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Today in Energy

May 6, 2015

EIA’s CBECS is the nation's only comprehensive survey of commercial buildings

CBECS image, as explained in the article text
Source: U.S. Energy Information Administration

The U.S. Energy Information Administration's Commercial Buildings Energy Consumption Survey (CBECS) is the only nationally representative source of statistical information on energy-related characteristics, consumption, and expenditures for the nation's 5.6 million commercial buildings totaling 87 billion square feet of floor space. Building characteristics information from the 2012 survey is being released in stages through the spring, and consumption and expenditures data will follow later in the year.

The CBECS survey process spans four years, beginning with development of the sample frame and survey questionnaire and ending with release of data to the public. The 2012 CBECS was the tenth survey in the series since 1979. A whole building, as opposed to an individual business or establishment, is the basic unit of analysis for CBECS because the building is the energy-consuming unit. In order to select a statistically valid sample of buildings that will produce accurate information about the commercial buildings population, EIA needs a frame, or list of commercial buildings, from which to select a sample.

Currently there is no existing comprehensive sampling frame of U.S. commercial buildings, so EIA must construct a frame. Most of this frame is called the area frame portion; it comprises all commercial buildings in statistically selected geographic areas. Trained field staff walk or drive through these selected areas and record information about every commercial building.

The other part of the frame (as much as 20%) is called the list frames portion and is constructed from five lists of large buildings, such as hospitals, airports, and federal government buildings, obtained from both public and private sources. This multiframe approach ensures that all types and sizes of commercial buildings have a chance of selection.

Frame accuracy is critical for the CBECS because, unlike the Residential Energy Consumption Survey, which can benchmark results to housing unit estimates from U.S. Census Bureau surveys such as the American Community Survey and the American Housing Survey, the commercial building population totals that come from CBECS are the benchmark—there are no similarly comprehensive surveys for comparison.

CBECS image, as explained in the article text
Source: U.S. Energy Information Administration

After the frame is developed, a sample of buildings is drawn and data collection begins. The data are collected in two stages: the Buildings Survey and the Energy Suppliers Survey.

  • The Buildings Survey collects information about selected commercial buildings through voluntary interviews with the buildings' owners, managers, or tenants. In the 2012 survey, these data were collected using computer-assisted interviews, both in-person and by telephone. About 250 trained interviewers completed this field effort across the United States. During the Buildings Survey, respondents are asked questions about the building size, use of the building, the types of energy-using equipment and conservation measures, the types of energy sources used, and the amount and cost of energy used in the building during calendar year 2012.
  • The Energy Suppliers Survey (ESS) is initiated for buildings whose respondents did not provide consumption and expenditures information, or whose respondents provided information that was not within a range of expected values. The ESS obtains data about the building's actual consumption of and expenditures for energy from records maintained by energy suppliers. These billing data are collected using an online data collection under EIA's mandatory data collection authority.

CBECS data are augmented with geographic information and weather data from the National Oceanic and Atmospheric Administration (NOAA). Daily high and low temperatures from weather stations near each of the buildings surveyed are used to calculate annual heating degree days (HDD) and cooling degree days (CDD), indicators of heating and cooling demand, respectively.

After the consumption data have been collected from the respondents and the energy suppliers, a modeling effort allocates the total consumption into end uses such as heating, cooling, and lighting. During end-use disaggregation, the building survey data (such as operating characteristics and equipment) are used with engineering parameters to produce preliminary estimates. Statistical models then calibrate the engineering results to the reported total energy consumption.

Ultimately, CBECS data are used for many purposes including: benchmarking, building design, policy planning, building code development, market research, and forecasting energy consumption. The results are also a critical input to the Environmental Protection Agency's Energy Star models. The data are made available to the public through tables, reports, and public use data files containing building-level records that allow users to conduct their own analyses. Before releasing public data, information including names, addresses, and other geographic identifiers are removed and certain variables are masked so that individual buildings cannot be identified.

Principal contributor: Joelle Michaels