Commercial Buildings Delivered Energy

Figure C1, below, reports energy use based on delivered energy consumption, increases in floor space, the weather effect, and energy intensity, as index numbers, over the period 1985 to 2004.

Activity: Estimated total floor space in commercial buildings grew rapidly during the economic expansion of the 1990's, with 35% more floor space in 2004 as compared to 1985.
Energy Use: Commercial energy consumption, measured as delivered consumption (i.e., excluding electricity losses), has increased in every year since 1985 with the exceptions of 1990, 1998, 2001, and 2004. By 2004, commercial delivered energy consumption was 36% higher than in 1985.
Energy Intensity Index: On a delivered energy basis, the overall commercial sector energy intensity in 2004 was about the same as in 1985. The declines observed in 1991 and since 2001 are primarily the result of economic recessions. In these periods, vacancy rates of commercial office and retail space increased and the utilization of occupied space fell.
Changes due to factors unrelated to efficiency improvements: Energy use in commercial buildings is sensitive to weather, although not to the same degree as in residential buildings. Figure C1 shows the estimated weather factor (as an index), based upon heating and cooling degree-days by census region. The years 1990, 1992, and 1998 stand out; calendar year 1990 contained very warm winter weather and 1992 was an especially cool summer; 1998 was an especially mild winter.

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 undulating line that rises from 1.0 in 1985 to 1.35 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 or slightly less than 1.0, with slight dips in 1990, 1992 and 1998.

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

Figure C2 shows energy 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. (These 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 these factors in any comprehensive fashion for the system of indicators.

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