of electricity per square foot."
Electricity—Site electricity. (See "site electricity" and "primary electricity" in this listing.)
Energy Intensity—Usually defined as "gross energy intensity" or "conditional energy intensity" in title of table. If table title does not specify, "energy intensity" is to be defined as "conditional energy intensity."
Floorspace—The enclosed area in a building; the sum of the floorspace in all buildings in a category.
Gross Energy Intensity—The ratio of the total amount of energy consumed by a group of buildings to the total floorspace of those buildings, including buildings and floorspace where the energy source is not used. For example, in Table 3.7, data in the row category "Education" under "Principal Building Activity" and in the column category of "Northeast" would read: "Education buildings in the Northeast consumed 87.1 thousand Btu per square foot."
Major Fuel—Major energy sources: electricity, natural gas, fuel oil, and district heat (district steam and district hot water). Although electricity is technically not a fuel, "Major Fuel," rather than "Major Energy Source," was retained as the title of this category to facilitate comparison of 1992 and 1989 CBECS data.
Primary Electricity—Site electricity plus the conversion losses in the electric generation process at the utility plant. Most of the tables present statistics for site consumption alone, but Tables 3.2 and 3.14 also provide consumption statistics for primary electricity.
Site Electricity—The amount of electricity delivered to the commercial building. This amount excludes conversion losses in the electric generation process at the utility plant. (See "primary electricity" in this listing.) Most of the tables in this section provide statistics for site electricity alone (not on primary electricity). When the term "electricity" is used, the reference is to site electricity.
Total of Major Fuels—The sum of site electricity, natural gas, fuel oil, and district heat. Statistics in this column exclude data from the column "Primary Electricity."
The row categories classify data by specific features, such as energy source or end use. Data in the row categories relate to the buildings having such a feature, not to the feature. For example, in Table 3.4, the data in the "Major Fuels" column and the row category "Buildings with A/C" is to be read as "Buildings with air conditioning consumed 5,345 trillion Btu of the major fuels." The table contains no data on the energy consumption for air conditioning specifically. Although the row categories and subcategories are similar in all the tables, the specific-fuel tables provide more categories of data than are presented in the major fuel tables. For example, the electricity tables provide data on buildings containing refrigeration and lighting equipment and computers.
Below are explanations of some of the row categories, in a consumption or expenditures column, that may require clarification, listed in the order in which they occur in the tables.
All Buildings—Consumption or expenditures for roofed and walled structures whose principal activities are nonresidential, nonagricultural, and nonindustrial and which are larger than one thousand square feet (roughly twice the size of a two-car garage).
Principal Building Activity—Consumption or expenditures for buildings grouped by the activity that occupies the most floorspace in the buildings. Some building types are combined in the tables. For example, inpatient and outpatient health care facilities were combined as "health care buildings," and refrigerated and nonrefrigerated warehouses were combined as "warehouses," and skilled nursing buildings were included in "lodging." The category "assembly" in the 1989 CBECS was broken into "public assembly" and "religious worship" for the 1992 CBECS. See "Description of types of buildings" for a full description of the principal building activity categories.
Climate Zone—Consumption or expenditures for commercial buildings located in one of the five U.S. climate zones, based on the average number of cooling degree-days (CDD) and heating degree-days (HDD) in a 45-year period (1931-1975). See "U.S. Climate Zones map" for a map that shows the five U.S. climate zones.
Census Region and Division—Consumption or expenditures for commercial buildings located in one of the nine divisions within four regions as defined by the U.S. Bureau of Census. See "Census Regions and Divisions map" for a map that shows the four Census regions and nine Census divisions.
Energy Sources—Consumption or expenditures for buildings using a specific type of energy (electricity, natural gas, fuel oil, district heat [district steam and district hot water], district chilled water, propane, and any other type of energy [wood, coal, active solar, and photovoltaic cells]). The tables contain consumption data based on billing information obtained from energy suppliers, for the first four sources only. Estimates of the amount of wood burned in buildings were obtained during the personal interviews with building respondents. No consumption data were collected for propane, coal, solar energy, or other renewable sources because such a collection effort would not be feasible.
Energy End Uses—Consumption or expenditures in buildings that had specific end uses (heating, air conditioning, water heating, cooking, and manufacturing), not the amount of energy consumption or expenditures for a particular end use.
Energy-Related Space Functions—Consumption or expenditures in buildings that had space for commercial food preparation or computer use, space using special ventilation, or space where activities requiring large amounts of hot water took place. The tables contain no data on the amount of energy consumption or expenditures for these specific activities.
Space-Heating Energy Sources—Consumption or expenditures in buildings using at least one of the major fuels, propane, wood, or any other energy source for space heating. (In some tables, this category is subdivided into "Main and Secondary Energy Sources.") The tables contain no data on the amount of energy consumption or expenditures for space heating specifically.
Main Space-Heating Energy Source—Consumption or expenditures in buildings using a specific energy source to heat most of the square footage in the building most of the time. The tables contain no data on the amount of energy consumption or expenditures for space heating specifically.
Replacement Energy Source for Main Heating—Consumption or expenditures in buildings using a replacement energy source (a heating source to which a building could switch within one week without major modifications to the main heating equipment, without substantially reducing the area heated, and without substantially reducing the temperature maintained in the heated area). The tables contain no data on the amount of energy consumption or expenditures for replacement heating specifically.
Cooling Energy Source—Consumption or expenditures in buildings using electricity, natural gas, or district chilled water for cooling. The tables contain no data on the amount of energy consumption or expenditures for cooling specifically.
Water-Heating Energy Source—Consumption or expenditures in buildings using one of the major fuels or propane for water heating. The tables contain no data on the amount of energy consumption or expenditures for water heating specifically.
