ATLANTA - Last year the Illuminating Engineering Society of North America (IES) and the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) joined forces to increase the efficiency of ANSI/ASHRAE/IES Standard 90.2, Energy Efficient Design of Low-Rise Residential Buildings, requirements. The standard provides minimum requirements for the energy-efficient design of residential buildings.

The two organizations are now seeking input into a draft of the standard, which is open for an advisory public review until June 12. The 90.2 committee is specifically seeking suggestions for input into Appendix B, which eventually will include checklists for practitioners on installation and proper application of requirements, as well as what type of application checklists should be included.

The goal of ASHRAE and IES is to publish a standard that is 30 percent more energy efficient than the 2004 version of 90.1 - including both a prescriptive and a performance path - and as the International Energy Conservation Code (IECC) 2006, as well as at least equivalent in energy efficiency to the 2009 IECC. As part of that effort, the two organizations are committed to developing a standard that is easy to use, has criteria that are economically justified, and requirements that are not too strenuous to meet.

The proposed standard contains four prescriptive paths (R-values) and performance paths (U-factors) for each of the eight climate zones. The multiple paths provide options to:

• Improve envelopes;

• Upgrade HVAC equipment efficiencies beyond National Appliance Energy Conservation Act minimums;

• Increase envelope air infiltration tightness and duct leakage tightness; and

• A combination of the above features.

Merle McBride, 90.2 committee chair, said, “This is the first time the standard has contained multiple prescriptive options, and the features in each path represent upgrades from previous versions. The combinations of the features in each path provide prescriptive options that users can select based on the type of construction and features that best meets their needs. One of the key attributes is the integration of multiple measures including envelope features, improved HVAC equipment efficiencies, lighting, and reduced air leakage in the envelope and air distribution systems.”

“In addition, the annual energy cost tradeoff option is retained, which allows users to conduct whole-house simulations that can be used to trade off energy-efficiency measures for any feature of the residence, including envelope, lighting, HVAC, and service water heating,” he said.

The title, purpose, and scope of the draft standard were expanded to include new features such as criteria for lighting, pools and spas. In addition, the format, structure and organization of the standard were changed to make it easier to understand and simpler to use.

For more information, visit www.ashrae.org/publicreviews.

Publication date: 05/30/2011