Energy Codes and Standards  

by Martha G. VanGeem
Revised and updated by Ryan M. Colker
Sustainable Buildings Industry Council



U.S. residential and commercial buildings account for approximately 41% of all energy consumption and 72% of electricity usage. The U.S. buildings sector alone accounted for 7% of global primary energy consumption in 2010. Total building primary energy consumption in 2009 was about 48% higher than consumption in 1980.1

Energy codes and standards set minimum efficiency requirements for new and renovated buildings, assuring reductions in energy use and emissions over the life of the building. As a building's operation and environmental impact is largely determined by upfront decisions, energy codes present a unique opportunity to assure savings through efficient building design, technologies, and construction practices. Once a building is constructed, it can be significantly more expensive to achieve higher efficiency levels. Including energy as a fundamental part of the building construction process and making early investments in energy efficiency yields benefits for all owners and occupants for years into the future.

Energy codes are a subset of building codes, which establish baseline requirements and govern building construction. Energy codes reference areas of construction such as wall and ceiling insulation, window and door specifications, HVAC equipment efficiency, and lighting fixtures.


Energy Code Formats

Today's energy codes come in two basic formats, prescriptive and performance. A possible third format, outcome-based, has begun to pique the interest of the building community.

  • A Prescriptive path is a fast, definitive, and conservative approach to code compliance. Materials and equipment must meet a certain levels of stringency, which are quantified in tables. These tables list the minimum and maximum requirements for the R- and U-values of materials, the allowable watts per square foot of lighting systems, and the minimum energy efficiencies required of mechanical systems. This path dictates specific requirements that must be met, but does not account for potentially energy saving features like window orientation.

  • Performance-based codes are designed to achieve particular results, rather than meeting prescribed requirements for individual building components. Performance paths typically are based on the anticipated results from application of the prescriptive path. This path is useful when quantifying non-traditional building features such as passive solar and photovoltaic technology. Performance-based approaches use an established baseline measurement from which certain systems must perform. This path requires more detail regarding building design, materials, and systems; however is a more flexible approach than the prescriptive path. Such an approach is particularly desirable for larger buildings, as it provides opportunities for trade-offs across energy-influencing systems to come up with the most cost-effective means for achieving compliance. Performance-based codes are technology neutral, thus enabling quicker incorporation of energy saving technologies and practices into the marketplace.

  • Outcome-based codes establish a target energy use level and provide for measurement and reporting of energy use to assure that the completed building performs at the established level. Such a code can have significant flexibility to reflect variations across building types and can even cover existing or historic buildings. Most importantly, it can address all energy used in buildings and provide a metric to determine the actual quality of the building construction.

Adoption of Energy Codes

The U.S. does not have a national energy code or standard, so energy codes are adopted at the state and local levels of government. Because of this, the codes and editions in place vary widely. The Department of Energy maintains information on energy codes adopted. DOE also provides technical assistance to states and localities as they adopt and enforce energy codes.

ANSI/ASHRAE/IES Standard 90.1 Energy Standard for Buildings Except Low-Rise Residential Buildings (commercial buildings) and the International Energy Conservation Code (commercial and residential buildings) are the most commonly adopted energy codes. Some jurisdictions, like California, have developed their own energy codes. Other codes and standards also have been developed including ASHRAE Standard 90.2 Energy Efficient Design of Low-Rise Residential Buildings. The NFPA has commercial and residential energy codes based on ASHRAE Standards 90.1 and 90.2 (NFPA 900 Building Energy Code and NFPA 5000 Building Construction and Safety Code®). These model codes and standards are typically updated on a three-year cycle, but actual time periods between their release and adoption varies widely. ANSI/ASHRAE/IES/USGBC Standard 189.1 Standard for the Design of High-Performance Green Buildings and the International Green Construction Code also include energy efficiency provisions for those wishing to go beyond minimum requirements.

In 1978, Congress passed legislation requiring states to initiate energy efficiency standards for new buildings. Since then, energy codes have undergone significant improvements. The 1992 Energy Policy Act ("EPAct") mandated that all states must review and consider adopting the national model energy standard. The Energy Policy Act of 2005 specified the most current model energy codes at the time of its passage (2004 IECC supplement, ASHRAE 90.1-2004). Requirements for states to implement review and update energy codes are triggered by release of new model codes and standards and a determination by DOE that the new codes and standards save energy (more discussion on this below). ANSI/ASHRAE/IES Standard 90.1-2010 and the 2012 International Energy Conservation Code (IECC) are the latest versions of the national model energy codes to receive positive determinations from DOE.

