Mandatory HERS Ratings Coming Soon?

RESNET’s move to make the HERS Index a third compliance path to the IECC takes them from the safe shallow waters of working with builders to the more treacherous depths of actually regulating them. Beware unintended consequences.

William Fay, Executive Director, Energy Efficient Codes Coalition presented the following to RESNET Board of Directors on February 28.  

In December 2012, after learning that there would be an effort to add a third Energy Rating Index compliance path to America’s Model Energy Code (the IECC), I told [RESNET Executive Director] Steve Baden that while your immensely successful and growing operation was now on the vast and relatively shallow Atlantic shelf, it was about to find itself stepping off into very deep water.

By joining ICC’s Implementation & Enforcement Infrastructure, RESNET now finds itself in a different world than raters are accustomed to, with very different roles and responsibilities governed by statutory law:

  • There will be greater scrutiny over HERS Scores – Are they being used as a “loophole?” Can they be “gamed?” “Do the goals of HERS run contrary to the code in any way?”
  • There will be greater scrutiny of your relationship with the builders from the vantage point of regulator and enforcer.
  • There will be significant shift in concerns, stemming from two key mandates that currently differentiate the ERI from HERS:
    • Mandatory requirements, ALL of which must be met.
    • The Thermal Envelope, which must currently meet or exceed the prescriptive requirements of an IECC that is nearly three code cycles – 9 years – old.
  • In addition, RESNET has historically taken an “all of the above” approach – including on-site power generation – in HERS methodology. While this may make sense for “above code” or green-oriented programs, we believe RESNET should not support the use of on-site power production in the ERI calculation or to segregate it with two scores – one with generation and the other solely with energy use and conservation.resnet-hers-index-logo

That’s because the IECC is and always has been focused on energy conservation. If RESNET is seen as attempting to broaden the scope of the IECC to conform with the scope of the RESNET standard, stakeholders and policymakers may resist the inclusion of an ERI path in local and state code adoption altogether.

  • There will be many more people watching you who care about the IECC and its stated goal to “regulate the design and construction of buildings for the effective use and conservation of energy over the useful life of each building.” Three essential phrases in the IECC’s statement of intent are:
    • Use and conservation of energy” – onsite power generation has never been part of the IECC’s residential energy code compliance or calculations.
    • Each building” – every single inspected building must comply with the provisions of the IECC, and
    • Useful life.” – the IECC stresses thermal envelope improvements because they are are most cost effective at construction, are unlikely retrofits, and last for the entire 80, 90-, even 100-year life of the building.

We have already seen some jurisdictions where the ERI path has become “the path of least efficiency” – an irresistible magnet for some builders. It goes without saying that RESNET, its supporters and/or representatives should not advocate or support state or local adoption of the IECC with weakening amendments, nor should they support weakening future versions of the code, particularly as they pertain to the ERI compliance path.

It isn’t going to be enough that RESNET has partnered with ICC. RESNET will also have to be viewed as being broadly supported by the code officials themselves and also by the energy efficiency community that makes up EECC’s support base.

Let Me Address Three of These Concerns that EECC Has Proposed to Address in this Year’s Code Development Process to Complete the 2018 IECCC.

First, as mentioned earlier, there are two IECC mandates that differentiate the code from a HERS rating:

  • All mandatory requirements must be met, and
  • Thermal envelope must meet or exceed the 2009 prescriptive path

These two key requirements reassure code officials that the ERI is a legitimate code compliance option.

EECC has submitted a proposal that would require the mandatory requirements be met before the ERI software calculates as score. Our proposal will save the code official from having to go back and ask about each of the mandatory requirements.

EECC has also submitted proposals that will update the thermal envelope backstop to the prescriptive requirements of the current code, not three codes back.

We firmly believe that minimum mandatory measures are key to ensuring a minimum level of long-term energy efficiency. Our proposals address our concern that useful life is not currently reflected in HERS or other performance calculations. In contrast, the IECC’s minimum mandatory measures:

  • Recognize that the thermal envelope outlasts nearly all other efficiency features,
  • Address the free ridership associated with lagging federal equipment standards,
  • Address issues of peak demand and sizing, and
  • Ensure reasonable homeowner comfort.

For these reasons, EECC believes that RESNET training, software and compliance report/certificate should highlight the need to comply with IECC mandatory items and the thermal envelope backstop.

Second, while on-site power production has been a part of HERS for a long time, power production has never been part of the IECC. Furthermore, the fact that HERS is an ERI does not mean that the ERI path in the 2015 expanded the scope of the IECC to include power generation. EECC has submitted a proposal to make this fact crystal clear.

