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U.S. Department of Energy Energy Efficiency and Renewable Energy

Energy Intensity Indicators: Commercial Buildings Total Energy Consumption

The Figure C1 below reports energy use based on total energy consumption, increases in floor space, the weather effect, and energy intensity, as index numbers, over the period 1985 to 2002.

  • Activity: Estimated total floor space in commercial buildings grew slightly more than 35% from 1985 to 2004, with particularly rapid growth in the latter part of the 1990s.
  • Energy Use: Commercial energy consumption, measured as total consumption (i.e., including electricity losses; see Terminology), has increased in every year since 1985, with the single exception of 2003. By 2004, total commercial energy consumption was nearly 50% higher than in 1985.
  • Energy Intensity Index: Commercial building sector energy intensity increased by 12% over the 1985-2004 period.
  • Changes due to factors unrelated to efficiency improvements: Commercial buildings are sensitive to weather, although not to the same degree as residential buildings. The chart below shows the estimated weather factor (as an index), based upon heating and cooling degree-days by census region. The years 1990 and 1992 stand out; calendar year 1990 contained very warm winter weather and 1992 was an especially cool summer. The decreases in intensity observed in 1991 and since 2001 are primarily the result of weak economic conditions in the economy as a whole. In these periods, vacancy rates of commercial office and retail space increase and the utilization of occupied space falls.
A chart shows four lines representing energy consumption, floorspace, a weather-adjusted intensity index, and weather factor for the years 1985 to 2004. An index with 1985 equal to 1.0 is plotted on the vertical axis; years are plotted on the horizontal axis. The top line, energy consumption, is a slightly wavy line with no dips that rises from 1.0 in 1985 to 1.5 in 2004. The second line from the top, floorspace, is a fairly straight line, rising from 1.0 to 1.35 during the period. The third line, intensity index, is a gently undulating line that rises to 1.12 in 2004. The bottom line, weather factor, is nearly a straight horizontal line at 1.0, with very slight dips in 1990, 1998, 2001, and 2004, and a more pronounced dip to 0.98 in 1992.

Figure C1 . Commercial Energy Use, Activity, Weather, and Intensity, 1985-2004

Figure C2 shows electricity consumption per square foot of floor space in five building types, for all buildings, and for the residue of other types lumped into an "other" category, for five years when the Commercial Energy Consumption Survey was conducted. In some cases the trend, to the extent there is one, is upward (Education, Health Care and Assembly buildings), in others downward (Offices and Retail/Service buildings).

A vertical bar chart with seven sets of five bars shows energy consumption for seven types of commercial buildings for the years 1983, 1986, 1989, 1992, and 1995. Thousand Btu per square foot is plotted on the vertical axis. The first set of bars on the left, Education, rises from 26 to 29 during the period, with a slight dip in 1986. The second set of bars from the left, Office, varies from the low to upper 60s, except for dipping to 58 in 1992; it rises to 64 in 1995. The third set of bars, Retail/Service, is around the low 40s, except for dipping to 37 in 1992; it rises to 40 in 1995. The fourth set of bars, Health Care, has the tallest bars and show the largest variation, rising from 64 and 62 in 1983 and 1986 respectively, then rising to the 70s in 1989 and 1992, and reaching 91 in 1995. The fifth set of bars, Assembly, rises from the low 20s to 30, with a small dip in 1992. The sixth set of bars, Other, jumps around 40, with the tallest bar at 43 in 1983, the shortest at 37 in 1992, and rising to 42 in 1995. The last set of bars, All Buildings, is around the low 40s, except for dipping to 38 in 1992.

Figure C2. Energy Consumption by Building Type, Selected Years
(Source: 1983 through 1995 CBECS)

The sorting out of the effect of other explanatory factors, such as building type, is a work in progress. (Current estimates were based upon the Commercial Building Energy Consumption Survey (CBECS), a survey of commercial buildings conducted periodically by the Energy Information Administration). At this stage, however, we are not yet able to quantify many explanatory factors in any comprehensive fashion for the commercial sector system of indicators.