From 1950 to 2011, energy intensity in the United States decreased by 58% per real dollar of GDP. Until the 1970s, energy intensity was falling relatively slowly, less than 1% per year. The events surrounding the Arab oil embargo in 1973 were associated with a dramatic rise in energy prices. Before then, energy prices fluctuated only about 3% from year to year.
In 1974, energy prices rose 56% above the previous year, leading to changes in both national policy, such as the establishment of vehicle efficiency standards and consumer attitudes. In addition, the role of energy-intensive industries in the United States declined with continuing structural changes in the economy. Since 1973, energy intensity has declined at a rate closer to 2% per year, although with a few noticeable annual increases. The 2013 Annual Energy Outlook Reference case projects that this average annual decline of 2% will continue through 2040.
Projections to 2040 in the 2013 Annual Energy Outlook show each sector's energy intensity generally declining. Specific drivers of these declines include:
Residential energy intensity, measured as delivered energy used per household, declines about 27% from 2005 to 2040.