By Ryan Meres, RESNET Programs Director The process for developing the 2027 edition of the IECC has begun. With the goal of moving states toward market-driven efficiency improvements, RESNET has submitted two proposals to add new appendices to the residential section of the IECC. The proposals are to align the Energy Rating Index (ERI) target scores to state-adopted energy code efficiency levels and provide states with an optional path to improve long-term energy efficiency, starting with their current energy code efficiency level. The proposals are: Proposal 1: (Aligning ERI Target Scores with State Code Efficiency Levels (RE210-24) The premise of this proposal is that the ERI compliance option was not included in the IECC until the 2015 edition. Currently nearly half of all states are under the 2009 IECC efficiency levels. Although many states have adopted versions of the IECC that are more recent than 2009, the U.S. Department of Energy’s Building Energy Codes Program (BECP) lists 21 states with efficiency levels at the 2009 IECC or less (State Portal Building Energy Codes Program). The map below shows the version of the IECC in all states that BECP categorizes as under the 2009 IECC efficiency levels. (Note: this map excludes Arizona and Arkansas which BECP lists as less than 2009 efficiency levels). Since the Energy Rating Index (ERI) compliance option wasn’t instituted until the 2015 version of the IECC, states don’t have a reference for ERI target scores in these 21 states. Seven states have adopted a more recent version of the IECC (2015-2021) but have rolled back envelope levels closer to the 2009 IECC, while maintaining the ERI target scores from the model code. This makes the ERI path significantly more stringent than the state’s adopted code and therefore an unusable compliance option. The map below shows states that have adopted a more recent version of the IECC, rolled back envelope levels to near 2009 IECC efficiency, but made no change to the ERI target scores in the model code. Even for states that have energy codes with efficiency levels between the 2015 and 2018 IECC, the ERI target scores included in those model codes are much more stringent than the prescriptive compliance option. For this reason, the proposal includes ERI target scores that more accurately align with the prescriptive compliance options in those codes. The intent of this proposal is to give builders an ERI compliance option that aligns the prescriptive efficiency of older versions of the IECC with ERI target scores. RESNET Building Registry data of HERS® Rated homes shows that when builders work with third-party energy professionals to measure the energy performance of their homes, energy efficiency improves beyond the state code minimum. In fact, in states under 2009 efficiency levels, builders have improved HERS scores by 8 points on average since 2013, despite no change in their state’s energy code stringency. This proposal to give builders an appropriately aligned ERI target score is the best way for them to start measuring their efficiency and serves as the gateway to beyond code programs and energy efficiency incentives. Proposal 2: Pathway to Energy Efficiency As described above, 21 states have not advanced their energy code efficiency level in nearly 15 years. A pathway that provides flexibility for cost-effective energy code compliance is needed to advance residential energy efficiency. The purpose of this proposal is to provide such a pathway by meeting states where they are and setting ERI target scores that steadily decrease over time. The benefits of this proposal include: • States can choose a starting point, based on their current code efficiency level • States can choose the frequency by which the target scores decrease (get more efficient) (3 years is recommended) • States adopting this pathway give builders plenty of time to prepare to meet each stage of decreased target scores • Building thermal envelope backstops are determined by the state’s adopted code • For quality assurance, this compliance path requires compliance verification by a third party • Builders working with third party energy consultants have the benefit of expert advice on reducing energy consumption in a cost-effective manner, often exceeding code requirements • Using an ERI-based approach gives builders an entryway into incentive programs, like ENERGY STAR, Zero Energy Ready Home and the federal tax credits associated with those programs as well as local utility incentives. One example of the successful implementation of this concept is Texas House Bill 3215. This bill updated the state’s universal energy code compliance pathway to allow builders to use the HERS Index (with 2018 IECC envelope backstops) for homes permitted after September 1, 2021. The graphic below shows the HERS Index target scores for each climate zone, with successively lower requirements every three years. This energy code compliance option allows builders to plan and be prepared for lower target scores before they take effect. Contrast that with the typical energy code adoption cycle which implements a new code, then provides a three- to six-month grace period before builders must comply. This often leaves builders scrambling to update their plans, specs and contracts with suppliers and trades. This Texas example also shows the incredible potential of market-driven efficiency improvements this type of policy unleashes. When HB 3215 went into effect, the average HERS Index score in Texas was 59. In just three years the average score went down to 53. In addition to improvements in energy efficiency beyond those required in the House Bill, the number of HERS Ratings increased from one-third of all new single-family homes being rated in 2021 to two-thirds in 2024. The impact of these HERS rated homes, compared to the state’s 2015 IECC energy code, are estimated to annually save: • Over $58 million dollars in energy costs for Texas families who bought these homes • Over 325 million kWh of electricity • Over 4.4 million therms of natural gas • CO2 emissions savings equivalent to taking more than 29,000 vehicles off the road. These significant levels of energy and carbon savings were made possible by giving builders a flexible energy code compliance option that enables market-driven energy efficiency incentives like utility rebates, 45L energy efficient new home tax credits and green mortgage-backed securities offered by Fannie Mae and Freddie Mac. RESNET’s 2027 IECC proposals will be heard by ICC’s Residential Energy Code Committee in the coming months. The successful adoption of these proposals into the 2027 IECC will give states and jurisdictions two important options for an energy code compliance path that reflects the efficiency levels of their adopted code while spurring, market-driven advances in energy efficiency.
