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.
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).
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.