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Q: What is the difference between IECC and ENERGY STAR?

The IECC is a model building code that sets *minimum* energy efficiency standards for new construction, covering elements like walls, floors, and air leakage. ENERGY STAR, on the other hand, is a *voluntary* U.S. government program that certifies homes for achieving energy efficiency levels significantly *above* the minimum code requirements. While the IECC provides a baseline, ENERGY STAR pushes for higher performance.

Last updated: April 2026

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Quick Answer

The 2024 International Energy Conservation Code (IECC) is the latest model energy code, updated every three years by the International Code Council (ICC).
It achieves a 7.8% site energy savings and 6.6% energy cost savings compared to the previous 2021 IECC edition.
The new code offers more flexibility for builders to meet compliance targets in residential construction, providing a wider range of options.
Prescriptive attic insulation requirements have been reduced by R-11 across all climate zones, which is a significant change for builders.

The 2024 International Energy Conservation Code (IECC) represents an important step forward in setting minimum efficiency standards for new construction across the United States. Developed by the International Code Council (ICC), this model building code is updated every three years and is widely recognized as the national standard for low-rise residential buildings. The U.S. Department of Energy (DOE) has determined that the 2024 IECC achieves a 7.8% site energy savings and 6.6% energy cost savings when compared to the 2021 IECC. This newest edition provides builders with more flexibility and a wider range of options to achieve compliance, even as overall energy performance targets have become more challenging. Understanding these updates is crucial for anyone involved in home energy audits, efficiency upgrades, and new home construction.

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

The 2024 International Energy Conservation Code (IECC) is a foundational document that sets minimum energy efficiency standards for new construction. It is created by the International Code Council (ICC) and serves as a model building code. The IECC helps ensure that new homes and commercial buildings are constructed to specific energy performance levels, impacting everything from the building envelope to mechanical systems. This code is critical for driving energy efficiency improvements across the construction industry.

History and Purpose of the IECC

The International Energy Conservation Code was first created in 2000. Since its inception, it has become the industry standard for energy codes in the United States. The ICC updates the code every three years, ensuring it stays current with advancements in building science and energy efficiency technologies. The main purpose of the IECC is to establish minimum efficiency standards for new construction. These standards cover a broad range of building components. They include a structure’s walls, floors, ceilings, lighting, windows, doors, duct leakage, and air leakage. By setting these standards, the IECC aims to reduce energy consumption in buildings, leading to lower utility bills for occupants and a smaller environmental footprint. It is widely adopted across the country and is recognized as the national model energy code for low-rise residential buildings.

How Model Codes Influence Local Standards

The IECC acts as a model code, meaning it provides a template that states, counties, and municipalities can adopt. Many code offices across the USA have adopted the IECC. Local jurisdictions often combine the IECC 2024 with their own amendments to form their specific state or city codes. This process means that while the IECC sets a national baseline, the exact requirements can vary depending on where a building is located. For HERS Raters and energy code professionals, understanding these updates is very important. The 2024 IECC will be the benchmark for many states, counties, and municipalities moving forward. It influences how energy audits are performed and what efficiency upgrades are considered standard for new construction. The continuous updates every three years reflect an ongoing commitment to improving building energy performance. This evolution ensures that new buildings are increasingly efficient over time, contributing to broader energy conservation goals. The code offers residential provisions that provide flexibility and options for builders.

Scope of the 2024 IECC

The 2024 IECC covers both residential and commercial energy efficiency. For residential buildings, it includes detailed chapters on scope and administration, definitions, general requirements, and residential energy efficiency. It also features various appendices that address specific aspects like solar-ready provisions, zero net energy residential building provisions, electric energy storage, and electric vehicle charging infrastructure. These appendices offer additional guidance and requirements for builders looking to incorporate advanced energy features. The code's comprehensive nature means it touches almost every aspect of a new home's energy performance. This ranges from the insulation in the attic to the airtightness of the building envelope. The goal is to create smarter, more energy-efficient homes.

How Does the 2024 IECC Improve Energy Efficiency?

The 2024 International Energy Conservation Code (IECC) brings significant improvements in energy efficiency compared to its previous editions. These improvements are designed to reduce overall energy consumption and costs for homeowners. The code achieves this through updated performance targets and increased flexibility in compliance pathways.

