ANSI/ASHRAE/IESNA Standard 90.1, Energy Standard for Buildings Except Low-Rise Residential Buildings, provides minimum requirements for the energy-efficient design of buildings except low-rise residential buildings. An estimated annual energy savings of 13 percent relative to ASHRAE/IESNA Standard 90.1-2004 should result from a proposed addendum regarding air- and water-cooled chillers.

Product development for water-cooled chillers in recent years has focused on improving off-design and part-load performance where most of the operating hours occur, according to Drake Erbe, chair of the standard’s mechanical subcommittee. According to ASHRAE’s (American Society of Heating, Refrigeration and Air-Conditioning Engineers), under the proposed addendum, an alternative set of efficiency levels, Path B, is established for water-cooled chillers intended for applications where significant time is expected at part load. The proposed addendum also combines water-cooled positive displacement chillers into one category and adds a new size category for centrifugal chillers at or above 600 tons. All air-cooled chillers without condensers must now be rated with matching condensers. The minimum efficiencies of air-cooled chillers have also been updated.

The proposed addendum was developed by a team of Standard 90.1 members, industry manufacturers and energy advocacy groups, including the American Council for an Energy Efficiency Economy and the Air-Conditioning and Refrigeration Institute (ARI) and was supported by ARI chiller manufacturers.