Energy Intensity Indicators: Residential Buildings Delivered Energy
Figure R1, below, reports residential energy consumption measured as delivered energy, increases in households, increases in house size, a combined structural component that captures many of the "other explanatory factors," and energy intensity, as index numbers, over the period 1985 to 2004.
- Activity: The number of households, the activity measure for this sector, has increased by about 28% since 1985.
- Energy Use: Residential energy consumption, measured as delivered consumption (i.e., excluding electricity losses), has increased 18% since 1985, compared to a 28% increase in the number of households over the same period. As shown in the graphic below, consumption declined in 1990, 1997, 1998 and 2001, years of mild winter weather.
- Energy Intensity Index: The residential energy intensity index is based upon a ratio of energy use per square foot of floor area. The intensity index has generally trended downward since 1985, with the greatest declines observed since the early part of the 1990s. By 2004 energy intensity had declined by 18% compared to 1985.
- Changes due to factors unrelated to efficiency improvements: Since 1993 several structural effects have moderated energy consumption in the residential sector. In 2004 these factors combined to reduce energy use by about 7% as compared to 1985. Long-term shifts in the geographic distribution of households (e.g. north to south) and the types of housing units (e.g. single-family vs. multi-family) were responsible for nearly a 3% reduction in delivered energy in 2004 compared to 1985. Weather factors were responsible for the balance of the change.
Figure R2 shows that energy use per household declined substantially over the period 1978-1987, but changed little in the succeeding ten years. While total energy use remained static between 1987 and 1997, heating and cooling energy use declined over this period, while appliance energy use increased enough to offset the declines in other end-uses, thus holding total energy use about the same. (These estimates were based upon the Residential Energy Consumption Survey (RECS), a household survey conducted periodically by the Energy Information Administration).