ASHRAE 62.2 Ventilation Standards

Last updated: April 2026

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Quick Answer

The 2024 International Energy Conservation Code (IECC) is the latest model building code for energy efficiency in new construction, updated every three years by the International Code Council (ICC).
The U.S. Department of Energy (DOE) determined the 2024 IECC achieves 7.8% site energy savings and 6.6% energy cost savings compared to the 2021 edition.
The 2024 IECC offers more flexibility for builders to achieve compliance, even though its energy performance targets are more challenging.
Key changes include a reduction of R-11 in prescriptive attic insulation requirements across all climate zones.

The 2024 International Energy Conservation Code (IECC) marks a significant update in energy efficiency standards for new construction across the United States. Developed by the International Code Council (ICC) and updated every three years, this code acts as the industry standard for energy efficiency. It sets minimum requirements for various building components, including walls, floors, ceilings, lighting, windows, doors, duct leakage, and air leakage 2024 International Energy Conservation Code (IECC). The U.S. Department of Energy (DOE) has determined that the 2024 IECC achieves 7.8% site energy savings and 6.6% energy cost savings when compared to the previous 2021 edition. This new code provides builders with more flexibility and options to meet compliance targets, even as overall energy performance expectations become more rigorous. For HERS Raters and energy code professionals, understanding these updates is crucial as the 2024 IECC will serve as the benchmark for many states, counties, and municipalities moving forward Overview of 2024 IECC for Residential Construction.

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

The 2024 International Energy Conservation Code (IECC) is the newest model building code designed to improve energy efficiency in new construction. The International Code Council (ICC) develops this code, updating it every three years to reflect the latest advancements and best practices in energy conservation. It serves as a foundational document for many state and city building codes across the United States.

Setting Minimum Efficiency Standards

The IECC sets clear, minimum efficiency standards for a range of building elements in new construction. These standards cover a structure's walls, floors, ceilings, lighting systems, windows, and doors. The code also addresses crucial areas like duct leakage and air leakage, which are vital for maintaining a building's thermal performance and preventing energy waste. By setting these standards, the IECC aims to ensure that new buildings are constructed to be more energy-efficient from the start, leading to reduced energy consumption and lower utility bills for occupants.

Widely Adopted and Recognized

The IECC is the most adopted energy code in the country. It is widely recognized as the national model energy code for low-rise residential buildings, making its updates particularly important for homebuilders and associated professionals. The 2024 edition continues this tradition, serving as the industry standard for energy codes in the USA. Its provisions will be the benchmark for many states, counties, and municipalities as they update their local building regulations. This broad adoption means that professionals working in energy efficiency, such as HERS Raters and energy code professionals, must stay informed about the code's requirements. Their work often involves verifying compliance with these standards, ensuring that new homes meet the necessary energy performance targets.

The Evolution of the IECC

The International Energy Conservation Code was first created in 2000. Since then, it has been regularly updated every three years, with the 2024 edition being the latest iteration. Each update introduces new provisions and refines existing ones, pushing the envelope for energy efficiency in construction. These updates are developed through a rigorous process that involves various stakeholders, including builders, energy experts, and code officials. The goal is to create a code that is both effective in achieving energy savings and practical for builders to implement in the field. The continuous evolution of the IECC reflects an ongoing commitment to making buildings more sustainable and reducing their environmental impact.

How Does the 2024 IECC Compare to Previous Editions?

The 2024 IECC represents a step forward in energy conservation compared to its predecessors, particularly the 2021 edition. While the new code introduces more challenging energy performance targets, it also provides builders with increased flexibility in how they can meet these standards. This balance aims to drive greater energy savings while ensuring practical implementation in the construction industry.

