ATLANTA - The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) has announced that energy-savings measures related to variable air volume and cooling towers are being proposed for Standard 90.1.

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 standard currently are open for public comment.

Under proposed addendum l, closed circuit cooling tower requirements to help reduce energy consumption would be added to the standard. The addendum would add minimum efficiency and certification requirements for both axial and centrifugal fan closed circuit cooling towers, also known as fluid coolers.

“These requirements will provide consulting engineers, system designers, and contractors with guidelines for the selection of independently certified, energy-efficient closed circuit cooling towers,” said Mick Schwedler, chair of the 90.1 committee. “This change also will complement existing minimum and certification requirements for open circuit cooling towers, helping prevent confusion between the requirements for open vs. closed.”

Also open for public comment is addendum n, which extends variable air volume (VAV) fan requirements for large single-zone units. VAV fan control currently is required in the standard for multiple-zone systems. Extending VAV control to single-zone units would save energy by reducing fan energy consumption when space cooling loads are reduced, he said.

The change would take effect in 2012, allowing air conditioning unit manufacturers time to redesign and test their units. Manufacturers are currently redesigning to meet the 2010 phaseout of certain refrigerants.

“Utility rebate programs and other incentives should encourage wider demand for these units and help this requirement to see real savings before 2012,” he said.

In addition, addendum r, which would change informative Appendix G’s performance rating method into a normative appendix, is open for comment. Making the performance rating method normative, or required, would allow its adoption into advanced energy standards, such as proposed Standard 189P, Standard for the Design of High-Performance Green Buildings Except Low-Rise Residential Buildings, being developed by ASHRAE in conjunction with the Illuminating Engineering Society of North America and the U.S. Green Building Council. Additionally, language has been changed to make Appendix G enforceable allowing adoption by model codes.

Proposed addenda open for review until Oct. 14, 2007, are:

• Addendum h addresses any potential conflict between Standards 55, 62.1, and 90.1 and takes advantage of the energy savings potential of direct digital controls.

• Addendum j updates mechanical test procedures and references.

• Addendum n extends VAV fan requirements for large single zone units.

• Addendum q modifies vestibule requirements for Climate Zone 4.

Proposed addenda open for public review until Oct. 29, 2007:

• Addendum d modifies the requirements in both the lighting and envelope sections to better allow daylighting.

• Addendum f expands the roof requirements to include cool roofs, which are shown by research to reduce the conduction loads through roofs into conditioned space.

• Addendum g updates the building envelope criteria for metal buildings.

• Addendum i applies a four-zone lighting power density approach to exterior lighting requirements.

• Addendum k revises Tables 6.8.1E and 7.8 to identify the specific sections of the referenced standards; updates to reflect federal efficiency levels for residential water heaters; and adds a requirement for electric table top water heaters.

• Addendum l adds minimum efficiency and certification requirements for both axial and centrifugal fan closed circuit cooling towers. In addition, a reference to the Cooling Technology Institute test standard for closed circuit cooling towers has been added.

• Addendum m establishes, effective Jan. 1, 2010, an additional path of compliance for water-cooled chillers.

• Addendum o adds requirements for low voltage dry-type transformers.

• Addendum p provides the necessary pressure credits for laboratory exhaust systems that allow prescriptive compliance of systems serving fume hoods.

• Addendum r changes informative Appendix G performance rating method into a normative appendix. Additionally, some language has been modified to make the appendix enforceable.

Proposed addenda to ASHRAE standards are available during public review periods. To read the addenda or to comment, visit

Publication date:10/08/2007