Standard 90.1: Setting the Energy Foundation in Buildings for 35 Years

ATLANTA – While high-performance buildings are the obvious choice in today’s sustainability-focused industry, it was only a short 35 years ago that the first standard for energy efficiency was established, setting the engineering engine of sustainability into motion.

This year marks the 35th anniversary of publication of the ASHRAE/IES energy standard, now known as ANSI/ASHRAE/IES Standard 90.1, Energy Standard for Buildings Except Low-Rise Residential Buildings. Since being developed in response to the energy crisis in the 1970s, Standard 90.1 has become the basis for building codes, and the standard for building design and construction throughout the United States.

The anniversary of the standard was celebrated last week at ASHRAE’s 2010 Annual Conference. For more information about the standard, visit

“Since its inception in 1975, Standard 90.1 has been widely adopted as the benchmark for energy efficiency in buildings,” ASHRAE President Lynn G. Bellenger said. “It has set the foundation for energy efficiency in buildings in the United States and we expect that to continue internationally. No doubt, 90.1 has been a game changer in the building industry, and that influence is even greater today than it was 35 years ago.”

IES agreed, saying it is pleased and proud of its long-standing association with Standard 90.1, which began when IES provided technical support for lighting to ASHRAE Standard 90-1975. By the 1980 version of the standard the IES name was associated with the standard as a co-sponsor, a role that was formalized in a joint sponsorship agreement dated June 25, 1986. That agreement to jointly sponsor energy standards has continued to the present. It states that energy conservation standards must address all elements of the building that affect energy use and recognizes that ASHRAE has the primary expertise for HVAC&R and that IES has the primary expertise in illumination.

“Congratulations from the Illuminating Engineering Society of North America on this 35th anniversary of the standard,” Rita Harrold, IES director of technology, said. “It has been a wonderful personal experience for me to be involved with many of the 90.1 committees throughout this period of time in various roles – as an IES volunteer supporter in the early years and more recently as an IES staff liaison. Each committee has brought new information, new methodologies and new perspectives to revisions of the standard. Each committee has faced a series of different challenges in developing a consensus standard that achieves energy savings while remaining cognizant of the needs of users for a quality environment. Its success has been in allowing an open dialogue where technical opinions are heard and considered. The standard will continue to explore new strategies to save energy and IES will continue to fully support those endeavors.”

How has the standard contributed to reducing energy use? Figures show that, without consideration of plug and process loads, a building built according to Standard 90.1-2007 is 35 percent more energy efficient than one built in compliance with Standards 90-75 and 90A-1980. One built in accordance with Standard 90.1-2010, to be released later this year, is expected to use less than half the energy per floor area than one built to Standards 90-75 and 90A-1980.

“Between the launch of Standard 90 in 1975 and the 2004 version, we reduced building energy use by almost 33 percent,” Bellenger noted. “We are striving to reduce that by a further 30 percent in just six years from the 2004 standard to the 2010 version, and that is a huge challenge.”

Mick Schwedler, immediate past chair of the Standard 90.1 committee, stated, “Using analyses performed by a third party, the energy reduction from 90.1-2004 to 90.1-2010 is currently estimated to be between 21.7 and 30.9 percent, depending on modeling assumptions. While the range is large, assumptions such as ventilation rates and which loads to include in the final percentage calculation make a big difference. In addition, some of the energy-saving addenda approved by the ASHRAE Board of Directors at the 2010 Annual Conference have yet to be modeled, with final estimates expected in the fall. The volunteers on the committee have done an amazing job.”

Work on the standard – then known as the Design and Evaluation Criteria for Energy Conservation in Buildings – began in 1973. The U.S. government’s National Bureau of Standards had previously started on a standard at the request of National Conference of States on Building Codes and Standards (NCSBCS). In 1974, NCSBCS asked ASHRAE to assume responsibility.

The goal of ASHRAE was to provide a method of designing the energy consuming systems in a building and to evaluate these systems so that the overall energy consumption could be reduced to a minimum while still maintaining occupant comfort.

Since being published in 1975, the standard has been republished six times, evolving as input from the building community was given and as technology changed. Some 38 states currently have building codes that meet or exceed a version of 90.1.

In 2009, the 2004 version of the standard was established by the U.S. Department of Energy (DOE) as the commercial building reference standard for state building energy codes under the federal Energy Policy Act.