Quantifiable Energy and Cost Savings

The U.S. Department of Energy (DOE) conducted a determination on the 2024 IECC. This analysis showed clear benefits. The 2024 IECC achieves a 7.8% site energy savings compared to the previous edition, the 2021 IECC. Additionally, it achieves 6.6% energy cost savings when compared to the 2021 IECC. These figures highlight the tangible benefits of adopting the new code. For homebuilders and homeowners, these savings translate into lower operational costs over the lifetime of a building. Site energy savings refer to the energy consumed directly at the building, while energy cost savings reflect the reduction in utility bills. This determination from the DOE provides concrete evidence of the code's effectiveness in promoting energy efficiency. We see these improvements as a direct result of the updated standards and requirements outlined in the 2024 IECC.

Increased Flexibility for Builders

One of the most significant changes in the residential provisions of the 2024 IECC is the increased flexibility it offers to builders. While the energy performance targets have generally gotten more challenging, the code provides a wider range of options for builders to achieve compliance. This means builders can choose from various strategies and technologies to meet the efficiency goals, allowing for more design choices and practical implementation in the field. The NAHB, the National Association of Home Builders, has stated that "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 flexibility is crucial for builders operating in diverse climates and markets, allowing them to adapt the code requirements to their specific projects and local conditions. This approach helps ensure that compliance is not overly burdensome while still pushing for higher energy performance.

Specific Efficiency Changes and Updates

The 2024 IECC includes several specific updates that contribute to its improved energy efficiency. One notable change is in ceiling insulation requirements. The prescriptive attic insulation requirements have been reduced by R-11 across all climate zones. This change, while seemingly a reduction, likely reflects a broader shift in how overall building envelope performance is calculated or allows for trade-offs in other areas to achieve the same or better overall energy performance. Understanding these 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. These professionals need to be aware of how these changes impact their energy modeling and inspection processes. The code's updates aim to prioritize cost-effectiveness and consumer benefits. They also maximize design choices for builders. The goal is to ensure the code can be practically implemented in the field. We analyze these changes to understand their full impact on home energy performance. For more details, Ekotrope's overview of 2024 IECC residential updates provides further insights into these specific residential updates.

The 2030 Glide Path and Future Goals

The 2024 IECC also includes appendices that look towards future energy goals. For example, Appendix CD, titled "The 2030 Glide Path," outlines provisions for commercial energy efficiency. Similarly, Resource CRB further details "The 2030 Glide Path (Prescriptive)" for commercial buildings. While these specific appendices focus on commercial structures, they indicate a broader trend towards achieving more ambitious energy performance targets in the long term. The continuous updates to the IECC every three years demonstrate a commitment to pushing the boundaries of energy efficiency in construction. This forward-looking approach ensures that the code remains relevant and effective in addressing evolving energy challenges and sustainability goals.

Which Jurisdictions are Adopting the 2024 IECC?

The 2024 International Energy Conservation Code (IECC) serves as a vital foundation for energy codes across the United States. Its adoption by various jurisdictions is a key indicator of its influence on new construction practices. States and local municipalities can choose to adopt the IECC as is, or they can modify it to suit their specific needs and local conditions.

The Role of the IECC in State and Local Codes

The IECC 2024 is a code produced by the International Code Council (ICC). This document provides the foundation for many state and city codes. States and local jurisdictions often combine the IECC 2024 with their own amendments to form their specific state codes. This means that while the IECC offers a national baseline for energy efficiency, the exact regulations that builders must follow can vary. Understanding these local amendments is crucial for anyone involved in the building industry, especially HERS Raters and energy code professionals. These professionals must stay informed about the specific version of the code adopted in their operating area. They must also know any local modifications. The IECC is the most adopted energy code in the country, recognized as the national model energy code for low-rise residential buildings. Its widespread influence means that changes in the IECC have a ripple effect across the nation, impacting how homes are built and how they perform.

States and Cities Adopting the 2024 IECC

Several states and cities are adopting the 2024 IECC, with some jurisdictions incorporating amendments. This demonstrates the code's relevance and the ongoing effort to improve energy efficiency in new construction. 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. Some of these jurisdictions, like Colorado and Utah, are adopting the IECC 2024 with amendments. This highlights the flexibility of the model code, allowing local authorities to tailor it to their unique climate, economic, and policy goals. For builders and energy professionals, knowing which specific version of the code has been adopted in their area, including any amendments, is essential for ensuring compliance. The UpCodes website tracks the adoption of the Energy Code, 2024 (IECC 2024) by various jurisdictions, providing valuable information on where and how the code is being implemented across the country. You can check specific adoption details at Energy Code, 2024 (IECC 2024) | UpCodes.

