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Chiller Proposal Aims for Energy Savings

By CP Editorial Staff October 2007 - Energy Efficiency

A proposed addendum regarding air- and water-cooled chillers, relative to ASHRAE/IESNA Standard 90.1-2004, could produce an estimated annual energy savings of 13 percent.

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. Fourteen proposed addenda to the 2007 standard, due out for publication later this year, are open for public comment.

Among the addenda is proposed addendum m, which establishes effective Jan. 1, 2010, an additional path of compliance for water-cooled chillers, as well as consolidation and new requirements for some existing categories.

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, says Drake Erbe, chair of the standard’s mechanical subcommittee. Variable-speed drive (VSD) technology has advanced and is finding widespread application in water-cooled chillers. The use of VSDs has led to off-design and part-load improvement of the chiller’s performance with efficiencies of up to 30 percent in integrated part-load value (IPLV).

The proposed addendum would establish Path B, an alternative set of efficiency levels, for water-cooled chillers intended for applications where significant time is expected at part load. All Path B chillers must be equipped with demand-limiting controls. Under this proposal, equipment can achieve compliance with Standard 90.1 by meeting the requirements of Path B or Path A, which are intended for applications where significant operating time is expected at full-load conditions. But the equipment must meet both full-load and IPLV levels to fulfill the requirements of Paths A or B.

The proposed addendum also combines water-cooled positive-displacement chillers into one category and adds a new size category, centrifugal chillers at or above 600 tons. The category type for air-cooled chillers without condenser equipment has been eliminated. All air-cooled chillers without condensers now must be rated with matching condensers.

Minimum efficiencies of air-cooled chillers also have been updated. Efficiencies in the inch-pound version of Standard 90.1 now are expressed in energy efficiency ratio (EER) for air-cooled chillers, kW/ton for water-cooled chillers, and coefficient of performance (COP) for absorption chillers, to reflect industry practices.

Proposed addend m to ASHRAE/IESNA Standard 90.1 is available during its public review period, which ends Oct. 29.


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