Residential and commercial codes require increases in building efficiency, and can help drive the transition to a more efficient economy. Recent and significant changes to the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) 90.1-2010 and the International Energy Conservation Code (IECC) 2012 require decreases of 9–38% and 12–15% in energy use from a 1975 baseline, respectively.
U.S. Department of Energy, Building Energy Codes. 2010. Enhancing Energy Efficiency Nationwide. April. link