Energy Disclosure Laws at Home Sale

Last updated: April 2026

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Quick Answer

The 2024 International Energy Conservation Code (IECC) is the latest model energy code, setting minimum efficiency standards for new construction in the USA.
The U.S. Department of Energy determined that the 2024 IECC achieves 7.8% site energy savings and 6.6% energy cost savings compared to the 2021 IECC.
This new code offers builders more flexibility in how they meet energy performance targets for residential buildings.
A key update in the 2024 IECC includes a reduction of prescriptive attic insulation requirements by R-11 across all climate zones.

The 2024 International Energy Conservation Code (IECC) represents a significant stride in improving the energy efficiency of new homes across the United States. Developed by the International Code Council (ICC), this model building code establishes minimum efficiency standards for various components of new construction, including walls, floors, ceilings, lighting, windows, doors, duct leakage, and air leakage 2024 International Energy Conservation Code. The U.S. Department of Energy (DOE) has analyzed the impact of the 2024 IECC, finding that it achieves a 7.8% site energy savings and a 6.6% energy cost savings when compared to the previous 2021 edition. This means that homes built to the new code will use less energy and cost less to operate from day one, offering tangible benefits to homeowners. The new code also provides builders with more flexibility and options to reach these higher compliance targets, making it both effective and practical for implementation.

What is the 2024 International Energy Conservation Code (IECC)?

The 2024 International Energy Conservation Code (IECC) is the newest version of a crucial model building code for energy efficiency in the United States. It was created by the International Code Council (ICC) in 2000 and has been updated every three years since then. This code serves as the industry standard for energy efficiency in new construction across the country. It is widely adopted by states, counties, and municipalities, often forming the foundation for their local building codes. The IECC sets clear, minimum efficiency standards for how new buildings must perform. These standards cover many parts of a home, from its basic structure to its energy-using systems.

Defining Minimum Efficiency Standards

The IECC specifically targets the energy performance of a new structure's physical components and systems. This includes the insulation levels in walls, floors, and ceilings, as well as the efficiency of lighting fixtures, windows, and doors. Beyond these visible elements, the code also addresses less obvious but equally important areas like duct leakage and overall air leakage within the building envelope. By setting these standards, the IECC aims to ensure that newly constructed homes are designed and built to minimize energy waste. This focus on minimum standards helps guarantee a baseline of energy performance for all new buildings, leading to more comfortable and less expensive-to-operate homes for future owners. The 2024 IECC is recognized as the national model energy code for low-rise residential buildings, highlighting its widespread influence and importance in the construction industry [2.

A Regularly Updated Benchmark

The International Code Council updates the IECC every three years to incorporate new technologies, building practices, and research findings in energy efficiency. This regular update cycle ensures that the code stays current and continues to drive improvements in building performance. The 2024 edition builds on previous versions, pushing for even greater energy savings while trying to maintain practicality for builders. For professionals in the energy code field, such as HERS Raters, understanding these updates is critical. The Ekotrope Blog states that "Understanding the updates to IECC 2024 is very important to HERS Raters and energy code professionals as it will be the benchmark for many states, counties, and municipalities moving forward" Overview of the 2024 IECC for Residential Construction. This means that the 2024 IECC will be the standard against which many new residential projects are measured and approved.

The Role of Local Adoption

While the IECC is a model code, its actual implementation depends on state and local governments adopting it. Many jurisdictions adopt the IECC as their energy code, sometimes with their own specific amendments. This process allows local authorities to tailor the code to their specific climate conditions, local building practices, and policy goals. For example, jurisdictions like Phoenix, Colorado, Illinois, Nevada, Clark County, Las Vegas, New York State, New York City, North Dakota, Rhode Island, Nashville and Davidson County, Austin, and Utah have adopted the IECC 2024, or are in the process of doing so Energy Code, 2024 (IECC 2024) | UpCodes. The fact that so many diverse areas adopt this code underscores its role as a foundational document for energy efficiency regulations across the country. When a jurisdiction adopts the IECC, it becomes legally binding for all new construction projects within that area, directly impacting the energy performance of homes built there.

How Does the 2024 IECC Improve Energy Efficiency?

