The Three to Watch: 2018 IECC Public Comment Hearing 

While there will be well over 200 building code change proposals for the 2018 IECC, we’ve identified the three topics that will likely receive the most attention.


1. Solar Tradeoff

Tradeoffs will be discussed at length at these hearings, but the topic of solar tradeoffs is a new branch of an old debate. Some would like to see solar receive unlimited credit, and in exchange, the thermal envelope requirements can be lessened to a certain degree. They argue that when evaluating the net power usage (from the grid), these homes perform even better than homes built to code. Furthermore, creating quasi-incentives for solar usage in the code will decrease our overall emissions output and make for healthier air for all.

Opponents point out the limited service life of solar panels, as well as their proven decreases in productivity over time. If the panels
are not replaced at the end of their life, or if they are removed (by Mother Nature or by choice), that can occur without any disruption to the safety and/or comfort of the occupants (compared to an HVAC system or windows), yet the home is left with a weakened envelope.

Others claim it’s in the self interest of some vertically integrated production builders because solar installations have become a notable revenue generator. In these instances, the panels might not be owned by the homeowner, but the solar division
of the home builder. This presents a number of questions about the status of the panels if: rates unfavorably change, net metering rules change, or the homeowner wants to change energy providers.

Since the solar tradeoff is being discussed in the context of the ERI path, one has to wonder about solar panels whose sole purpose is to provide power to heat and operate pools. The energy use of a pool falls outside the scope of the ERI path, so a home could get credit for having solar, but then use it in a way that is not reflected in the home’s ERI.

One HERS provider we spoke with said, “The IECC is about conserving energy, not producing it differently. Solar has it uses, but leave the solar out. As soon as you put it in, loopholes will be created and exploited. Houses will have problems because they overlooked basic building science in favor of solar.”

One way to look at this is the treatment of solar as a fuel source. Since solar is a renewable energy, will the code allow unlimited usage, even if it means the building envelope is less efficient? Or, will solar be treated the same as traditional fuel sources, in which case its use should also be conserved, even though it is both clean and abundant?

While there will be well over 200 code change proposals for the 2018 IECC, we’ve identified the topics that will likely receive the most attention.

2. ERI Path

At the hearings for the 2015 IECC, the ERI path was introduced. It couldn’t reference any standard, since none existed at that time. Nonetheless, the alternative compliance path was admitted into the code.

Since the 2015 IECC was published, a number of states have adopted the code with the ERI path. Some of those jurisdictions have adjusted the ERI levels higher than the model code. Some have eschewed the ERI path, but substituted a HERS rating in its place.

While on the surface they might seem the same, there are subtle differences, and that’s where this topic gets really tricky. The summary goes like this: The baseline home for the original HERS rating was based on the 2004 IECC supplement. The RESNET/ANSI/ICC Standard 301 is based on the 2006 IECC. Subtle difference, but enough that in some climate zones, an identical house going through the old and new rating methodologies could see a difference of 1-7 points, according to one HERS provider.

Also, because of the base code change, all the software had to be updated. That update was supposed to be completed by July 1, 2016. That means that technically, prior to the software update, no home was able to comply with the ERI path.

There is a proposal to reference the formal RESNET 301 standard in the IECC-R, instead of the informal ERI path as constituted. Typically, the code will only reference standards, and those can come from a variety of standard development organizations.

On the surface, it makes sense to go in this direction. The number of detractors, and their reasons, are copious. A well-known building scientist pointed out that there is a “small house penalty” and that a 60 on a large house is not equal to a 60 on a small house. He went on to say that within the building science community, the lower ventilation rates in ASHRAE 62.2-2010 are not only favored over the higher rates in ASHRAE 62.2-2013, they are back in the 2018 IRC. This is in direct conflict to the 2013 rates used in RESNET 301.

Depending on the outcome of RE166, there could be a divergence between the IRC and whatever the 2018 ERI path looks like. Two people interviewed felt that moving to RESNET 301 would shift an entire path of the code outside the control of the ICC and its governmental voting member reps.

