1. How the Survey Was Conducted

Introduction
 
The Commercial Buildings Energy Consumption Survey (CBECS) is conducted by the Energy Information Administration (EIA) to provide basic statistical information on energy consumption and expenditures for U.S. commercial buildings and data on energy-related characteristics of these buildings. The survey is based upon a sample of commercial buildings selected according to the sample design requirements described below. A “building” as opposed to an “establishment” is the basic unit for the CBECS because a building is the energy-consuming unit.
 
The CBECS is conducted in two major data-collection stages: a Building Characteristics Survey and an Energy Suppliers Survey. The first stage, the Building Characteristics Survey, collects information about selected commercial buildings through voluntary personal interviews with the buildings’ owners, managers, or tenants. In 1995, the data were collected by using Computer-Assisted Personal Interviewing (CAPI) techniques. An authorization form signed by the respondent is used to secure the release of the building’s energy consumption and expenditures records from the energy supplier.
 
The Energy Suppliers Survey, the second data-collection stage, obtains data about the building’s actual consumption of energy and associated expenditures for that energy from records maintained by energy suppliers. The information is obtained by means of a mail survey conducted under EIA’s mandatory data collection authority. Additionally, the CBECS asks energy suppliers about any demand-side management programs they may have provided to the building. Under EIA’s direction, a survey research firm conducts both the personal interviews for the Building Characteristics Survey and the mail survey for the Energy Suppliers Survey.

Confidentiality of Information
 
EIA does not receive or take possession of the names or addresses of individual respondents or any other individually identifiable energy data that could be specifically linked with an individual sample building or building respondent. All names and addresses are maintained by the survey contractor for survey verification purposes only. Geographic identifiers and NOAA Weather Division identifiers are not included on any data files delivered to EIA. Geographic location information is provided to EIA at the Census division level. In addition, building characteristics, such as number of floors, building square footage, and number of workers in the building, that could potentially identify a particular responding building, are masked on data files provided to EIA, as well as on all public-use data files.

Target Population
 
The target population for CBECS consists of all commercial buildings in the United States larger than 1,000 square feet, with the exception of commercial buildings located on manufacturing sites. To be eligible for the survey, a building had to satisfy three criteria: (1) it had to meet the survey’s definition of a building, (2) it had to be used primarily for some commercial purpose, and (3) it had to measure 1,001 square feet or more. A building is defined by CBECS as a structure totally enclosed by walls that extend from the foundation to the roof and is intended for human access. To be used primarily for some commercial purpose, the building must have more than 50 percent of its floorspace devoted to activities that are neither residential, industrial, nor agricultural. The 1995 CBECS estimated that there were 4,579 thousand buildings in the target population.

 
Sample Design
 
The sample design for the CBECS is a multistage area probability cluster sample design supplemented by a list sample of “large” buildings, recently constructed buildings, and “special” buildings (Federal Government buildings and post offices, hospitals, colleges, and universities). The area sample portion of the design is a sample from the broad spectrum of commercial buildings. The supplemental list sample provides an oversample of “large” buildings and “special” buildings. Similarly, for recently constructed buildings, the area sample is used to provide a sample from the broad spectrum of new buildings and the supplemental list sample provides an oversample of “large” new buildings.
 
Multistage Area Probability Sample: The area component of the CBECS sample uses a four-stage cluster sampling design that selects primary sampling units (PSU’s), secondary sampling units (SSU’s), segments, and, ultimately, buildings. The first three of these stages involve sampling progressively smaller geographic areas. For the 1995 CBECS, the same PSU’s, SSU’s, and segments that were selected for the 1986 CBECS were reused. For the fourth stage of sampling, the 1995 selection of buildings was executed by using procedures to update the 1986 CBECS building lists to include new construction in the sampled segments.  

Supplementary List Sample from Lists of Large and Specialized Buildings: To ensure adequate coverage of buildings that are significant energy users, the multistage area probability sample is supplemented within each selected PSU by a sample from a list of “large” buildings (buildings over 250,000 square feet) or facilities. In addition, to improve the precision of energy consumption estimates for certain types of buildings, a supplementary sample is drawn from several lists of special buildings. These list frame files differ from the area segment listings in that the list files are primarily facility or construction-project based as opposed to building based.

Sample Selected
 
The goal of the 1995 CBECS sampling procedures (both the area sample and the supplemental list sample) was to achieve completed interviews for 5,500 buildings — 4,450 buildings from the area sample and 1,050 buildings from the supplemental list sample. In order to achieve the goal for number of respondents, a sample of 8,074 potential cases was selected, consisting of 6,633 buildings from the area sample frame and 1,441 buildings from the supplemental list sample frames consisting of large buildings and special buildings. Of these 8,074 buildings, 6,590 buildings were found eligible for interviewing. The three primary eligibility criteria, building definition, building use, and building size are described in the “Determining Building Eligibility” section below. Other reasons for sample building listings to be classified as ineligible included duplication of buildings, demolished buildings, buildings under construction, or commercial buildings on industrial facilities.

 
Response Rates
 
Of the 6,590 eligible buildings, interviews were completed for 87.5 percent, or 5,766 buildings (4,728 buildings from the area sample and 1,038 buildings from the supplemental list sample). Of the 5,766 CBECS respondents, 5,668 reported some energy use in the building. For 92.6 percent, or 5,250, of these buildings, an authorization form was obtained which allowed the survey contractor to contact the energy suppliers for release of the energy billing data for the building.
 
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Continue to “Building Characteristics Survey”
 

 
Specific questions on these topics may be directed to:
 
Joelle Michaels
joelle.michaels@eia.doe.gov
CBECS Manager
Phone: (202) 586-8952
FAX: (202) 586-0018

URL: http://www.eia.doe.gov/cbecs/tech_survey_intro.html

File last modified November 16, 1999