The 2024 International Energy Conservation Code (IECC) makes significant strides in improving energy efficiency for new homes. The U.S. Department of Energy (DOE) has officially determined that this latest version achieves notable energy and cost savings compared to the previous 2021 edition. This determination provides a clear, data-backed understanding of the code's impact. Beyond just savings, the 2024 IECC also brings increased flexibility for builders, allowing them more options to meet the updated energy performance targets. This combination of higher targets and greater flexibility aims to drive real-world improvements in how homes are built and how much energy they consume.

Quantifiable Energy and Cost Savings

The U.S. Department of Energy's analysis is clear: the 2024 IECC delivers measurable benefits. The DOE found that new homes built to the 2024 IECC standards achieve a 7.8% site energy savings compared to those built under the 2021 IECC. This "site energy savings" refers to the energy consumed directly at the building site, which translates into less electricity, natural gas, or other fuels being used by the home. This reduction in energy use directly leads to financial savings for homeowners. The DOE also determined that the 2024 IECC achieves 6.6% energy cost savings when compared to the 2021 IECC. These savings mean that homeowners can expect lower utility bills, making energy-efficient homes not just environmentally beneficial but also more affordable to live in over time. These percentages highlight the incremental but meaningful progress made with each new edition of the IECC, pushing the entire construction industry towards a more energy-conscious future.

Increased Flexibility for Builders

One of the most significant changes in the 2024 IECC is the added flexibility it offers to builders. While the energy performance targets have become more challenging, the code provides a wider range of options for builders to achieve compliance. This flexibility is crucial for practical implementation in the field. Builders can choose from different strategies and technologies to meet the required energy performance, rather than being confined to a rigid set of prescriptive measures. The NAHB (National Association of Home Builders) noted this change, stating, "Although the 2024 IECC will achieve incrementally higher energy savings than the 2021 edition, the residential provisions will offer substantially more flexibility and a wider range of options for builders to achieve compliance." This approach acknowledges the diverse needs of different construction projects and climate zones, allowing for innovative and cost-effective solutions. This means that while the goal is higher energy efficiency, the path to get there is more adaptable, which can help speed up adoption and make compliance easier for the building industry.

More Challenging Performance Targets

Despite the increased flexibility, the overall goal of the 2024 IECC is to achieve higher levels of energy efficiency. This means that the energy performance targets set in the code have become more challenging. Builders must now design and construct homes that are inherently more efficient than those built under previous codes. This push for higher performance encourages the use of better insulation, more efficient windows, tighter building envelopes, and advanced HVAC systems. The combination of ambitious targets and flexible compliance pathways helps to ensure that new homes are not just meeting a minimum standard but are genuinely moving towards greater energy performance. For homeowners, this translates into a higher quality, more sustainable home with lower operating costs from day one. The updates reflect a continuous effort to reduce the energy footprint of the residential sector, contributing to broader energy conservation goals.

What are the Key Residential Updates in the 2024 IECC?

The 2024 International Energy Conservation Code (IECC) introduces several important updates specifically for residential buildings. These changes aim to enhance energy efficiency while also providing new opportunities and challenges for builders and energy code professionals. Among the most direct impacts are the revisions to insulation requirements, particularly for ceilings and attics. These adjustments reflect ongoing research and a drive to optimize energy performance across different climate zones, ensuring that homes are insulated effectively for their specific environments.

Revised Ceiling Insulation Requirements

One of the most notable changes in the 2024 IECC for residential construction involves ceiling insulation. The code has updated its prescriptive attic insulation requirements. This means that the specific R-values—a measure of thermal resistance—required for attic insulation have been adjusted. These changes are designed to fine-tune the insulation levels to ensure optimal energy performance. For homeowners, this means that new homes built under the 2024 IECC will have attic insulation levels that are specifically calibrated to meet the latest efficiency standards, potentially leading to better temperature control and reduced heating and cooling costs. The adjustments are part of the broader effort to make the building envelope as energy-tight as possible, reducing heat loss in winter and heat gain in summer.