Significant Energy Savings Determined by DOE

The U.S. Department of Energy (DOE) has conducted an analysis comparing the 2024 IECC to the 2021 edition. Their determination shows that the 2024 IECC achieves substantial energy savings. Specifically, the new code results in a 7.8% site energy savings. This means that buildings constructed under the 2024 IECC will consume 7.8% less energy directly at the building site compared to those built under the 2021 code. Beyond just energy consumption, the DOE also found that the 2024 IECC achieves 6.6% energy cost savings. This translates to lower utility bills for homeowners, making new construction more affordable to operate over its lifetime. These figures highlight the tangible benefits of adopting the updated code. According to NAHB, "The U.S. Department of Energy (DOE) issued a determination on the 2024 IECC showing that it achieves a 7.8% site energy savings and 6.6% energy cost savings compared to the previous edition, the 2021 IECC" U.S. Department of Energy determination on 2024 IECC savings.

More Challenging Targets, Greater Flexibility

One of the defining characteristics of the 2024 IECC is its approach to energy performance targets. Overall, these targets have become more challenging. This means that new buildings must achieve a higher level of energy efficiency to comply with the code. However, the ICC and the committees involved in developing the code recognized the need for practical implementation. As a result, the residential provisions within the 2024 IECC offer substantially more flexibility. Builders now have a wider range of options to achieve compliance, allowing them to choose strategies that best suit their specific projects, local conditions, and construction practices. This flexibility is a key aspect that differentiates the 2024 edition, aiming to make the higher performance targets achievable without undue burden. NAHB states, "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 prioritizes cost-effectiveness and consumer benefits, while also maximizing design choices for builders. It also ensures that the code can be practically implemented in the field, which is a critical consideration for widespread adoption and success.

Continuous Improvement in Energy Efficiency

The incremental but significant improvements in energy savings demonstrate the continuous effort to advance building energy efficiency. Each new edition of the IECC builds upon the last, incorporating new technologies, materials, and construction techniques that contribute to better energy performance. The 2024 IECC's focus on both higher targets and increased flexibility reflects a maturing understanding of how to effectively drive energy conservation in the residential sector. This balance helps ensure that the code remains relevant, effective, and adoptable by jurisdictions across the country, leading to a steady increase in the energy efficiency of new homes.

What are the Key Residential Updates in the 2024 IECC?

The 2024 IECC introduces several important updates specifically for residential buildings, impacting how homes are designed and constructed to meet new energy efficiency benchmarks. These changes aim to improve overall energy performance while also offering builders more choices in achieving compliance. Understanding these specific updates is critical for anyone involved in residential construction.

Changes to Insulation Requirements

A significant area of update in the 2024 IECC relates to insulation, particularly for attics. Insulation plays a crucial role in preventing heat transfer, keeping homes warm in winter and cool in summer, and thereby reducing energy consumption. The prescriptive attic insulation requirements have been adjusted in the new code. These prescriptive requirements specify a minimum R-value, which is a measure of thermal resistance, that insulation must meet.

Reduced Prescriptive Attic Insulation

One of the most notable changes is that the prescriptive attic insulation requirements have been reduced by R-11 across all climate zones. This means that, under the prescriptive path, the specified R-value for attic insulation is now R-11 lower than what was required in the 2021 IECC. For example, if a climate zone previously required R-60 attic insulation, it might now only require R-49 under the prescriptive path. This change, mentioned in an overview of the 2024 IECC for residential construction, is a key update for builders to consider when planning their insulation strategies. While a reduction in a prescriptive requirement might seem counterintuitive to increasing energy efficiency, it is important to understand that the IECC offers multiple compliance paths. Builders often have the option to use a performance path, which allows for trade-offs between different energy-saving measures, as long as the overall building achieves the required energy performance. This reduction in prescriptive attic insulation requirements by R-11 across all climate zones (see table below) is one of the most significant changes from the 2021 IECC. This allows for greater flexibility in design and construction methods, especially when combined with other energy-saving measures.

Broader Impact on Residential Construction

These updates to insulation requirements are part of a larger trend within the 2024 IECC to make energy performance targets more challenging while simultaneously increasing flexibility. Builders are encouraged to look at the entire building envelope and systems as a whole to achieve the required energy savings. This could involve optimizing other elements like windows, air sealing, or HVAC systems to compensate for changes in insulation values. For HERS Raters, these adjustments mean a need to be thoroughly familiar with the new prescriptive tables and the updated performance modeling guidelines. Their role in verifying compliance will involve confirming that the chosen insulation levels, whether prescriptive or part of a performance package, meet the code's intent. The goal is to ensure that residential buildings continue to achieve high levels of energy efficiency, adapting to new technologies and construction methods. The 2024 IECC provides new opportunities and challenges for builders as they navigate these updated requirements.