Implications for Builders and HERS Raters

For builders, the adoption of the 2024 IECC means new standards and requirements for their projects. They need to understand the updates to ensure their construction practices meet the latest efficiency mandates. The code aims to prioritize cost-effectiveness and consumer benefits, while also maximizing design choices for builders. This means that while efficiency targets are higher, the pathways to achieve them are more flexible. For HERS Raters and energy code professionals, the 2024 IECC will serve as a new benchmark. They will need to update their knowledge and tools to accurately assess and verify compliance with the new code. This includes understanding the changes in prescriptive requirements, such as the reduction in attic insulation R-values, and how these changes interact with overall building performance calculations. The ongoing training and education for these professionals are critical to successfully implement the 2024 IECC across different jurisdictions. The code's development also involves continuous work on future editions, like the 2027 IECC, underscoring the dynamic nature of energy codes.

What are the Key Residential Updates in the 2024 IECC?

The 2024 International Energy Conservation Code (IECC) introduces several significant updates specifically for residential buildings. These changes aim to enhance energy performance while providing builders with more adaptable compliance pathways. Understanding these updates is crucial for anyone involved in designing, building, or assessing new homes.

Shifting Energy Performance Targets

Overall, the energy performance targets in the 2024 IECC have become more challenging compared to previous editions. This means that new residential buildings are expected to achieve higher levels of energy efficiency. The U.S. Department of Energy (DOE) determined that the 2024 IECC achieves a 7.8% site energy savings and 6.6% energy cost savings compared to the 2021 IECC. These increased targets push the industry towards more sustainable construction practices. Builders must now focus on optimizing various aspects of a home's design and construction to meet these stricter requirements. This includes careful consideration of the building envelope, heating and cooling systems, water heating, and lighting. The goal is to create homes that consume less energy, reducing both environmental impact and homeowner utility costs. The continuous evolution of the IECC reflects an ongoing commitment to advancing energy efficiency in the residential sector.

Enhanced Flexibility in Compliance

Despite the more challenging performance targets, the 2024 IECC offers substantially more flexibility and a wider range of options for builders to achieve compliance. This is a key theme of the new residential provisions. Builders can explore different strategies, such as improving insulation beyond prescriptive requirements, installing more efficient HVAC systems, or incorporating renewable energy sources. This flexibility allows builders to choose the most cost-effective and practical solutions for their specific projects and climate zones. For example, if certain prescriptive requirements are difficult to meet, builders might be able to make trade-offs by exceeding efficiency in other areas of the home. This approach moves away from a rigid, one-size-fits-all model towards a performance-based framework that encourages innovation. The NAHB highlights this, stating that the residential provisions "will offer substantially more flexibility and a wider range of options for builders to achieve compliance." This flexibility is designed to make the code more practical for implementation in the field.

Notable Changes to Building Components

One of the most specific and notable updates in the 2024 IECC for residential buildings concerns ceiling insulation requirements. The prescriptive attic insulation requirements have been reduced by R-11 across all climate zones. This change might seem counterintuitive for an energy code aiming for higher efficiency. However, it likely reflects a holistic approach to building performance, where improvements in other areas or the overall performance method allow for this adjustment. For instance, enhanced airtightness or more efficient windows might compensate for a slightly lower attic R-value, as long as the overall energy target is met. Builders and HERS Raters need to understand how this specific change integrates with the broader energy performance calculations. The code also sets minimum efficiency standards for other critical components, including walls, floors, lighting, windows, doors, duct leakage, and air leakage. These standards collectively contribute to the home's overall energy efficiency. The IECC 2024 also offers appendices like "Solar-Ready Provisions" and "Electric-Ready Residential Building Provisions," encouraging the integration of renewable energy and future-proofing homes. You can find the full details of these provisions in the 2024 International Energy Conservation Code (IECC).

Prioritizing Cost-Effectiveness and Practicality

The development of the 2024 IECC involved significant effort to ensure that the new energy code prioritizes cost-effectiveness and consumer benefits. This means that the code aims to implement changes that provide a good return on investment for homeowners through energy savings, without imposing excessive upfront costs on builders. Furthermore, the code seeks to maximize design choices for builders. This allows them to maintain aesthetic and functional variety in their homes while still meeting efficiency goals. The emphasis on practical implementation in the field ensures that the code's requirements are achievable using current construction techniques and available materials. These considerations are vital for the widespread adoption and successful implementation of the IECC. The updates are designed to challenge the industry to build more efficiently, but in a way that is both economically viable and adaptable to real-world building scenarios.

