Energy Codes and Roofs: Information Guide
By Roof Online Staff • Last updated March 23, 2023
Energy Codes: Introduction to the IECC
When you’re talking about energy codes in the United States these days, you’re probably talking about the International Energy Conservation Code (IECC). There are other codes and standards that are used in some jurisdictions, but the IECC is the big one. (We mention some of the others below.)
The IECC is a model code produced by the International Code Council (ICC). Updated versions of the code are released every three years.
State and local jurisdictions adopt the code as they see fit, often amending or changing the text of the code, using it as the foundation of the actual codes that are in effect in any given area.
Because the IECC as released by the ICC is simply a model, and has no legal authority until it is actually adopted by a jurisdiction, which often entails modification, it is important to check which version of the code is currently in effect in your area, and what, if any, amendments have been added to it.
You can’t simply look up the code on the ICC website and be sure that the language in the latest version of the model code is the same as the language in the current energy code in your area.
The IECC sets minimum energy efficiency standards for new construction and renovations, such as roof replacement, of commercial and residential buildings. The code covers a range of topics related to building design and construction, including insulation, lighting, HVAC systems, and building envelopes.
Some of the sections of the 2021 IECC that may pertain to roofs and roofing include (click on the links to see the full text of the sections):
- Section C301: Climate Zones. This section defines the different climate zones used in the IECC and provides guidance on the design and construction requirements for each zone. The climate zones take into account factors such as temperature, humidity, and solar radiation and are used to determine the minimum energy efficiency requirements for different building components, including roofs.
- Section C402.1: General (Building thermal envelope). This section covers the requirements for the thermal envelope of buildings, which includes roofs, walls, floors, and fenestration (windows and doors). The section sets minimum R-value requirements for different climate zones and prescribes methods for calculating R-values and U-factors.
- Section C402.2: Roof insulation. This section specifically addresses roof insulation requirements, including the minimum R-values for different types of roofs and roof decks. The section also provides guidance on the installation of insulation and vapor barriers.
- Section C402.3: Solar reflectance. This section specifies minimum solar reflectance requirements for low-slope roofs in certain climate zones. The solar reflectance requirements are intended to reduce the amount of heat absorbed by the roof and mitigate the urban heat island effect.
- Section C402.5: Air leakage. This section covers the requirements for minimizing air leakage in the building envelope, including roofs. The section sets maximum allowable air leakage rates and provides guidance on air sealing techniques.
- Section C407: Total Building Performance. This section provides an optional compliance path for buildings that exceed the prescriptive requirements of the code. The section allows for performance-based calculations that take into account factors such as building orientation, shading, and the thermal properties of roofs and other building components.
Note that the specific requirements for roofs and roofing in the IECC may vary depending on the building type, climate zone, and other factors.
Other Energy Codes and Standards
Here are some examples of other energy codes in use in the United States:
- ASHRAE Standard 90.1: This is a commercial building energy standard developed by the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE). It covers a wide range of building systems and components, including HVAC, lighting, building envelope, and renewable energy. Many states include this standard in their commercial energy code.
- California Energy Code (Title 24): California has its own energy code that covers both residential and commercial buildings. The code is updated every three years and sets stringent energy efficiency requirements for building systems and components.
- International Green Construction Code (IgCC): The IgCC is a model code developed by the International Code Council (ICC) that sets standards for the design and construction of high-performance, sustainable buildings. The code covers a wide range of topics, including energy efficiency, water conservation, indoor air quality, and site design.
- State-specific energy codes: Some states have developed their own energy codes that are tailored to their specific climate, building practices, and energy goals. Examples include the Florida Energy Conservation Code and the Washington State Energy Code.
It is important to note that many of these codes are based on the same energy efficiency principles and may have similar requirements to the IECC. However, there may be some differences in the specific requirements and compliance paths. Building owners and designers should always verify which specific energy codes are in effect in their location.
- Building Codes and Roofs
- Building Insulation
- Cool Roofs (Reflective Roofing)
- Codes And Standards Organizations Relevant To Roofing
- How Your Roof Can Make Your Home More Energy Efficient
- R-Value and Roofs
External Sources & References for Energy Code Information
1. Recommended for Further Reading: 2021 International Energy Conservation Code (International Code Council Series)
2. General: “Minimum Insulation R-value Requirements Non-Residential, Above Roof Deck” is an extremely handy table for state and local jurisdictions in the United States. The document was updated in 2022 and is available on the Carlisle SynTec website. You may have to click on the preview button to get it to display properly.
3. General: (BCAP): Select your state on the home page of the Building Codes Assistance Project (BCAP) for US state energy code information. On this site you can find information regarding code status, guides to building energy codes, and more. The focus is on United States jurisdictions, but some useful international information is available as well.
4. General: (BCAP): Australia: The Australia page at the BCAP website.
5. General: (BCAP): Canada: The Canada page at the BCAP website.
6. General: (BCAP): India: The India page at the BCAP website.
7. General: (BCAP): Ireland: The Ireland page at the BCAP website.
8. General: (BCAP): New Zealand: The New Zealand page at the BCAP website.
9. General: (BCAP): United Kingdom: The United Kingdom page at the BCAP website.
10. General: See this up-to-date energy code information for individual US states at the National Roofing Contractors Association website. Note that some municipalities may have energy codes that differ from the state code; the NRCA website makes an effort to point out when this is the case.
12. Codes: The entire 2018 International Energy Conservation Code is viewable on the ICC website. Please note that the actual code in effect in your area may have been adopted with amendments.
14. Codes: Commercial Envelope Requirements of the 2018 IECC is an easy-to-follow guide to compliance. Always check with your local authority to determine which code is in effect in your area. This guide is made available by the US Department of Energy on the Building Energy Codes Program website.
15. Codes: Residential Provisions of the 2018 International Energy Conservation Code is an easy-to-follow guide to compliance. Always check with your local authority to determine which code is in effect in your area. This guide is made available by the US Department of Energy on the Building Energy Codes Program website.
16. Codes: Requirements of the 2012, 2015, 2018, and 2021 Residential and Commercial codes may be accessed from the Building Energy Codes Program’s “Training Courses“ page.