Reduction in Prescriptive Attic Insulation

A significant detail within the revised ceiling insulation requirements is the reduction of prescriptive attic insulation by R-11 across all climate zones. This change might seem counterintuitive at first glance, as higher R-values typically indicate better insulation. However, this adjustment is part of the code's broader strategy to offer more flexibility and optimize overall building performance. It allows builders to achieve the required energy performance targets through a more holistic approach, rather than relying solely on extremely high attic insulation values. For example, a builder might combine slightly less attic insulation with other energy-saving measures, such as a super-tight building envelope, high-performance windows, or more efficient HVAC systems, to still meet or exceed the overall energy performance target. This nuanced approach gives builders more options while still ensuring the home is highly energy efficient. This change is highlighted in the Ekotrope blog, which states, "The prescriptive attic insulation requirements have been reduced by R-11 across all climate zones" Overview of the 2024 IECC for Residential Construction.

New Opportunities and Challenges for Builders

The updates in the 2024 IECC present both new opportunities and new challenges for the residential construction industry. On the opportunity side, the increased flexibility in compliance pathways allows builders to innovate and choose the most cost-effective methods to achieve energy efficiency. This could lead to the adoption of new materials, advanced construction techniques, or integrated systems that were not as easily accommodated under previous, more prescriptive codes. Builders can now tailor their energy efficiency strategies to specific project needs and local market conditions.

However, these changes also bring challenges. Builders and energy code professionals, such as HERS Raters, must stay informed about the new requirements and understand how to implement them effectively. The shift towards more challenging performance targets, even with increased flexibility, means that the bar for energy efficiency has been raised. This requires a deeper understanding of building science and energy modeling. Training and education will be crucial for the industry to adapt smoothly to the 2024 IECC. The goal is to ensure that new homes are built not only to code but also to deliver the promised energy savings and comfort for homeowners.

Which Jurisdictions are Adopting the 2024 IECC?

The 2024 International Energy Conservation Code (IECC) provides a foundational framework for energy efficiency regulations across the United States. However, it is a model code, meaning states and local jurisdictions must formally adopt it to make it legally binding. This adoption process can vary, with some areas embracing the code directly and others incorporating it with specific local amendments that tailor it to their unique needs and priorities. The widespread adoption of the IECC underscores its importance as a national benchmark for energy-efficient construction.

The Foundation for State and City Codes

The IECC 2024 acts as the blueprint for many state and city energy codes. It provides a comprehensive set of standards that local governments can use as a starting point. When a state or city adopts the IECC, it becomes the minimum standard for energy efficiency in new construction within that jurisdiction. This means that builders and developers must ensure their projects meet or exceed these requirements to obtain permits and pass inspections. The model code's structure allows for consistency across different regions while still providing room for local customization. This balance helps to ensure that new buildings are energy efficient, regardless of where they are built, while also addressing specific regional considerations.

Adopting Jurisdictions Across the Nation

Several states and cities across the U.S. have already adopted the 2024 IECC or are in the process of doing so. This demonstrates a growing commitment to higher energy efficiency standards in new construction nationwide. The list of adopting jurisdictions is diverse, spanning various climate zones and population densities. According to UpCodes, jurisdictions that have adopted the IECC 2024 include Phoenix, Colorado, Illinois, Nevada, Clark County, Las Vegas, New York State, New York City, North Dakota, Rhode Island, Nashville and Davidson County, Austin, and Utah Energy Code, 2024 (IECC 2024) | UpCodes. This broad geographical reach means that a significant portion of new homes built in the coming years will be constructed under the guidelines of the 2024 IECC, leading to cumulative energy savings across the country.

Adoption With or Without Amendments

The process of adopting the IECC can take two main forms: adoption "with amendments" or "without amendments." When a jurisdiction adopts the IECC without amendments, it means they are implementing the code exactly as written by the International Code Council. This provides maximum consistency with the national model. However, many jurisdictions choose to adopt the IECC with amendments. These amendments are local modifications that can either strengthen certain provisions, relax others, or add specific requirements unique to the area. For instance, Colorado and Utah have adopted the 2024 IECC with amendments Energy Code, 2024 (IECC 2024) | UpCodes. These amendments might address local climate challenges, specific building material availability, or local policy goals, such as promoting renewable energy or specific types of insulation. Understanding whether a jurisdiction has adopted the code with or without amendments is important for builders, energy professionals, and prospective homeowners, as it dictates the precise energy efficiency requirements for new construction in that area. This flexibility ensures the code remains relevant and effective across the diverse regulatory landscapes of the United States.

How Does the IECC Relate to Programs like ENERGY STAR?

