Why all HERS®/ERI Index Scores are Increasing Nationwide

It is important to understand the Home Energy Rating System (HERS®) and Energy Rating Index (ERI) are describing the same thing. HERS is a proprietary acronym created by the Residential Energy Services Network (RESNET), so the term ERI has been used for the code language. RESNET is the governing and standard setting body of the home energy rating world. RESNET recently created the ANSI/RESNET/ICC 301-2014 standard that describes how the Index score is developed. Within the 2015 IECC language that used to describe how to develop an ERI score has been replaced in the 2018 IECC with the ANSI 301 standard. In addition, the standard has now been incorporated into every software used to develop a HERS® or ERI Index score.

The ANSI standard change has, and will, cause all HERS/or ERI index scores to increase across the country. Due to this score increase and other fixed mandatory requirements in the ERI pathway, it is unlikely that jurisdictions will see builders using the ERI path for quite some time.

For more information on why this is happening, please refer to the following article: HERS® Energy Rating Index Scores are Going Up!

Software developers have incorporated the new ANSI/RESNET/ICC 301-2014 standard into their systems. As stated before, they are all consistently seeing the HERS/ERI index scores increase. Currently, there are three software systems available:




EnergyLogic is in the process of transitioning to the Ekotrope compliance software which will change the look of the reports but will not affect the content of the reports. Click here to see a sample Ekotrope report. All three software versions have incorporated reference homes to developed code compliance documents for the UA Tradeoff, Simulated Performance, and Energy Rating Index pathways through the energy codes.

What is a reference home?

Imagine your two hands are two homes that are geometric twins of each other. Your left hand, the reference home, is a house built with the energy and aesthetic features defined by the code which uses a quantifiable amount of energy that the code has deemed to be the minimum amount allowed by the jurisdiction.  Your right hand is the home you want to build, the proposed design, with the energy and aesthetic features you believe, are best to achieve whatever goal you have for the home: cost- effectiveness, safety, aesthetic beauty, comfort, durability, efficiency or livability. Your home, the proposed design, on the right, is compared to the code reference home on the left and if your home’s performance is equal to or better than the reference home it complies with the code and can be permitted to be built. The jurisdiction, an approved third-party, or both will inspect, verify, and report that the home was built as proposed in order for the certificate of occupancy to be released. 

For more detailed information, please refer to the following article: Simple Explanation of the IECC

In summary, changes and upgrades to software systems are inevitable. The creation of the ANSI/RESNET/ICC 301-2014 standard was the most impactful, but every version upgrade affects something. As a result, RESNET has developed a standard that governs when Energy Raters must transition to the most recent version of a software.

For more information on this subject, please refer to the following article: Important RESNET® Amendment on Rating Software Changes (Persistence)


Robby Schwarz (faked)

Who to Contact:

Robby Schwarz
Principal, Director of Builder Relations

Email Robby

Energy Rating Index Scores are Set to Go Up

new-resnet-logoIn July of 2015, EnergyLogic began informing you about the upcoming software changes that are set to go into effect in July of this year. As a reminder, the Residential Energy Services Network (RESNET®) began to align the energy rating reference home to the 2006 IECC almost two years ago. The reference home, which currently reflects the 2004 IECC supplemental code, is the home that your home is compared to in order to create the HERS® Index score. RESNET has gone through a process of taking the rule set for how to develop the HERS Index score through the ANSI process in order to create the ANSI/RESNET/ICC 301-2014 Standard for the Calculation and Labeling of the Energy Performance of Low-Rise Residential Buildings using an Energy Rating Index. The main impetus for this ANSI Standard arose from the desire to use the Index score for code compliance and the adoption of the Energy Rating Index (ERI), a HERS path, as a compliance matrix for the 2015 IECC.

The alignment with the 2006 IECC has three primary effects on the HERS reference home. First, the updated 2006 IECC reference home infiltration rate got tighter to better reflect the improved tightness levels of newly constructed homes. Second, the updated 2006 IECC reference home window solar heat gain coefficient (SHGC) went from 0.55 in climate zones 4 through 8 to a SHGC of 0.40 in those climate zones. This updated value reflects the market penetration of improvements in basic window technology and is in alignment with the 2006 IECC. Lastly, revised mechanical ventilation requirements are used in the HERS reference home which are now aligned with the ASHRAE 62.2-2013 ventilation standard.

Philip Fairey, Deputy Director of the Florida Solar Energy Center and a consultant for RESNET, performed research on the impact of these changes in the reference home on the HERS Index values of rated homes in all eight climate zones. His research has demonstrated that the HERS Index values will increase across all climate zones by a range of 2 to 6 points due to the reference home alignment with the 2006 IECC that occurred through the creation of the ANSI/RESNET 301-2014 Standard. EnergyLogic has been working with the newly released software, and as of now, we are seeing similar results when comparing homes that were rated with software developed prior to the ANSI standard adoption. RESNET is mandating that HERS providers begin using the new software on July 1, 2016. EnergyLogic is working with RESNET to find ways to reduce the impact of the implementation of the ANSI standard.

The development of the ANSI standard has also given RESNET the opportunity to include additional features related to water heating energy use. Specifically, this is an effort to include the energy use that is part of hot water distribution and is not about water conservation. RESNET is working on a Water Index score that will address water conservation. The ANSI standard addendum allows the HERS Index score to quantify the efficiency or loss of energy through pipe runs from the water heater to the farthest fixture, through hot water pipes that are insulated, on demand recirculation systems, high efficiency-low flow fixtures, and drain water heat recovery systems. If all of these systems are deployed in a home, the technologies can provide approximately a 3-point reduction in the HERS Index for builders.

