After determining buildings built to the 2010 version of ANSI/ASHRAE/IESNA Standard 90.1, Energy Standard for Buildings Except Low-Rise Residential Buildings, consume significantly less energy—18.2 percent source and 18.5 percent site—than buildings built to the 2007 version, the U.S. Department of Energy (DOE) issued a ruling making the 2010 version the commercial-building reference standard for state building energy codes.

The DOE attributes the greater energy savings to improvements related to lighting, daylighting, controls, and building envelope; better mechanical systems; and application to more systems.

Under the federal Energy Conservation and Production Act, states are required to certify by Oct. 18, 2013, that they have updated the energy-efficiency provisions of their commercial-building code to meet or exceed Standard 90.1-2010.

The ruling comes on the heels of a July announcement establishing Standard 90.1-2007 as the commercial-building reference standard for state building energy codes. The DOE noted that because the determination concerning Standard 90.1-2010 was published prior to the two-year deadline states have to demonstrate their energy code meets or exceeds the stringency of the 2007 standard, states can file just one certification to address both determinations.