The International Energy Conservation Code (IECC) plays a foundational role in the broader landscape of energy efficiency initiatives, extending its influence beyond mere compliance. While the IECC sets the minimum legal standards for new construction, it also serves as a critical benchmark for voluntary programs like ENERGY STAR and even affects qualifications for financial instruments such as HUD loans. These connections highlight how energy codes integrate with market-driven programs to promote higher levels of energy performance in residential buildings. The goal is to encourage builders to exceed minimum requirements and to provide consumers with clear indicators of superior energy efficiency.

IECC as a Benchmark for Initiatives

The 2024 IECC, with its updated and more challenging energy performance targets, naturally becomes a benchmark for various energy efficiency initiatives. It establishes a baseline that programs and certifications can build upon. For example, voluntary programs often require homes to meet standards that are significantly more stringent than the minimum IECC requirements. By continuously raising the bar for minimum efficiency, the IECC helps to push the entire industry forward, making it easier for advanced programs to achieve even greater savings. This symbiotic relationship means that as the IECC evolves, so too do the expectations and standards for what constitutes a truly energy-efficient home. The Ekotrope blog highlights this, noting an "update on the intersection of IECC 2024 and key Energy Efficiency initiatives like ENERGY STAR and HUD loan qualifications" Overview of the 2024 IECC for Residential Construction. This indicates that the code's updates are directly relevant to these programs.

Connection to ENERGY STAR Certification

ENERGY STAR is a well-known symbol for energy efficiency, backed by the U.S. government. The ENERGY STAR Residential New Construction Program specifically certifies new homes and apartments that meet strict guidelines for energy efficiency ENERGY STAR Residential New Construction Program. To earn the ENERGY STAR label, a home must be designed and built to be significantly more efficient than homes built to minimum code standards. While the IECC sets the floor, ENERGY STAR aims for a higher level, often requiring homes to be 10-20% more efficient than conventional homes built to code.

This program provides a clear pathway for builders to differentiate their homes as superior in energy performance. For homeowners, an ENERGY STAR certified home promises lower utility bills, enhanced comfort, and better indoor air quality Energy Efficient New Homes and Apartments. The certification process involves third-party verification, ensuring that the home truly meets the rigorous standards. This includes detailed inspections and testing by qualified professionals to confirm that the home's energy-efficient features are properly installed and performing as intended. The ENERGY STAR label helps consumers easily identify homes that offer verified energy savings and environmental benefits ENERGY STAR Certification.

Impact on HUD Loan Qualifications

Beyond voluntary certification, the IECC's influence can also extend to financial incentives, such as qualifications for HUD loans. The U.S. Department of Housing and Urban Development (HUD) offers various loan programs, and some may have provisions or advantages for homes that meet certain energy efficiency standards. While specific details can vary, a home built to the latest IECC standards, or even exceeding them with certifications like ENERGY STAR, might qualify for more favorable loan terms, energy-efficient mortgages, or other benefits. This connection provides a financial incentive for builders to construct more efficient homes and for buyers to choose them, as lower energy costs can directly impact a homeowner's ability to afford their mortgage payments. The integration of energy efficiency into lending criteria helps to reinforce the market for high-performance homes, making them more accessible and attractive to a wider range of buyers. By linking energy performance to financial benefits, these programs work in tandem with the IECC to accelerate the adoption of sustainable building practices.

Why is Understanding the 2024 IECC Important for Homeowners?

Understanding the 2024 International Energy Conservation Code (IECC) is crucial for homeowners, whether they are considering buying a new home or planning major renovations. This code directly impacts the energy performance of new construction, which in turn affects utility bills, comfort levels, and even the long-term value of a property. By being aware of the standards set by the 2024 IECC, homeowners can make more informed decisions, advocate for better building practices, and ultimately enjoy the benefits of a more energy-efficient living space. It's not just about compliance; it's about investing in a home that performs better and costs less to operate.

More Energy-Efficient New Homes

The most direct benefit for homeowners is that new homes built under the 2024 IECC will be inherently more energy efficient than those constructed under previous codes. The U.S. Department of Energy determined that the 2024 IECC achieves a 7.8% site energy savings and 6.6% energy cost savings compared to the 2021 IECC. These savings translate into tangible advantages for the homeowner from the moment they move in. A home built to these updated standards will feature enhanced insulation, tighter air sealing, more efficient windows, and potentially more advanced heating, ventilation, and air conditioning (HVAC) systems. This means the home will require less energy to maintain comfortable indoor temperatures, regardless of the season. For anyone buying a new home, knowing that it meets or exceeds these stringent standards provides assurance of its energy performance and long-term cost savings.

