Changes to Building Envelope Standard Raise Concerns
As the American Society of Heating, Refrigeration and Air Conditioning Engineers (ASHRAE) works to revise the so-called building envelope standard, NAHB is accelerating its efforts to make sure that any changes keep cost-effectiveness in mind when adding additional energy conservation measures.
ANSI/ASHRAE/IESNA Standard 90.1-2004, Energy Standard for Buildings Except Low-Rise Residential Buildings, provides minimum requirements for the energy-efficient design of buildings except low-rise residential buildings.
The revisions are intended to make the standard easier to read. But in the process, the standard is including information on air leakage reductions from caulking, plastic wrap and spray coatings used in the building envelope that may not be scientifically accurate, NAHB said.
Some people involved in the ASHRAE process are relying on a report from the National Institute of Standards and Technology, which provided a way to model the technologies referenced in the standard. Because the numbers in the report did not square with reality, NAHB filed a request for a correction with NIST under the Information Quality Act. NIST denied NAHB’s request for a correction. However, the letter of denial cleared up several issues that were vague in the report, and there may be no need for more debate. NAHB still has the opportunity to submit an appeal, but it may not be necessary.
As clarified, NIST only asserts that energy savings will result if the methods work. However, it does not judge whether the methods described in the standard actually do work, which may open the door for NAHB’s arguments at the ASHRAE 90.1.
The NIST decision “holds the promise of preventing substantial confusion in the consensus standards process of ASHRAE and other standards development organizations,” the NAHB letter said. However, “many people claim that the report establishes that the modeled technologies will accomplish the leakage, energy and cost savings results of the models, and NIST's denial letter seems to be saying that NIST intends no such meaning...The leakage reductions are not established or proven by the report; their values are assumed in order to show how much energy could be saved by reductions of that magnitude.
“Instead, the NIST report says that if a technology achieved the assumed reductions in leakage, and if it did so at the hypothesized cost, and if energy costs were the ones used in the models, then the savings and cost effectiveness would be as the report calculated. If any of those assumptions is not met, the report’s results would not be duplicated. In short, different assumptions would produce different results,” the letter said.
NAHB is concerned that the technology referenced in the report does not work the way it is used in the report.
“It is unfortunate that some of the language in the report is not as careful as it might be to maintain the distinction between the simulation results and predictions of actual cost or energy savings,” according to NAHB staff.
NAHB is asking NIST for a clarification of the denial letter. Depending on NIST’s response to NAHB’s request for clarification, NAHB has until June 8 to appeal.
For more information, e-mail Calli Schmidt at NAHB, or call her at 800-368-5242 x8132.