ANSI/ASHRAE/IESNA Standard 90.1-2004, Energy Standard for Buildings Except Low-Rise Residential Buildings, has been established by the Department of Energy as the commercial building reference standard for state building energy codes starting in 2010.

By December 30, 2010, all states in the United States must certify that their building codes meet or exceed the requirements in ASHRAE/IESNA’s 2004 energy efficiency standard, under a 12/30/08 ruling. If they do not have a code in place at least as stringent as 90.1-2004, they must justify why they can’t comply.

Thirty-seven states complied with the last DOE ruling establishing ASHRAE 90.1-1999 as the national energy standard.

“The quantitative analysis of the energy consumption of buildings built to Standard 90.1-2004, as compared with buildings built to Standard 90.1-1999, indicates national source energy savings of approximately 13.9% of commercial building energy consumption. Site energy savings are estimated to be approximately 11.9%,” according to the ruling published in The Federal Register.

DOE noted that the newer version of the standard contained 13 positive impacts on energy efficiency, several of which are related to lighting:

*Complete replacement of interior lighting power density allowances.
*Revised exterior lighting power density allowances.
*Addition of occupancy sensor requirements for classrooms, meeting and lunch rooms.
*Lower retail sales lighting power allowance.
*New exit sign wattage requirement.

Nearly half of the states (24) currently have an energy code in place at least as stringent as ASHRAE 90.1-2004, meaning 13 states will likely catch up in 2010 and 13 will not comply for various reasons, such as “home rule” state constitutions.

In addition, ASHRAE is working on providing more stringent energy guidance in a proposed standard for high-performance buildings. Being developed in partnership with IESNA and the U.S. Green Building Council, Standard 189.1, Standard for the Design of High-Performance Green Buildings Except Low-Rise Residential Buildings, will provide minimum requirements for the design of high-performance new commercial buildings and major renovation projects, addressing energy efficiency, a building’s impact on the atmosphere, sustainable sites, water use efficiency, materials and resources, and indoor environmental quality.

ASHRAE publishes a revised version of the standard every three years. The latest version is the 2007 version.

I will post a more detailed comparison of the 1999 and 2004 versions of ASHRAE 90.1 soon.