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CODE ARENA Green results vary. HERS raters
have proven to be inconsistent in
The Latest Rules, Regulations and Codes Impacting Sustainable Construction how they evaluate homes for their
energy efficiency.
CREDIT: SEWARD CONSTRUCTION CO.¢FLICKR
raters conducted a total duct leakage test, and only two of the ve
raters tested for duct leakage to the outside. Astonishingly, the total MANY QUESTIONS, FEW ANSWERS
area of wall square footage reported by the raters ranged from 2,187 The study states that “it is based on a relatively small sample of
s.f. to 4,250 s.f. Window area ranged from 242 s.f. to 451 s.f. The homes, and should not be considered statistically representative.”
number of returns ranged from ve to nine. When it came to ceiling Yet the very next sentence notes that “it…raises many important
fan energy usage, three of the ve raters didn’t mark anything down, questions for further inquiry.” The authors call out ve questions
and one rater entered zero for the refrigerator’s energy usage. for further investigation, but the most signi cant questions can
The study noted that a wide range of software was used, with only be answered in retrospect. The rst is: What reaction did this
the average home rated using three dierent versions of software study elicit?
and, in one instance, a particular home was rated with ve dierent To its credit, RESNET reacted fairly quickly. On April 19, 2018
versions of REM/Rate software among six raters. While it’s uncertain (approximately two months after the study’s results were conveyed),
if software had a signi cant contribution to the range of variability, RESNET adopted the HERS Software Consistency Collaborative
the inconsistencies noted above are independent of software. The Modeling Process [https://bit.ly/2VPrJEW]. One facet of this new
discrepancies can be attributed to either poor training or a failure eort was to recruit a “technical consultant with extensive knowledge
to execute the requisite training. of building energy software modeling” to serve as the RESNET
This study was incredibly important, because multiple jurisdictions Energy Modeling Director.
(states and cities) have incorporated alternative code compliance Unfortunately, that recruitment process took almost six months
paths built around energy ratings. As the study stated, “consistency to produce a new sta member [https://bit.ly/2NVAFWB]. Over the
and replicability of the rating process is crucial to the ERI path.” It course of 2018, RESNET made the following revisions to the quality
went on to say “while the HERS Index was not originally speci ed assurance aspects of the National Home Energy Rating Standards
within the ERI path of the 2015 IECC, the connection was made more after the variability study was released:
explicit when ANSI/RESNET/ICC Standard 301 was incorporated by ■ Added a compliance path to achieve Quality Assurance Designee
reference in the 2018 IECC.” (QAD) status, whereby the minimum number of reviews increased
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