Skip to main content

This is the first of four blogs from the Window & Door Manufacturers Association (WDMA) entitled “The Residential Energy Code Series.” WDMA has created this series to share the history, development and future of the residential energy code and how a window, door and skylight’s performance will be impacted by the energy code.

Discover the world of residential energy codes and stay up to date on the up-and-coming series topics:

  • Part 1-History of the Residential Energy Code
  • Part 2-Energy Code Development Process
  • Part 3-State Energy Code Adoption
  • Part 4-Upcoming 2024 IECC

To learn more about WDMA and for access to additional content, please visit our articles page.


Photo Credit: JELD-WEN

The History of the Residential Energy Code

The International Energy Conservation Code (IECC) and its predecessor, the Model Energy Code (MEC) have been at the center of residential energy codes in the United States for over 40 years. The IECC is updated on a triennial schedule by the International Code Council (ICC) and is currently the basis for residential energy codes in 49 states (8 states only adopt energy codes locally) and the District of Columbia with only California adopting its own statewide version. The IECC has become a valued tool for governments and energy-efficiency advocates looking to mitigate climate change, reduce energy consumption, and promote sustainable practices in the construction and operation of buildings. The IECC is also referenced in federal statutes as a means to encourage states to continually improve the energy efficiency of residential construction.

The advent of energy codes in the United States can be traced back to the oil crisis of the 1970s when a global energy shortage compelled the US to address energy consumption in all sectors. In response, the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) developed their ASHRAE 90 Energy Efficiency Standard in 1975 that primarily addressed commercial construction.

The need for a residential energy efficiency code prompted a consortium of regional building code organizations (Council of American Building Officials (CABO), Building Officials and Code Administrators International, Inc. (BOCA), International Conference of Building Officials (ICBO), National Conference of States on Building Codes and Standards (NCSBCS), and Southern Building Code Congress International (SBCCI)) to collectively develop such an energy code. Along with funding from the Department of Energy (DOE), the consortium took the lead in developing its own residential energy code. In 1983 the Model Energy Code (MEC) became the first widely adopted residential energy code in the US. It has served as a voluntary code for states to implement energy-efficient practices in residential construction.

In 1998, the MEC was succeeded by the first edition of the IECC created by the newly formed ICC. The code introduced performance-based and prescriptive-based compliance paths, allowing flexibility for builders and designers to meet energy efficiency targets. Over the years, the IECC has experienced regular updates, providing consistent energy efficiency improvement for buildings constructed to the latest edition of the code.

To guarantee consistent efficiency improvements in the IECC, in 1994, the Energy Policy and Conservation Act (EPCA) was amended to include a process where the DOE compares the efficiency of a newly published edition of the MEC, (or its IECC successor) with that of the previous edition to determine if the newer version is more energy efficient. Originally signed into law by President Gerald Ford in 1975, the act sought to promote energy conservation and reduce dependence on foreign oil.


Photo Credit: Kolbe Windows & Doors

In addition to performing determinations on the energy code, the DOE also plays a crucial role in assisting both the development and implementation of energy efficiency standards in the United States. It uses the latest published edition of the IECC to decide whether states or local jurisdictions meet federal requirements for building energy codes. The DOE then evaluates states’ adoption and implementation of energy codes, and those that achieve compliance can be eligible for available incentives and funding opportunities.

While the U.S. does not technically have a national energy code; the widespread adoption and reference of the IECC in Federal statutes, makes the International Energy Conservation Code the preeminent residential energy code in the country. With aggressive efficiency and decarbonization goals by various governments and energy efficiency advocates, the IECC code update process receives considerable attention from groups affected by changes to the energy code.


Photo Credit: VELUX

Written by Craig Drumheller.

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

Webinar: Understanding Window, Door & Skylight Certification

Understand the benefits of window, door and skylight certification and how certified products can enhance your projects.

Register Now

Find Manufacturers

View our list of window, door, and skylight manufacturers. 

Find Manufacturers

Webinar: Understanding Window, Door & Skylight Certification

The Understanding Window, Door & Skylight Certification webinar is designed to help architects and remodelers understand the benefits of window, door and skylight certification and how certified products can enhance their projects.

Register Now

Find Manufacturers

Find window, door, and skylight manufacturers. 

Find Manufacturers