Which Jurisdictions are Adopting the 2024 IECC?

The 2024 International Energy Conservation Code (IECC) is a model code, meaning it provides a framework that individual states, counties, and cities can choose to adopt. This document forms the foundation for many local energy codes across the United States. Its widespread adoption indicates a national trend toward improved building energy efficiency.

States and Cities Leading Adoption

Many jurisdictions across the country are in the process of adopting or have already adopted the 2024 IECC. This includes a diverse range of states and major metropolitan areas. For instance, cities like Phoenix, Arizona, and Austin, Texas, are listed among the adopting jurisdictions. States such as Colorado, Illinois, Nevada, New York State, North Dakota, Rhode Island, and Utah are also incorporating the 2024 IECC into their building regulations. Other specific localities like Clark County and Las Vegas in Nevada, and Nashville and Davidson County in Tennessee, have also moved to adopt the code. This broad geographical spread highlights the influence of the IECC as the national model energy code for low-rise residential buildings.

Adoption with Amendments

It is important to note that jurisdictions often adopt the IECC with amendments. This means that while the core framework of the 2024 IECC is used, specific provisions may be modified, added, or removed to better suit local climate conditions, economic factors, or policy goals. For example, both Colorado and Utah are listed as adopting the IECC 2024 with amendments. This practice allows states and cities to tailor the energy code to their unique needs while still benefiting from the comprehensive research and development that goes into the national model code. Builders and HERS Raters operating in these areas must be aware not only of the general IECC 2024 provisions but also of any specific local amendments that apply to their projects. This ensures full compliance and avoids potential delays or rework. The IECC 2024, combined with local jurisdiction amendments, forms the state codes.

The Impact of Adoption

The adoption of the 2024 IECC by numerous jurisdictions signifies a collective commitment to reducing energy consumption in new construction. As more states and cities implement this code, it will drive a greater demand for energy-efficient building materials, technologies, and practices. This, in turn, helps to standardize construction practices across regions, making it easier for builders to understand and comply with energy requirements. For homeowners, widespread adoption means that new homes, regardless of location, are more likely to be built to a higher standard of energy performance, leading to long-term savings on utility costs and a reduced environmental footprint. The IECC 2024 will be the benchmark for many states, counties, and municipalities moving forward, making its adoption crucial for the future of energy-efficient building.

How Does the 2024 IECC Impact Builders and HERS Raters?

The 2024 International Energy Conservation Code (IECC) brings both new opportunities and challenges for professionals in the building industry, particularly for homebuilders and Home Energy Rating System (HERS) Raters. The updated standards require a fresh look at construction practices and energy performance verification.

Importance for HERS Raters and Energy Code Professionals

For HERS Raters and other energy code professionals, understanding the updates to IECC 2024 is very important. These professionals are responsible for evaluating and verifying a building's energy performance against the code requirements. As the 2024 IECC introduces more challenging energy performance targets and new compliance pathways, HERS Raters must be thoroughly familiar with the revised provisions. This includes knowledge of updated insulation requirements, changes in air leakage targets, and new options for demonstrating overall building performance. Their expertise in interpreting and applying the code is crucial for ensuring that new homes meet the necessary energy efficiency standards. The 2024 IECC will serve as the benchmark for many states, counties, and municipalities, making continuous education and adaptation essential for these professionals.

