The Breakdown on ERI
By: Lilly Liang
The Energy Rating Index (ERI) is one of the many important changes in the construction industry. If you’re panicking and asking yourself, “how does it work?!” Luckily, we are here to break down the facts for you.
What are the current compliance options?
- The Prescriptive Path: If you choose the prescriptive path in the code, you can look at the prescriptive tables in the energy conservation code and install the R-Values listed. For clear majority of new homes in NC, the 2018 NC Energy Conservation Code this will require R-15 walls and R-38 ceiling insulation.
- Total Building UA Trade-off: This is the methodology REScheck is built on. REScheck is a total UA trade-off software tool used to demonstrate compliance with energy code requirements As the name suggests this only allows tradeoffs to the building envelope R-Values and window U-Values.
- Energy Cost Compliance Option: This is full energy simulation (REM design, REM rate, Ekotrope, Energy Gauge, and so forth). This works by comparing the simulated energy cost of a code-built home to the simulated energy cost of the as-built home. If the simulation shows the as-built home will use the same or less energy as the code-built home, then it passes. This report must then be signed off by a Registered Design Professional.
- Energy Rating Index (ERI): In the most recent versions of the IECC, there’s another new path, the ERI. The ERI requires the same level of detail as the Energy Cost Compliance Option but can be performed by a HERS Rater instead of a Registered Design Professional. The ERI works by comparing an Energy Index calculated according to the 2018 NCECC. One down side of the ERI is that it has an R-Value “backstop” that does not allow you to go any lower than the prescriptive R-Values spelled out in the 2012 NCECC.
How does the ERI benefit me?
Generally speaking, the ERI is less expensive to implement than following the Prescriptive Path for Energy code compliance. This is true because an average house will cost $400-$600 to upgrade insulation, but the ERI will cost less to perform.
For builders, using spray foam the ERI will not allow you to go as low as R-19 on the roof deck so the Energy Cost Performance Option will be your best bet.
In addition to less cost, the ERI will allow your Energy Rater to generate a HERS index for the home which can be a helpful sales tool. If your Energy Rater participates with the Assure Performance program you can also get an Energy Cost Index and projected utility costs for the future homeowner.
How do you get an ERI?
Through modeling and inspections done by a third-party verifier (Ahem…Performance Point), you can get an ERI. The ERI option uses appliances, HVAC, and more, in additional to the envelope features.
“When we are all familiar with doing the performance path, and when we do the performance path, then we have our standard reference home and we have our model home. It’s the same thing. When we look at this, we have our ERI reference home. This is the one that if we built it exactly to what the code required, it would use this much energy,” said Shirley Ellis, a member of the ICC Board of Directors.
Energy Rating Index to show the minimum requirements for each climate zone.
Who are you going to call? Performance Point!
On January 2019, the 2018 NC Code will go into effect with the 2012 IECC Code standards. That’s only three months away now so lets be ahead of the curve! We can help you avoid cost of the new energy code by doing the ERI instead. ERI is a good option for those who find it difficult to meet the new standard.
Performance Point has been in the industry for over 10 years now and we always stay updated in recent changes. It can be difficult to completely understand the ERI performance path so please contact us if you have any questions – firstname.lastname@example.org
RESNET ERI F.A.Q. – http://www.resnet.us/uploads/documents/RESNET_Energy_Rating_Index_FAQ_Factsheet.pdf
ERI Webinar Transcript – https://www.energycodes.gov/sites/default/files/becu/ERI_Webinar_Video_Transcript.pdf
REScheck – https://www.energycodes.gov/sites/default/files/becu/REScheck%20Basics%20Webinar%20Video%20Transcript.pdf