One of the ASHRAE’s most popular guides has more than a half-million copies in circulation.

The Advanced Energy Design Guide series from the American Society of Heating, Refrigeration and Air-Conditioning Engineers has been downloaded or purchased since it was first released in 2005. Since 2008, the guides have been available at as a free download.

Using the techniques available in the books, structures can realize between 30 percent and 50 percent energy savings compared with ASHRAE’s 90.1 standard, “Energy Standard for Buildings Except Low-Rise Residential Buildings.” The series was developed with input from the American Institute of Architects, the Illuminating Engineering Society, the U.S. Green Building Council and the U.S. Department of Energy.

Don Colliver, an ASHRAE fellow, spearheaded the project during his time as society president.

“This is truly a dream come true resulting from a challenge issued during my ASHRAE presidential theme address in June 2002,” Colliver said. “I knew I wasn’t smart enough to do it but I knew that the team of people with whom I was associated would be able to get it accomplished — and they did.”