Energy Codes

The energy consumed by residential and commercial buildings represents a significant portion of the total energy used in the United States. Energy drives the U.S. economy and demand will continue to grow along with prices and environmental concern. The reduction of building energy use through increased efficiency and conservation is important economically, environmentally and socially. Energy codes establish the minimum performance requirements for residential and commercial buildings and will play a key role in achieving national energy goals in the future. These codes will have an impact on the design, installation, operation and maintenance of electric power distribution, lighting and control systems. The electrical contractor needs to understand applicable energy codes in order to help customers meet their requirements.

State energy codes

Federal law mandates that each state have an energy code and establish minimum requirements for that code. It is up to each state to implement and enforce its own code that meets or exceeds the federal government requirements. There are also federal energy codes that apply only to government commercial and residential buildings.

Requiring states to develop energy codes makes sense because each state typically has different building practices as well as a different economy, environment and climate. Allowing states to develop their own energy code gives them the opportunity to tailor it to their own unique situation rather than trying to make “one size fit all.” However, the flip side is that each state can have its own energy code that is different than those that border it.

States have mostly adopted either ASHRAE Standard 90.1 or the International Energy Conservation Code (IECC) as the basis for their energy code.

ASHRAE Standard 90.1

The American Society of Heating, Refrigerating, and Air-Conditioning Engineers Inc. (ASHRAE) and the Illuminating Engineering Society of North America (IESNA) jointly sponsor ASHRAE/IESNA Standard 90.1, “Energy Standard for Buildings Except Low-Rise Residential Buildings” (ASHRAE 90.1). This standard was first published in 1975 and addressed both residential and commercial buildings.

In 1989, it was split into two standards with ASHRAE 90.1 covering commercial buildings and ASHRAE 90.2 covering low-rise residential buildings. ASHRAE 90.1 is on a three-year update cycle and the latest edition of ASHRAE 90.1 is the 2004 edition.

The purpose of ASHRAE 90.1 is stated in Section 1 of the standard: “to provide minimum requirements for the energy-efficient design of buildings except low-rise residential buildings.”

Low-rise residential buildings are defined as single-family houses and multifamily structures not exceeding three-stories above grade in Subsection 3.2. Therefore, ASHRAE 90.1 covers any building that does not meet the definition of a low-rise residential building. Building systems that use energy for industrial, manufacturing or commercial processes are not covered by ASHRAE 90.1 per Subsection 2.3c.

ASHRAE 90.1 is a consensus industry standard and compliance with it is voluntary unless mandated by law or contract. Since its original publication as ASHRAE 90 in the 1970s, a number of states adopted it as the basis for their energy code. As a result, the Energy Policy Act (EPACT) of 1992 required that all states adopt an energy code that was at least as stringent as ASHRAE 90.1-1989 or state why they cannot do it.

EPACT also gave the U.S. Department of Energy (DOE) the authority to review and adopt new editions of ASHRAE 90.1 as the minimum energy standard for the design and construction of commercial buildings in the United States. Because of EPACT, ASHRAE 90.1 is the basis for many states’ commercial building energy code as well as an alternative method of meeting the IECC.

International Energy Conservation Code

The IECC evolved from the Model Energy Code (MEC) that was developed by the Council of American Building Officials (CABO) and first published in 1983.

In 1998, the International Code Council (ICC)—which is made up of the Building Officials and Code Administrators International Inc. (BOCA), International Conference of Building Officials (ICBO) and the Southern Building Code Congress International (SBCCI)—took over the MEC and integrated it with its International Codes’ series as the IECC. Like ASHRAE 90.1, the IECC is updated every three years and the current edition is the 2003 IECC.

The scope of the IECC is stated in Subsection 101.2 as the establishment of “minimum prescriptive and performance-related regulations for the design of energy-efficient buildings and structures.”

The IECC covers both residential and commercial buildings. In fact, EPACT mandates that state energy codes for residential buildings meet the IECC requirements as a minimum similar to the EPACT requirement that ASHRAE 90.1 establish the minimum requirements for state commercial building energy codes.

IECC Chapters 7 and 8 address commercial buildings. Chapters 1, 2 and 3 provide important general requirements for commercial and residential buildings, address code administration, definitions and design conditions. Chapter 7 states in Subsection 701.1 that all commercial buildings must meet the requirements of ASHRAE 90.1, unless the design meets the requirements of IECC Chapter 8. Chapter 8 addresses requirements for the building envelope, mechanical systems, service water heating, electric power, lighting systems and total building performance.

Impact on electrical systems

Both ASHRAE 90.1 and IECC are focused on the building envelope and mechanical systems that have a major impact on building energy usage. However, lighting consumes a significant amount of energy in a commercial building and both ASHRAE 90.1 Section 9 and IECC Section 805 include specific requirements for both interior and exterior building lighting. Lighting power densities are specified, which affects light levels, lamp types and lighting equipment efficiency. Equally important to energy conservation are manual and automatic lighting controls and their operation that are required by both ASHRAE 90.1 and IECC.

While ASHRAE 90.1 and IECC deal almost exclusively with lighting, there are several other requirements that could impact an electrical installation. In Subsection 8.2.1, ASHRAE 90.1 requires that feeder and branch-circuit voltage drop not exceed 2 percent and 3 percent, respectively.

This is the same maximum voltage drop that is recommended, but not required, by the 2005 National Electrical Code in fine print notes (FPN) to paragraphs 210.19(A)(1), 215.2(A)(3), and 310.15(A)(1). ASHRAE Subsection 10.2 also includes a requirement that electric motors comply with EPACT and be energy efficient. In IECC Subsection 805.7, buildings with multiple individual dwelling units are required to have each dwelling unit individually metered.

Energy code adoption

States have adopted ASHRAE 90.1 or the IECC in total or with additions and modifications. Also, the latest editions of either ASHRAE 90.1 or the IECC do not automatically take effect when they are published. The edition that needs to be followed is the edition that is currently in force.

For example, the latest edition of ASHRAE 90.1 is the 2004 edition that was published last fall but no state has adopted it yet; the 1999 edition is still the DOE’s required minimum standard. In fact, some states are still using the 1989 and earlier editions of ASHRAE 90.1 as their commercial energy code. Similarly, some states are using earlier editions of the IECC, and a few states are even still using editions of the MEC as their residential energy code. Several states still do not have an energy code. EC

GLAVINICH is an associate professor in the Department of Civil, Environmental and Architectural Engineering at The University of Kansas and is a frequent instructor for NECA’s Management Education Institute. He can be reached at 785.864.3435 or 


About the Author

Thomas E. Glavinich

Freelance Writer
Thomas E. Glavinich was an associate professor in the Department of Civil, Environmental and Architectural Engineering at the University of Kansas. His tenure as one of Electrical Contractor's most trusted and reliable source of industry research end...

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