Get Ready for a Lower HERS Index in ENERGY STAR Version 3!

ENERGY STAR Homes, Version 3

Last week I got the new version of REM/Rate, the accredited home energy rating software that we use here at Energy Vanguard Energy Ratings, and it has the ENERGY STAR Version 2.5 and Version 3 requirements built in. I've checked a few files with it now, and it looks like the new requirements make a pretty big improvement in the HERS Index required for a home to qualify for the ENERGY STAR label.

In my first report on the ENERGY STAR Version 3 guidelines, I discussed the individualized HERS Index targets that a home would have to meet to qualify for the ENERGY STAR. Since 2006, most of the
country has had to come in at or lower than a HERS Index of 85, including IECC climate zones 2, 3, and 4, where most of our raters are. In the coldest parts of the US, the requirement is a HERS Index of 80 or lower.

With the Versions 2.5 and 3, each home has its own HERS Index target. As you can see in the table below, the average HERS Index for the 10 homes I sampled (all of which are in climate zones 2, 3, or 4) is 73.

energy star homes version 3 hers index table iecc

Notice that, based only on the HERS Index, all of these homes qualify in Version 2, but only 3 qualify in Version 3. The new HERS Index target goes into effect with Version 2.5, which applies to all homes permitted starting at the beginning of 2011. (See my article on the recent ENERGY STAR training I went to for the timeline showing when to use Version 2, 2.5, or 3.)

SAF in the table stands for Size Adjustment Factor, which is the penalty that houses have to pay when they go above the benchmark home size. Of the homes above, 5 were above the benchmark size, and thus had to meet a lower HERS Index to qualify, as indicated in the fourth column. The benchmark home size is the maximum size allowed without penalty for a house with a given number of bedrooms, shown in the table below.

As you can see, homes will definitely have to be more energy efficient to qualify for the ENERGY STAR homes label in Version 3 of the program. This requirement kicks in with Version 2.5, which applies to all homes permitted in 2011, as well as those permitted before 2011 but finished after 1 July 2011. Grade I insulation installation and reduced thermal bridging are two of the ways that homes will have to improve, both of which are required in Version 3.


This article has been cross-posted from the Energy Vanguard blog.

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Tags: 3, ENERGY, STAR, Version

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Comment by Allison A. Bailes III on December 2, 2010 at 4:36am
I just posted a 16 page white paper on ENERGY STAR Version 3 on our website, and you can download it for free by clicking the link below. In it, I cover what's new, what are most likely to be the difficult parts, advice for the various stakeholders (raters, builders, trades, & providers), and more.

http://bit.ly/hGyP1X.

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