How Does the IECC Impact ENERGY STAR Certification?

The International Energy Conservation Code (IECC) and the ENERGY STAR certification program both aim to improve energy efficiency in homes. While they serve different purposes, the updates in the 2024 IECC have a direct impact on how homes can achieve ENERGY STAR certification. Understanding this relationship is important for builders and homeowners pursuing high-performance homes.

IECC as a Baseline for Energy Performance

The International Energy Conservation Code (IECC) sets minimum efficiency standards for new construction. It covers a structure’s walls, floors, ceilings, lighting, windows, doors, duct leakage, and air leakage. This makes the IECC a fundamental baseline for energy performance in new homes. All new homes built in jurisdictions that have adopted the IECC must meet these minimum standards. The 2024 IECC, with its determined 7.8% site energy savings and 6.6% energy cost savings compared to the 2021 IECC, raises this baseline. This means that newly constructed homes are becoming inherently more efficient even before additional certifications are considered. The IECC ensures a basic level of energy performance across the board, which is a critical starting point for any further efficiency initiatives.

ENERGY STAR: Going Beyond the Code

ENERGY STAR is a voluntary program of the U.S. government that promotes energy efficiency. Homes that earn the ENERGY STAR label are independently verified to be more energy-efficient than homes built to minimum code standards. To achieve ENERGY STAR certification, homes must meet specific program requirements that often exceed the baseline set by the IECC. This means that while the IECC sets the floor for energy performance, ENERGY STAR aims for a higher level of achievement. The ENERGY STAR Residential New Construction Program provides detailed guidelines for builders to construct homes that are significantly more energy-efficient. These homes typically include features like better insulation, high-performance windows, efficient heating and cooling systems, and improved airtightness. The goal of ENERGY STAR is to help consumers identify and purchase homes that offer superior energy performance and lower utility bills. You can learn more about the program at the ENERGY STAR Residential New Construction Program page.

The Interplay Between IECC and ENERGY STAR

The updates in the 2024 IECC directly affect the path to ENERGY STAR certification. As the IECC's minimum standards become more stringent, the gap between code-built homes and ENERGY STAR certified homes may shift. For example, if the IECC now requires higher insulation levels or tighter building envelopes, homes built to code will already be closer to ENERGY STAR requirements. This can make it easier or less costly for builders to achieve the ENERGY STAR label. Conversely, ENERGY STAR often updates its own requirements to maintain its distinction as a high-performance benchmark. The 2024 IECC will be the benchmark for many states, counties, and municipalities moving forward, and its intersection with key Energy Efficiency initiatives like ENERGY STAR is important for energy code professionals. Builders aiming for ENERGY STAR homes must meet specific program requirements, which are often verified by a third-party Home Energy Rater. The ENERGY STAR program emphasizes a whole-house approach to energy efficiency, ensuring that all components work together to deliver optimal performance. For more information on what makes a home ENERGY STAR certified, visit the ENERGY STAR Certification page.

Benefits for Homeowners and the Market

Homes that are both code-compliant under the 2024 IECC and ENERGY STAR certified offer significant benefits to homeowners. These homes typically have lower energy bills, improved comfort, and enhanced durability. The combination of mandatory code compliance and voluntary certification creates a market for high-performance homes that are both efficient and reliable. ENERGY STAR certified homes are recognized for their superior energy performance. This recognition helps consumers make informed decisions when purchasing a new home. The program ensures that homes are built to a higher standard, providing long-term value and savings. The U.S. government supports the ENERGY STAR program, ensuring its credibility and widespread acceptance. Official websites use .gov, and secure .gov websites use HTTPS, indicating a reliable source for information on energy-efficient new homes and apartments. You can explore more about energy-efficient new homes and apartments at Energy Efficient New Homes and Apartments.

What Role Does NAHB Play in IECC Development?

The National Association of Home Builders (NAHB) plays a significant and active role in the development of the International Energy Conservation Code (IECC). Their involvement is crucial in ensuring that the code is not only effective in promoting energy efficiency but also practical, cost-effective, and flexible for builders to implement in real-world construction scenarios.