These changes will affect every home that is rated, but should have minimal impact on the use of the Index score for demonstrating compliance with programs such as ENERGY STAR® as the program’s energy Index target will fluctuate in unison with the home that is being rated. In the same way, these changes should have minimal effect on code compliance when utilizing the Simulated Performance path, because the code reference home is separate from the HERS reference home. For those few builders utilizing the 2015 IECC Energy Rating index path, these changes will be significant. Lastly, all rated homes will be affected and therefore all builders utilizing the index score in their marketing efforts will need to update HERS related marketing collateral.



By Robby Schwarz

On December 18th, 2015, during the closing hours of the 2015 legislative session, President Obama signed into law the extension of several expired tax provisions, including the 45L $2000 federal tax credit for high-performing energy efficient new homes.  You may remember that the $2000 tax credit expired on December 31, 2014. This new legislation made the tax credit retroactively available for homes built in 2015 and extended it for homes built in 2016.

Unlike the last reauthorization of this legislation, no changes were made to the requirements for a home to qualify for the tax credit. The last reauthorization changed the basis of the tax credit from the 2003 to the 2006 International Energy Conservation Code.  We learn that this change has made it significantly more difficult to qualify.  That being said, we continue to believe that it does not make sense for builders to make a specification change in an effort to capture more tax credit dollars, unless we know that the credit will be extended beyond 2016.  If you would like us to run an analysis on your homes to identify what specification changes would lead to higher compliance, we will be happy to do that though our consulting services.

How the Tax Credit works:

 Many may not remember how the tax credit qualification is actually quantified. Your house is imputed into the modeling software tool. Within that software (REM/Rate) the house is duplicated, thus creating two houses that are geometric twins; House A and House B.  House A is assigned the energy specifications that are outlined in the 2006 IECC and House B is assigned the energy specifications you, the builder, actually used. The tax credit is issued for House B when it is 50% more efficient in heating and cooling energy use than House A, built to the 2006 IECC.  For the modeled “House,” the software determines what the 50% target is and if the as built house (House B) is performing equal to or better than the 50% targeted energy use.

The tax credit adds one further complication in that it has created a two-part test to demonstrate 50% compliance.  The home’s heating and cooling energy use must be 50% more efficient than the 2006 IECC, as measured by normalized end-use loads and the building envelope component loads. The building envelope component loads alone must account for at least 10% of those savings. If both of these tests pass, the house qualifies for the tax credit.  According to the software compliance reports, a majority of homes pass the envelope loads test but do not always pass the normalized end-use loads test. Normalized end-use loads account for the differences in equipment types that exist when using gas or electric utilities.  This is a bit of a ‘black box’ calculation; this portion of the compliance matrix has to be addressed by a specification change in order to capture more rebates.

Only homes that are tested and inspected can qualify for the tax credit.  While we can do some analysis to help increase the percentage of the homes that will qualify, it is unlikely that 100% of your homes will ever qualify.  This is because the analysis utilizes a whole-house evaluation and some of the parameters are not in the builder’s control, such as house orientation.

In order to claim the tax credit, you will need the tax credit certificate from us and IRS Form 8908.

Crawlspace Modeling isn’t all Runways and Catwalks

In or Out

Modeling crawlspaces in REMRate can be a challenge for new and experienced raters alike. Building codes and misconceptions among designers and builders have only served to further the problem over the years.  I hope to offer some clarity on the issue here.  Like an indecisive dog, the latest boy band, or the hottest runway model, crawlspace modeling comes down to one question: are you in or are you out?

First, let’s cover some important language.  In REMRate, we get to choose between three types of crawlspaces: open, enclosed, and conditioned.



 An “open” crawlspace is one without a true foundation wall enclosing it.  The outside “walls” may be closed in with a skirting or lattice, but that is mostly for aesthetics.  There isn’t truly a wall for “open” crawlspaces, so essentially we have outside conditions in that space.


A “conditioned” crawlspace is a crawlspace that is actively being conditioned to at or near the set point temperature of the home.  The important thing to determine is whether or not there is active space conditioning.  There are two additional key items to model for homes with conditioned crawlspace.  First, be sure to model the crawlspace floor in the slab screen in REM (whether it is made of dirt or concrete).  Second, a recent update in REM added “adiabatic” frame floors which must be modeled for homes with conditioned crawlspaces in order for REM to correctly configure the reference home.

REMRate Crawlspace Modeling


An “enclosed” crawlspace is a crawlspace that is enclosed at the perimeter with a foundation wall (block, brick, stone, concrete, etc), but not actively conditioned.  Once you’ve chosen this crawlspace type, you must define the venting conditions (unvented, vented, operable vents) and the thermal boundary location (floor or walls).

The Dreaded “Gray Area”

What about homes with partial basements that are wide open to a vented, dirt floor crawlspace?  Now what?  The basement air is being conditioned and that air is shared with a vented crawlspace.  Is the crawlspace then conditioned by association?  What if the crawl started out as “open” only for the walls to be poorly retrofitted in later with stone?  Is this still open, or is it an enclosed crawl with a leaky wall?  When all else fails, go back to the original question (the same one you want to ask your dog).  “You can be in or you can be out, but not both.  What’s it gonna be?”  In other words, will the crawlspace in question more closely track the set point temperature of the home (conditioned), the outside conditions (open), or will it be a true buffer zone staying somewhere in between (enclosed)?



Scott Doyle
Director of Energy Professional Services
EnergyLogic and EnergyLogic Academy