  • On October 19, 2011, DOE issued a final determination that ASHRAE Standard 90.1-2010 would achieve greater energy efficiency in buildings subject to the standard than if they were built to ASHRAE Standard 90.1-2007. View the complete final determination notice that appeared in the Federal Register on October 19, 2011

  • On May 17, 2012, DOE issued a final determination that the 2012 IECC would achieve greater energy efficiency in low-rise residential buildings than the previous editions of the IECC. View the complete final determination notice that appeared in the Federal Register on May 17, 2012

Left: US map of states that have adopted a statewide commercial energy code that meets or exceeds an ASHRAE 90.1 standard; Right: US map of states that have adopted a statewide residential energy code that meets or exceeds an IECC model code.

A national snapshot of building energy code adoption and implementation status.
Source: Building Codes Assistance Projects

DOE has developed tools to assist architects, builders, designers, and contractors in determining whether new commercial, high-rise residential buildings and homes, and additions and alterations meet the requirements of the IECC or ASHRAE Standard 90.1, as well as several state-specific codes. COMcheck and REScheck also simplify compliance for building officials, plan checkers, and inspectors by allowing them to quickly determine if a building project meets the code. Other Energy Analysis Tools can also assist in meeting and demonstrating compliance with energy codes.

Section 304 of the Energy Conservation and Production Act (Pub. L. No. 94-385), as amended by Section 101 of EPAct 1992, requires:

Commercial Buildings

(2)(A)Whenever the provisions of ASHRAE Standard 90.1-1989 (or any successor standard)regarding energy efficiency in commercial buildings are revised, the [DOE] Secretary shall, not later than 12 months after the date of such revision, determine whether such revision will improve energy efficiency in commercial buildings. The [DOE] Secretary shall publish a notice of such determination in the Federal Register.

(B)(i)If the [DOE] Secretary makes an affirmative determination under subparagraph (A), each State shall, not later than 2 years after the date of the publication of such determination, certify that it has reviewed and updated the provisions of its commercial building code regarding energy efficiency in accordance with the revised standard for which such determination was made. Such certification shall include a demonstration that the provisions of such State's commercial building code regarding energy efficiency meet or exceed such revised standard.

(ii)If the [DOE] Secretary makes a determination under subparagraph (A) that such revised standard will not improve energy efficiency in commercial buildings, State commercial building code provisions regarding energy efficiency shall meet or exceed ASHRAE Standard 90.1-1989, or if such standard has been revised, the last revised standard for which the [DOE] Secretary has made an affirmative determination under subparagraph (A).

Residential Buildings

(5)(A)Whenever CABO Model Energy Code**, 1992, (or any successor of such code) is revised, the [DOE] Secretary shall, not later than 12 months after such revision, determine whether such revision would improve energy efficiency in residential buildings. The [DOE] Secretary shall publish notice of such determination in the Federal Register.

(B)If the [DOE] Secretary makes an affirmative determination under subparagraph (A), each State shall, not later than 2 years after the date of the publication of such determination, certify that it has reviewed the provisions of its residential building code regarding energy efficiency and made a determination as to whether it is appropriate for such State to revise such residential building code provisions to meet or exceed the revised code for which the [DOE] Secretary made such determination.

* Council of American Building Officials (a predecessor to the ICC, CABO was responsible for development of the Model Energy Code [MEC]).

** [Early residential energy code revisions were referred to as the Model Energy Code; more contemporary energy codes are referred to as the International Energy Conservation Code® or IECC.]

Federal Building Energy Efficiency Requirements

Section 305 of ECPA, as amended2, requires DOE to establish building energy efficiency standards for all new Federal buildings. The standards must require energy efficiency measures that are technologically feasible and economically justified. The established standards must contain energy savings and renewable energy specifications that meet or exceed the energy savings and renewable energy specifications of the referenced voluntary consensus energy codes. Buildings must be designed to achieve energy consumption levels that are at least 30 percent below the levels established in the referenced codes, if life-cycle cost-effective. The referenced voluntary consensus code for commercial buildings (including multi-family high rise residential buildings) is the ANSI/ASHRAE/IES Standard 90.1 and the referenced code for low-rise residential buildings is the International Energy Conservation Code (IECC).

Not later than one year after the date of approval of each subsequent revision of the reference code or standard, DOE must determine whether to amend the Federal building standards with respect to the revised code or standard based on the cost-effectiveness of the revised code or standard.

The current Federal building energy efficiency performance standards are established in Parts 433 and 435 of title 10 of the Code of Federal Regulations.

Section 306(a) of ECPA, as amended3, provides that each Federal agency and the Architect of the Capitol must adopt procedures to ensure that new Federal buildings will meet or exceed the Federal building energy efficiency standards established under section 305. Section 306(b) bars the head of a Federal agency from expending Federal funds for the construction of a new Federal building unless the building meets or exceeds the applicable Federal building energy standards established under section 305.

Relevant Codes and Standards

Additional Resources


Systems & Specifications

Federal Green Construction Guide for Specifiers

Federal Government



Energy Design and Analysis Tools


1 [Department of Energy, Buildings Energy Data Book, 2011.]

2 [42 U.S.C. § 6834(a)]

3 [42 U.S.C. § 6835(b)]