Allowing unrestricted trade-offs for on-site power production could have a severe negative impact on the IECC by:

  1. Reducing home efficiency in favor of onsite power production. As an example of the potential impact, a recent report found that in most parts of the country, a 4 kW photovoltaic array could reduce a HERS Index Score by 20-40 points.[1] Other analyses have found even larger potential reductions in the HERS Index Score.
  2. Offering the potential of virtually eliminating the need to incorporate efficiency measures into the home to meet the code. This would not only wipe out many years of progress in improving home efficient, it is fundamentally inconsistent with the scope and intent of the IECC, and it should not be permitted.

While we were glad to see that one of RESNET’s proposals seems to agree that allowing builders to count all on-site power production toward compliance is not good public policy, we don’t think your proposal goes far enough. For example, at a 52 ERI target, a 30 point solar system would still count as 20 points off the ERI score.

Regardless of RESNET’s position on the production/conservation argument, we believe it is critical that building code officials know what the ERI score is with and without the addition of on-site power in the score. This is particularly important because at least some states have already moved to exclude or limit on-site power in the ERI.

We urge you to modify RESNET’s training, software and compliance report/certificate to produce two scores – one without on-site power production for ERI path compliance with the IECC, and the second including on-site power for a typical HERS rating. By doing so, RESNET will boost the usability of the ERI at the local level and allow states to affirmatively choose which rating to adopt.

Finally, we believe that in addition to continuing to provide data that supports ever-increasing efficiency in home construction, RESNET should also support putting the 2018 and future versions of the IECC on a modest, but steady glide path of efficiency improvements.

EECC’s Flex Point proposal for the 2018 IECC would offer builders 36 cost-saving options in eight savings categories from which they would be required to choose measures achieving a 5% improvement in efficiency over the 2015 IECC.

Nearly all of the options reflect practices and technologies that are widely used by green builders across the nation.

We have simplified and updated the “Flex Points” – which was introduced in the last code cycle – and accommodated the ERI path to require a 5% ERI target improvement if compliance is by ERI alone.

The energy savings of each Flex Point has been calculated by climate zone by independent analysis of the prestigious energy analytics first ICF International. The magic of Flex Points is that by adding compliance options, it becomes a template for putting future codes on a glide path of efficiency choices: i.e., requiring 9 points for the 2021 IECC. And it allows states that amend the IECC to raise or lower the requisite points to accommodate those amendments.

We “stole” this idea from Washington State, which has successfully employed these flexible options beyond a prescriptive backstop for years.

We would appreciate RESNET’s support in our efforts to put the IECC on a modest, but steady glide path of efficiency improvements.

Thank you.

[1] Residential Energy Services Network, Inc. The Impact of Photovoltaic Arrays on the HERS Index (2015),

Reprinted with permission

3 Comments on "Mandatory HERS Ratings Coming Soon?"

  1. I would like to comment on perhaps a minor part of this issue but one I feel is important: why is it that a 12% efficiency penalty is automatically assigned to ratings where a duct leakage to outside (LTO) test is not done? In almost all of the homes I work on there are NO ducts outside the conditioned space and the test consistently yields results that are almost unmeasurable (I agree an LTO test is appropriate when ducts are outside). Myself and other raters find ourselves “going through the motions” running this time-intensive test and charging the builders for it just to claim that extra 12%. This unnecessary testing does not inspire confidence in the rating system. This needs to change.
    I was told way back in my early training that this penalty was assessed in the software because “most homes built in the country have ducts outside”. Well, this should NOT be the norm any more, and, indeed up north in homes built with basements it IS. The software needs to be modified so that a check box can be clicked confirming that all ducts are “inside” otherwise the penalty will be assessed, and the LTO test will need to be performed and the rating will COST THE BUILDER MORE if they want to get the better result. This will encourage builders to get with designs that bring all ducts inside, which is demonstrably a good thing for building efficiency and durability.
    Thank you for creating this efficiency code forum.

    • Cati O'Keefe | May 2, 2016 at 8:50 pm |

      Hi Mark,
      Thanks for your comment. And I hope you will keep us posted on trends, new ideas for Code Watcher, and what’s going on in your neck of the woods. This may answer your concern: The home energy rating software that creates the ERI score, such as REM/Rate, includes a checkbox that notes “Exemption – No Test Required” that sets leakage equal to the Total Duct Leakage so that a leakage to outdoors (LTO) test does not need to be performed in homes that have all ductwork in conditioned space. Hope this helps.


      • Thanks for the reply.
        I probably should have mentioned that my comment was in regard to the Federal tax credit.
        As a testing “grunt” in the field I am just following the protocols I’ve been told are needed for various programs. I realize now you were talking about the ERI score which I’ve not used. As far as I’ve been told however, the LTO test needs to be done for the EPACT tax credit and we can’t just check the box for the exemption, although I wish we could. Do you interpret the rules differently on this?

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