by Brianna Crandall — April 11, 2012—A proposed change to the ASHRAE/IES energy standard regarding data centers recognizes the role that system efficiencies—vs. only equipment—can play in reducing energy consumption. The standard was created by international technical society ASHRAE (the American Society of Heating, Refrigerating and Air-Conditioning) and IES, the Illuminating Engineering Society of North America.
“This change regarding data centers represents a building block as we work to build on the foundation of energy conservation in the standard,” Drake Erbe, 90.1 vice chair, said. “We recognize that equipment used in buildings is reaching maximum capabilities in energy efficiency. We now must examine the role that system efficiencies play in saving energy. Inclusion of data centers in the standard was a step in that direction.”
With publication of the 2010 standard, ANSI/ASHRAE/IESNA Standard 90.1-2010, Energy Standard for Buildings Except Low-Rise Residential Buildings, data centers were included within its scope for the first time. Most data centers were required to have economizers, but some in the data center industry disagreed with the requirement, maintaining that economizers are subject to static discharge due to low humidity, gaseous contaminants and reliability.
Erbe said the 90.1 committee worked with the data center industry and ASHRAE’s technical committee on mission control facilities, technology spaces and electronic equipment to develop an alternative path known as power usage effectiveness (PUE) to allow use of developing technologies for which there are no energy modeling tools available. The path is addressed in proposed addendum “ap,” which is currently open for public comment.
“This is a significant issue to design professionals in that without a simulation program available to model these systems they have to receive approval from the authority having jurisdiction for an exceptional calculation method, which, in most cases, is beyond the jurisdiction’s knowledge level,” Erbe said. “The PUE values were developed using water cooled chillers with water side economizers and air cooled chillers with air side economizers, using prescriptive requirements currently in the standard. The PUE values for all climate zones are able to be achieved by both of these conventional system types.”
Also open for public comment is addendum “ao,” which offers an alternative compliance path for lighting requirements aimed at the large number of smaller, simpler buildings that make up a majority of new construction and retrofit activity, according to Eric Richman, chair of the standard’s lighting subcommittee. It provides a less complicated set of requirements that should be easier to apply to these types of facilities, and also includes more stringent Lighting Power Density (LPD) limits that may restrict the application of more lavish space lighting designs not commonly found in these facilities.
This compliance path will replace the current whole building LPD table and only applies to a subset of building types that encompass many of the smaller, simpler buildings. The use of this method is optional, and the full space-by-space method used by most designers for larger more complex facilities still remains for application to any building type, Richman said.
In addition, addendum “al” is open for public review. Users of Appendix G of the standard have noted that the baseline energy budget is different depending on whether electricity or natural gas is chosen for either space heating and water heating, according to Don Brundage, a member of the Energy Cost Budget subcommittee. In some cases, this can provide greater energy savings estimates from Appendix G when using one fuel versus another, and provides a strong incentive to specify the fuel that will provide the greatest energy savings using Appendix G.
“Proposed addendum ‘al’ would make the baseline building energy budget (the minimum code baseline for determining energy savings) the same regardless of the choice of fuel in the proposed building, eliminating this bias,” Brundage said. “This is done by setting rules to determine the fuel to be used in the baseline building for space and water heating. These rules are based on climate zones for space heating and type of building usage for water heating. This would make energy savings estimates using Appendix G more consistent and fair than under the current version of the standard.”
In total, 15 proposed addenda to Standard 90.1 are open for public review, some from March 23 until May 7 and others from March 23 until April 22.