New Opportunities and Challenges for Builders

The 2024 IECC presents a dual landscape of opportunities and challenges for builders. On one hand, the code's incrementally higher energy savings targets mean that builders must adapt their designs and construction methods to meet these more stringent requirements. This might involve investing in new materials, technologies, or training for their crews. On the other hand, the residential provisions of the 2024 IECC offer substantially more flexibility and a wider range of options for builders to achieve compliance. This flexibility can be an opportunity for innovation, allowing builders to explore cost-effective solutions and optimize their building processes. For example, changes like the R-11 reduction in prescriptive attic insulation requirements across all climate zones might encourage builders to explore different combinations of envelope improvements or more efficient HVAC systems to achieve overall performance targets. The new energy code aims to prioritize cost-effectiveness and consumer benefits, ensuring that energy-efficient homes are also economically viable for both builders and buyers. It also seeks to maximize design choices for builders, allowing them to maintain aesthetic and functional appeal while meeting efficiency goals. Critically, the code is designed so it can be practically implemented in the field, reducing potential barriers to adoption and compliance.

Prioritizing Cost-Effectiveness and Practical Implementation

The development of the 2024 IECC involved significant input from groups like the National Association of Home Builders (NAHB). NAHB staff and builder members worked to ensure the new energy code would prioritize cost-effectiveness and consumer benefits. This means the code aims for energy savings that provide a good return on investment for homeowners, without imposing excessive costs on builders. Furthermore, efforts were made to maximize design choices for builders, allowing them to continue building diverse and appealing homes while meeting efficiency standards. A key focus was also on practical implementation in the field. This means the code's requirements are designed to be achievable with current construction practices and readily available materials, minimizing the need for specialized equipment or highly complex procedures. This practical approach helps ensure that the code can be widely adopted and successfully applied across the industry, leading to real-world energy savings.

How Does the IECC Intersect with ENERGY STAR and HUD Loan Qualifications?

The 2024 International Energy Conservation Code (IECC) does not exist in a vacuum; its updates have implications for other significant energy efficiency initiatives, including the ENERGY STAR program and qualifications for Housing and Urban Development (HUD) loans. These intersections are important for builders and homeowners seeking to maximize the benefits of energy-efficient construction.

The Role of ENERGY STAR in New Construction

ENERGY STAR is a voluntary program of the United States government that promotes energy efficiency in products, homes, and buildings. The ENERGY STAR Residential New Construction Program offers certification for new homes and apartments that meet stringent energy efficiency guidelines. These guidelines often exceed the minimum requirements set by the IECC. For a home to earn ENERGY STAR certification, it must be significantly more energy-efficient than a standard home built to code. This typically involves a combination of features such as improved insulation, high-performance windows, efficient heating and cooling systems, and comprehensive air sealing.

Synergy Between IECC and ENERGY STAR

The updates within the 2024 IECC, while setting baseline requirements, also influence the landscape for programs like ENERGY STAR. As the IECC's minimum standards rise, the bar for what constitutes "standard" construction also increases. This means that ENERGY STAR certified homes will continue to push beyond these new code requirements, offering even greater energy savings. For builders, understanding the 2024 IECC is a foundational step. Achieving compliance with the IECC often puts them in a stronger position to pursue ENERGY STAR certification, which can add significant market value to their homes. ENERGY STAR certified homes are designed to use less energy, which translates to lower utility bills and a reduced carbon footprint for homeowners. The program provides clear, verifiable standards for energy-efficient new homes and apartments. The 2024 IECC updates have implications for key Energy Efficiency initiatives like ENERGY STAR.

Implications for HUD Loan Qualifications

While the research does not directly detail the specific impacts of the 2024 IECC on HUD loan qualifications, it is generally understood that federal housing programs, including those administered by HUD, often encourage or require certain levels of energy efficiency. Homes that meet or exceed current energy codes, and especially those that achieve certifications like ENERGY STAR, may be viewed more favorably. Energy-efficient homes typically have lower operating costs, which can improve a homeowner's debt-to-income ratio and overall financial stability, factors often considered in loan underwriting. Therefore, builders constructing homes to the 2024 IECC standards, and particularly those aiming for ENERGY STAR certification, may find that their properties are more attractive for buyers seeking HUD-backed financing. The intersection of the 2024 IECC with these initiatives underscores the holistic approach to promoting sustainable and affordable housing through energy efficiency. ENERGY STAR offers certification for energy-efficient new homes and apartments, and it is an official program of the United States government.

