The Energy Rating Index: What does the future hold?

By Ryan Meres, IMT

A little over a year ago, I wrote a blog about the Energy Rating Index (ERI), the new compliance path included in the 2015 International Energy Conservation Code (IECC). With the 2018 version of the IECC being developed this year, it seems appropriate to look at the success of the ERI and what the future may hold.

A Quick Refresher
The voluntary ERI path for the 2015 IECC gives builders the option of complying with the code by meeting a target Energy Rating Index score. This is a numerical score where 100 equates to the efficiency levels prescribed in the 2006 IECC and 0 is equivalent to a net-zero-energy (NZE) home. One example of this score is RESNET’s Home Energy Rating System (HERS). In addition to meeting the ERI target for a home’s climate zone, a builder using the ERI to show compliance must also meet the envelope requirements of the 2009 IECC.

ERI Increases in Popularity
There have been about a dozen states that have either adopted the 2015 IECC (with the ERI path) or are in the process of reviewing the code for adoption. There are also more than 150 local jurisdictions that have adopted an ERI-based compliance path.

The increasing popularity of the ERI path is also apparent in the significant increase in homes being issued a HERS Index Score. According to RESNET, “over 190,000 homes in the U.S. were RESNET HERS Rated and issued a HERS Index Score in 2015”. That figure is a 30 percent increase over the number of homes rated in 2014 and represents over 38 percent of all new homes sold in the U.S last year. In 2015, 41 states and the District of Columbia all saw an increase in the number of HERS rated homes compared to 2014.

Many builders have decided to get an energy rating index for their homes because it provides a market advantage that is gaining recognition in many Multiple Listing Services (MLS). In fact, there are MLSs in more than 10 states that allow ERI scores to be included in the listing.

ERI in the 2018 IECC?
There are sure to be many proposals to revise the ERI path when the International Code Council (ICC) publishes the code change proposals for the 2015 IECC in March. One set of proposals certain to create a lot of debate will focus on how the ERI path treats renewable energy, especially solar PV. Although the commercial chapter of the IECC has recognized renewable energy as part of its additional efficiency options, the residential chapter has yet to follow suit. Programs like RESNET’s HERS Index allow for renewable energy to count toward the index score, which has spurred debates in many states adopting the 2015 IECC as to whether or not renewables should be included in the index score when it is being utilized as an energy code compliance path.

There are several questions central to this debate:

  1. Should renewable energy be allowed in a code whose purpose is the conservation (and not the production/generation) of energy?
  2. If renewable energy is allowed in the ERI path, should there be a minimum level of efficiency that is required prior to allowing credit for renewable energy, such as the 2009 IECC envelope backstop?
  3. What should this level of efficiency be?

These questions and others will be addressed by the 2018 IECC Residential Energy Committee between April 17 and 27 in Louisville, KY. The final answer to these questions will occur later this year after ICC’s Group B Public Comment Hearings in Kansas City, MO in October.

Recent history has shown the growing popularity of the ERI path among builders, but the future of the ERI in the 2018 IECC remains to be seen.