Advocacy and Representation in Code Development

The International Code Council (ICC) develops the IECC. The NAHB is represented on the committees responsible for this development. A small group of NAHB builder members and NAHB staff devote significant time and effort to this process. Their primary goal is to ensure that the new energy code prioritizes cost-effectiveness and consumer benefits. This means advocating for standards that lead to tangible energy savings for homeowners without imposing overly burdensome costs on builders. They also work to maximize design choices for builders, ensuring that energy efficiency requirements do not unduly restrict architectural styles or functional layouts. This advocacy helps to strike a balance between aggressive energy efficiency goals and the practical realities of home construction. The NAHB's continuous presence on these bodies helps shape the direction of energy codes for future editions, including the 2027 IECC.

Ensuring Practical Implementation

One of the key focuses of NAHB's involvement is to ensure that the IECC can be practically implemented in the field. This means that the code's requirements should be achievable using available technologies, materials, and construction techniques. They work to prevent the inclusion of provisions that might be technically challenging, excessively expensive, or difficult for builders to execute on a large scale. By providing a builder's perspective, NAHB helps to bridge the gap between theoretical energy efficiency targets and the realities of construction. For example, the 2024 IECC achieves a 7.8% site energy savings and 6.6% energy cost savings compared to the 2021 IECC. The residential provisions of this code offer substantially more flexibility and a wider range of options for builders to achieve compliance. This flexibility is a direct result of efforts to make the code more adaptable and practical for builders.

Influence on Residential Provisions

The NAHB's influence is particularly strong in the residential provisions of the IECC. They work to ensure that updates, such as changes in ceiling insulation requirements or air leakage standards, are well-considered and balance efficiency gains with practical application. The organization aims to create a code that supports a competitive housing market while still pushing for higher energy performance. Their involvement helps shape aspects like the prescriptive attic insulation requirements, which have been reduced by R-11 across all climate zones in the 2024 IECC. This kind of change, while specific, reflects the ongoing dialogue between code developers and industry stakeholders to refine energy efficiency standards. The NAHB's role is not just about resisting change, but about guiding it towards solutions that benefit both the industry and the consumer. You can find more information about NAHB's advocacy and priorities regarding building codes on their website, specifically concerning the 2024 International Energy Conservation Code.

Looking Ahead to Future Code Editions

The NAHB's commitment extends beyond the current edition of the IECC. Their staff and builder members continue their work on these bodies to develop the next edition of the code, the 2027 IECC. This ongoing engagement ensures that the builder's perspective remains a consistent factor in the evolution of energy codes. By participating in the development process for future codes, the NAHB helps to anticipate challenges and opportunities. This proactive approach helps shape a regulatory environment that supports innovation and continuous improvement in home energy efficiency. Their efforts are crucial for creating energy codes that are effective, fair, and implementable for the residential construction industry.

Frequently Asked Questions

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 update cycle ensures that the code remains current with advancements in building science, energy efficiency technologies, and construction practices. The latest version, the 2024 IECC, builds upon previous editions to set new minimum efficiency standards for new construction.

What are the main benefits of the 2024 IECC?

The 2024 IECC offers significant benefits, including improved energy efficiency and cost savings for homeowners. The U.S. Department of Energy (DOE) determined that it achieves a 7.8% site energy savings and 6.6% energy cost savings compared to the 2021 IECC. It also provides builders with more flexibility and a wider range of options for achieving compliance, allowing for more adaptable construction practices.

Does the 2024 IECC apply to existing buildings?

The 2024 IECC primarily sets minimum efficiency standards for new construction. However, the code does include a Chapter 5 [RE] for "Existing Buildings" within its residential provisions. This chapter outlines requirements for energy efficiency improvements when renovations or additions are made to existing structures, but its primary focus is on new builds.

What is the difference between IECC and ENERGY STAR?

The IECC is a model building code that sets minimum energy efficiency standards for new construction, covering elements like walls, floors, and air leakage. ENERGY STAR, on the other hand, is a voluntary U.S. government program that certifies homes for achieving energy efficiency levels significantly above the minimum code requirements. While the IECC provides a baseline, ENERGY STAR pushes for higher performance.

Where can I find specific amendments to the 2024 IECC for my state?

The IECC 2024 provides a foundation, but many states and cities adopt it with their own local amendments. To find specific amendments for your state or city, you should consult your local building department or an online code resource like UpCodes. For example, jurisdictions such as Colorado and Utah are adopting the IECC 2024 with amendments, which means local deviations from the model code exist.