Lower Energy Bills and Reduced Environmental Impact

The improved energy efficiency mandated by the 2024 IECC directly leads to lower monthly energy bills for homeowners. When a home uses less electricity, natural gas, or other fuels for heating, cooling, and lighting, the costs associated with those utilities decrease. Over the lifespan of a home, these savings can add up significantly, freeing up household income for other priorities. Beyond the financial benefits, lower energy consumption also means a reduced environmental impact. Homes that are more energy efficient contribute less to greenhouse gas emissions, helping to combat climate change and reduce demand on power grids. For environmentally conscious homeowners, living in a home built to 2024 IECC standards aligns with their values and contributes to a more sustainable future. This dual benefit of financial savings and environmental stewardship makes understanding the IECC particularly relevant.

Making Informed Decisions

For homeowners, understanding the 2024 IECC empowers them to make more informed decisions throughout the homeownership journey. If you are purchasing a newly constructed home, you can ask your builder about the specific energy code it adheres to and what features are included to meet those standards. Knowing that a home is built to the 2024 IECC provides a benchmark for its quality and expected performance. If you are planning a major renovation or addition, being aware of the latest code requirements can guide your choices for insulation, windows, and other energy-related upgrades, ensuring that your improvements meet modern efficiency standards and maximize your investment.

Moreover, for those considering an older home, understanding the 2024 IECC can help you evaluate potential energy efficiency upgrades. You can compare the performance of an existing home to the latest standards and identify areas where improvements could lead to significant savings. This knowledge allows you to assess the long-term operating costs of any property and make a more financially sound decision. The NAHB staff, including the Senior Program Manager, Energy, Codes & Standards, noted that the 2024 IECC offers "substantially more flexibility and a wider range of options for builders to achieve compliance" 2024 International Energy Conservation Code. This flexibility, while aimed at builders, ultimately benefits homeowners by fostering innovation in energy-efficient design and construction.

Frequently Asked Questions

What is the primary goal of the 2024 IECC?

The primary goal of the 2024 International Energy Conservation Code (IECC) is to set minimum efficiency standards for new construction. This ensures that new homes and commercial buildings are designed and built to use less energy. The U.S. Department of Energy determined that the 2024 IECC achieves a 7.8% site energy savings and 6.6% energy cost savings compared to the 2021 IECC, showcasing its aim to continuously improve energy performance and reduce energy consumption.

How much energy can I save with a home built to 2024 IECC standards?

A home built to 2024 IECC standards is designed to be significantly more energy efficient than homes built under previous codes. The U.S. Department of Energy (DOE) found that the 2024 IECC achieves 7.8% site energy savings and 6.6% energy cost savings compared to the 2021 IECC. This means you can expect lower utility bills and reduced energy consumption for heating, cooling, and other uses over the lifespan of your home.

Does the 2024 IECC apply to existing homes?

The 2024 IECC primarily applies to new construction and major renovations or additions to existing buildings. It sets minimum efficiency standards for walls, floors, ceilings, lighting, windows, and air leakage in newly built structures. While the full code generally doesn't apply to existing homes unless undergoing significant changes, understanding its standards can help homeowners plan energy efficiency upgrades for their current properties.

Where can I find if my state or city has adopted the 2024 IECC?

You can check with your local building department or state housing authority to determine if your specific state or city has adopted the 2024 IECC. Many jurisdictions, including Phoenix, Colorado, Illinois, Nevada, Clark County, Las Vegas, New York State, New York City, North Dakota, Rhode Island, Nashville and Davidson County, Austin, and Utah, have adopted the IECC 2024, sometimes with local amendments. Websites like UpCodes can also provide information on jurisdiction adoption.

What are 'prescriptive attic insulation requirements' in the IECC?

Prescriptive attic insulation requirements in the IECC refer to the specific R-value (a measure of thermal resistance) that insulation in the attic must meet in different climate zones. The 2024 IECC includes updates to these requirements, notably reducing prescriptive attic insulation by R-11 across all climate zones. This change allows builders more flexibility in achieving overall energy efficiency targets through other measures while still ensuring a well-insulated home.