What is the Future of Energy Codes Beyond 2024?

The development of energy codes is a continuous process, driven by the ongoing need to improve building performance, reduce energy consumption, and adapt to new technologies. Even as the 2024 International Energy Conservation Code (IECC) is being adopted, work is already underway to shape the next iteration of these crucial standards.

The 2027 IECC: Already in Development

The International Code Council (ICC) operates on a three-year cycle for updating the IECC. This means that immediately following the release and adoption phase of one edition, the process for developing the next begins. Work is already underway to develop the next edition of the code, the 2027 IECC. This proactive approach ensures that energy codes remain current and responsive to advancements in building science and evolving energy goals. The committees responsible for developing the code are continuously evaluating new research, technologies, and feedback from the field to inform future requirements. This cycle of continuous improvement is essential for maintaining the IECC's relevance and effectiveness as the national model energy code.

Sustained Involvement from Industry Stakeholders

Key industry organizations, such as the National Association of Home Builders (NAHB), maintain active involvement in the code development process. NAHB was represented on both the commercial and residential committees for the 2024 IECC, with builder members and staff dedicating significant time to ensure the code's practical implementation, cost-effectiveness, and consumer benefits. These individuals continue their work on these bodies to develop the next edition of the code, the 2027 IECC. This sustained engagement from builder organizations helps to ensure that future codes are not only ambitious in their energy-saving goals but also realistic and achievable for the construction industry. Their input helps balance the push for higher efficiency with the practical considerations of building homes in diverse markets. The goal is to develop codes that maximize design choices for builders while remaining practical to implement in the field.

Driving Towards Higher Performance and Sustainability

The trajectory of energy codes is consistently towards higher performance and greater sustainability. Future editions of the IECC, including the 2027 version, are expected to continue this trend, pushing for even greater energy savings and potentially incorporating new considerations related to carbon emissions, grid interaction, and advanced building systems. The 2024 IECC already achieves a 7.8% site energy savings and 6.6% energy cost savings compared to the 2021 edition, setting a new benchmark. The ongoing development process allows for the integration of innovative solutions and addresses emerging challenges in the built environment. This forward-looking approach ensures that energy codes remain a vital tool in the broader effort to create more energy-efficient and environmentally responsible buildings for the future.

Frequently Asked Questions

What is the primary purpose of the International Energy Conservation Code (IECC)?

The primary purpose of the International Energy Conservation Code (IECC) is to set minimum energy efficiency standards for new construction. It covers various building components like walls, floors, ceilings, lighting, windows, doors, duct leakage, and air leakage. The goal is to ensure new buildings are constructed to reduce energy consumption, with the 2024 IECC achieving 7.8% site energy savings compared to the 2021 edition.

How often is the IECC updated?

The International Energy Conservation Code (IECC) is updated every three years by the International Code Council (ICC). This regular cycle ensures the code remains current with advancements in building science, technology, and energy conservation practices. The 2024 IECC is the latest edition, and work is already underway for the 2027 IECC.

What specific energy savings does the 2024 IECC offer compared to the 2021 edition?

The U.S. Department of Energy (DOE) determined that the 2024 IECC achieves 7.8% site energy savings and 6.6% energy cost savings compared to the previous 2021 IECC edition. These savings demonstrate the continuous improvement in energy efficiency standards set by the code, leading to lower energy consumption and costs for homeowners.

Are there any changes to insulation requirements in the 2024 IECC?

Yes, the 2024 IECC includes changes to insulation requirements, specifically for attics. The prescriptive attic insulation requirements have been reduced by R-11 across all climate zones. This change, while seemingly a reduction, is part of a broader strategy to offer builders more flexibility in achieving overall energy performance targets through various compliance options.

Which states have adopted the 2024 IECC?

Several states and cities are adopting the 2024 IECC, often with local amendments. Adopting jurisdictions 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. This widespread adoption establishes the 2024 IECC as a national benchmark for energy efficiency in new construction.