Cooking Energy Source—Consumption or expenditures in buildings using electricity, natural gas, or propane for cooking. The tables contain no data on the amount of energy consumption or expenditures for cooking specifically.
Manufacturing Energy Sources—Consumption or expenditures in buildings using electricity, natural gas, or other energy source for manufacturing. The tables contain no data on the amount of energy consumption or expenditures for manufacturing specifically.
Heating Equipment—Consumption or expenditures in buildings that had at least one type of heating equipment. The tables contain no data on the amount of energy consumption or expenditures for the specific types of heating equipment.
Heating Distribution Equipment—Consumption or expenditures in buildings that had at least one type of heating-distribution equipment. The tables contain no data on the amount of energy consumption or expenditures for the specific types of heating-distribution equipment.
Cooling Equipment—Consumption or expenditures in buildings that had at least one type of cooling equipment. The tables contain no data on the amount of energy consumption or expenditures for the specific types of cooling equipment.
Cooling Distribution Equipment—Consumption or expenditures in buildings that had at least one type of cooling-distribution equipment. The tables contain no data on the amount of energy consumption or expenditures for the specific types of cooling-distribution equipment.
Water-Heating Equipment—Consumption or expenditures in buildings that had a centralized system, a distributed system, or both. The tables contain no data on the amount of energy consumption or expenditures for the specific types of water-heating equipment.
Energy Conservation Features—Consumption or expenditures in buildings that had any feature designed to reduce the amount of energy consumed by the building because of its:
Shell, such as insulation, storm windows, or tinted glass;More detailed data are also given for buildings having at least one of the specific energy-conservation features.
Heating, ventilation, and air conditioning (HVAC) equipment, such as a variable air-volume system, economizer cycle, or regular maintenance; or
Lighting, such as manual dimmer switches, specular reflectors, or occupancy sensors.
Energy Management Practices—Consumption or expenditures in buildings with at least one energy-management practice, including having an energy management and control system, participating in a demand-side management program, having had an energy audit, or employing a building energy manager.
Released: Nov 1999
The CBECS estimates of buildings and floorspace always differ from the true population values because the CBECS estimates are based on data collected from a randomly chosen subset of the entire commercial building population. One source of the difference between the estimated values and the actual values is sampling error. Sampling error is the random difference that occurs between the survey estimate and the population value because the survey estimate is calculated from a randomly chosen subset of the entire population. The sampling error, if averaged over all possible samples, would be zero, but since there is only one sample for each CBECS, the sampling error is nonzero and unknown for the particular sample chosen. However, the sample design permits sampling errors to be estimated.
The standard error is a measure of the reliability or precision of the survey statistic. The value for the standard error can be used to construct confidence intervals and to perform hypothesis tests by standard statistical methods. Relative Standard Error (RSE) is defined as the standard error (square root of the variance) of a survey estimate, divided by the survey estimate and multiplied by 100. The 95-percent confidence range for a given survey estimate can be determined with the RSE. To calculate the 95-percent confidence range:
- Divide the RSE by 100 and multiply by the survey estimate in the table to determine the standard error.
- Multiply the standard error by 1.96 to determine the confidence error.
The survey estimate plus or minus the confidence error is the 95-percent confidence range. For example, the estimate for total floorspace in all commercial buildings in the 1992 CBECS is 67,876 million square feet and the estimate's RSE is 3.7 percent. The standard error is (3.7Ã·100)Ã—(67,876 million square feet) or 2,511 million square feet. The 95-percent confidence error is (1.96)Ã—(2,511 million square feet), or 4,922 million square feet. Therefore, with 95 percent confidence, the true amount of floorspace in commercial buildings in the United States in 1992 was 67,876 (Â± 4,922) million square feet or, stated another way, the range was from 62,954 to 72,798 million square feet.
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 is computed as:
where S is the standard error, x1 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.
For example, in 1992, mercantile and service buildings consumed an estimated 381 trillion Btu of natural gas, while health care buildings consumed an estimated 189 trillion Btu, for an estimated difference of 192 trillion Btu. The standard error for the 381 trillion Btu estimate (x1) is 60.96, and the standard error for the 189 trillion Btu estimate (x2) is 33.64 and
Multiplying 69.63 by 1.96 yields 136.5. Since 136.5 is less than 192, the difference between the two estimates is statistically significant.
|Data Item||Number of Buildings
|Buildings Characteristics Tables (70 tables, 230 pages, 1.39 MB)|
|Location: (27 pages, 176 KB)|
|Structure: (31 pages, 195 KB)|
|Building Use: (47 pages, 264 KB)|
|Number of Workers||A17||A18|
|Weekly Operating Hours||A19||A20|
|Special Space Functions||A26||A27|
|Additional Operating Hours||A28||A28|
|Energy Sources and End Use: (36 pages, 225 KB)|
|Energy End Uses||A33||A33|
|Space-Heating Energy Sources||A36||A37|
|Primary Space-Heating Fuel||A38||A39|
|Cooling Energy Sources||A40||A40|
|Water-Heating Energy Sources||A41||A42|
|Cooking Energy Sources||A43||A43|
|End-Use Percentage: (32 pages, 90 KB)|
|Percent of Floorspace Heated||A44||A44|
|Percent of Floorspace Cooled||A45||A45|
|Percent of Floorspace Lit||A46||A46|
|End-Use Equipment: (32 pages, 198 KB)|
|Conservation: (34 pages, 200 KB)|
|Energy Conservation Features||A57||A57|
|Reduction in Equipment Use||A62||A63|
|Ligthing DSM Participation||A64||A65|
|HVAC DSM Participation||A66||A67|
|Special Tabulations: (10 pages, 63 KB)|
|Principal Building Activity||A68||A68|
|Energy Sources Used for Particular End-Use||A69||A70|
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