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Building energy codes play a crucial role in promoting energy efficiency in residential buildings, and their adoption and enforcement are essential for reducing energy consumption and promoting sustainability. Energy codes are developed and published on a 3-year cycle, however, the efficacy of these codes in conserving energy relies heavily on their adoption and enforcement at the state and local levels. The International Energy Conservation Code (IECC), widely embraced for residential structures across 49 states (except California), serves as a benchmark for federal legislation.

While the IECC is not the ‘national energy code,’ it sets the Federal efficiency standard for residential buildings, encompassing single-family homes and small multi-story structures. Published as a national “model energy code”, the IECC is crafted with enforceable language applicable nationwide. Nevertheless, states and local jurisdictions retain the autonomy to modify these codes before adoption.

DOE Determinations

Upon publication of the IECC, the Department of Energy (DOE), mandated by the Energy Conservation and Production Act (EPCA), assesses the energy code’s efficiency for residential buildings, comparing it with the previous version. A positive determination by the DOE triggers specific obligations for states. Although states are not mandated to adopt residential building codes, those abstaining must confirm to the DOE that they have reviewed the newly published residential building code, accommodated public input, and opted not to revise their energy code. Failure to fulfill these obligations within 24 months of code publication could result in the loss of certain DOE funding.


Photo Credit: Pella

State Adoption Process

The adoption process for energy codes differs from state to state, but can generally be categorized into legislative adoption, regulatory adoption, or delegation to local jurisdictions (typically cities or counties) to adopt the appropriate energy code. However, all processes generally offer an avenue for stakeholders to provide input during the energy code review, even in states that ultimately adopt the energy code legislatively.

During most state adoption processes, amendments are considered to modify the published “model” code. Amendments may be intended to increase the efficiency of the code or may weaken the stringency of the code.

There are advantages and disadvantages to making changes to the published code. If the code as published is truly problematic for the state based on energy cost, climate, or other local situations, changes may make sense. However, when modifying the code, it can be problematic to disseminate the portions of the code that differ from the published version, training developed off the published version must be customized for the state, and compliance software must also be modified to accommodate amendments that deviate from the published code. It should be noted that changes that weaken the code may also eliminate the state from consideration for federal funding tied to the adoption of the latest published code.


Photo Credit: Andersen

Adoption Tracking

DOE closely monitors state code adoptions, considering not only the code publication year but also analyzing energy savings incorporating any amendments, thereby categorizing the efficiency relative to the as-published version of the applicable codes.

The figure to the left indicates that states are adopting energy codes at a slower pace than might be anticipated according to EPCA requirements. According to the Department of Energy, twenty-four states have a residential energy code equal to or below the 2009 IECC efficiency level, and 8 states lack a statewide energy code, although most jurisdictions within those states have adopted some version of the energy code.

DOE’s website provides an informative state portal resource to help understand the current energy code for the state, a link to the amendments (if any), the adoption process, and access contact information at the state level.  If you are interested in understanding the current state energy code or participating in the state-level adoption process, these resources offer ample information to become involved.


Photo Credit: Courtesy of the Department of Energy

Written by Craig Drumheller.

Craig Drumheller is the Vice President of Technical Activities with the Window & Door Manufacturers Association. He has been involved in energy efficiency research and energy code development for over 20 years. Craig has been a member of ASHRAE Standards 90.1, 90.2, and the IECC residential energy code development committee.

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