Because of the sampling error associated with the estimates, the apparent differences between the estimates for either number of buildings or amount of floorspace for the different survey years are not statistically significant. All consumption data referred to in this report is site energy, unless otherwise indicated. The greatest consumption for any energy source was 2.6 quadrillion Btu for electricity, followed by 1.9 quadrillion Btu for natural gas. Expenditures per unit of site electricity were 21.7 dollars per million Btu and expenditures per unit of primary electricity were 7.2 dollars per million Btu. For natural gas, expenditures per unit of energy were 4.6 dollars per million Btu, with 5.8 dollars per million Btu for district heat and 5.0 dollars per million Btu for fuel oil.
Energy intensity is the amount of energy consumed per unit of service or activity.
For the commercial buildings sector, useful indicators of energy intensity are consumption per square foot, consumption per hour of operation, or consumption per worker. The most commonly-used measure of commercial energy intensity is consumption per square foot. Two measures of floorspace can be used, total floorspace and conditional floorspace, which further defines the floorspace. Neither total consumption or total intensities were statistically significantly different between the three survey years. There were no significant differences in consumption for any major energy source for the three years, but there was a significant decrease in fuel oil intensity from 1989 to 1995.