Also mentioned was the fact that RESNET 301 includes facets that aren’t currently in the code, such as on-site generation. Since HERS is currently the most widely used energy rating system, some are hesitant to give RESNET a monopoly in the energy code.

Finally, it’s no secret that RESNET has struggled with quality assurance and consistency of ratings. In fact, the 2014 PNNL/ DOE report “Identification of RESNET HERS Index Values Corresponding to Minimal Compliance with the IECC Performance Path” found that: “When no building characteristics are accounted for, the range of Corresponding HERS Indexes spans 19 to 26 points, depending on climate zone. This finding is significant, suggesting that two homes that minimally comply with the 2012 (or 2015) IECC Performance Path can have HERS Index ratings that differ by as much as 26 points, which ostensibly represents a 26% difference in energy performance. When the most significant building characteristics are accounted for, the range of Corresponding HERS Indexes spans 5 to 11 points, depending on climate zone.”

In addition to all that, there are proposals to increase and decrease the ERI levels in the model code. Those in favor of raising the ERI levels state that it just gets them in line with the change noted above, and that it may not represent a decrease in efficiency. Others feel the current levels are too low to begin with, and point to utility rebate programs where the target HERS rating is in the 70s.

Meanwhile, those who would like to see the ERI levels lowered cite the 2015 national average HERS rating of 62, the relatively small gap between that and the model code levels, and don’t see a problem increasing the efficiency of the code. (It should be pointed out that an ERI level is not equal to a HERS rating.) Once the impact of solar tradeoffs is piled on to this debate, you can see how it gets very complex… very quickly.


3. Mechanical Equipment Tradeoff

This debate has become a triennial tradition. This particular tradeoff was first removed from the 2009 IECC, but this argument has returned for every code cycle since. Each time, the governmental voting members have voted to keep it out of the model code.

At this year’s code development hearing, the committee approved this proposal. However, there was an assembly motion to disapprove, and after a round of online voting, 57% of voters agreed, so the proposal was disapproved.

In RE-134, NAHB is taking a slightly different approach than their past three attempts to reinstate this tradeoff. They have proposed a UA backstop. Using a 115% multiplier, this would not allow a thermal envelope less than (approximately) a home built to the 2009 IECC. (In some climate zones, it would be more stringent than the 2009 IECC, while in others it would be less stringent.)

There are also seven public comments attached to this proposal, though most are seeking disapproval. According to one executive we spoke with, the problem resides with the NAECA standard. Because 80 AFUE is the lowest allowable (new) furnace rating, and nearly all furnaces installed in cold climates are 90 AFUE (or higher), a lot of credit would be given for something that’s already viewed as either necessary or commonplace in the market. Therefore, if an inordinate amount of credit is given, insulation levels could be lessened. That would lead to less efficient thermal envelopes, which would in turn make the efficient equipment run more often than would otherwise be needed.

Other proponents of RE-134 point out that such a tradeoff is allowed in the commercial energy code, as well as the ERI path of the residential energy code. One executive we spoke with called it “disingenuous” for proponents of the ERI path to also oppose an equipment tradeoff. Another person noted that window tradeoffs are already allowed, some states have chosen to amend their energy codes to allow equipment tradeoffs, and many above-code programs also allow an equipment tradeoff.

Both sides of this debate would probably agree that changing the NAECA standard would go a long way towards ending this seemingly never-ending argument. To get the NAECA standard changed takes an act of Congress! (Seriously; it needs their approval.) The Department of Energy could have spearheaded the update long ago, but faced resistance from the gas industry. It appears as though something may finally change on this front but not for another four or five years at the soonest.

The topics above, plus many other proposals, will get sorted out in Kansas City in late October and then online throughout November. It is our hope that the governmental voting member reps take in as much information as possible before casting their votes.

Mike Collignon is the executive director and cofounder of the Green Builder Coalition.