Idaho Energy Code Overview: Commercial

Idaho's current commercial energy code is based on the 2015 International Energy Conservation Code (IECC). Full versions of the IECC are available on the International Code Council's website

The 2015 commercial IECC became effective January 1, 2018.

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Commercial Energy Code

The commercial energy code applies to all buildings except those defined as residential, including one- and two-family homes, and R-2, R-3, and R-4 buildings three stories or less in height. The code applies to new construction, as well as additions, alterations, renovations, and repairs of existing structures. 

Any non-conditioned space that is altered to become conditioned space, such as heating an unfinished basement, must also fully comply with the code, as well as any buildings or spaces with a change in occupancy that results in an increase in energy. 

For buildings with a mixed occupancy, the residential portion must comply with the residential requirements and the commercial portion must comply with the commercial requirements. 

Code Provisions

The commercial energy code has provisions pertaining to a building's thermal envelope, mechanical system, service water heating, and lighting system. Mandatory requirements are included for:

2012 International Energy Conservation Code Climate Zone Map

2012 International Energy Conservation Code Climate Zone Map

  • Air leakage
  • Heating and cooling loads
  • Equipment sizing and performance
  • HVAC controls
  • Ventilation
  • Duct and piping insulation
  • Duct sealing
  • Service hot water heating
  • Lighting

Some requirements vary by climate zone, including those for:

  • Roofs
  • Above grade walls
  • Foundations (basements, slabs, crawlspaces)
  • Fenestration (skylights, windows, doors)
  • Simple and Complex HVAC systems and equipment

Idaho has jurisdictions in climate zones 5 and 6. 

Compliance Options

There are four options for complying with the commercial energy code: prescriptive, COMcheck, and performance and Standard 90.1. 

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  • Sections C402 - C406
  • Mandatory provisions must be met
  • No trade-offs permitted
  • No software tools needed

COMcheck / Total UA Alternative

  • Section R402.1.4
  • Mandatory provisions must be met
  • U-factor and assembly area used to determine trade off
  • COMcheck or approved method


  • Section C407
  • Mandatory provisions must be met
  • Simulated energy performance analysis comparing annual energy cost


  • The 2015 IECC allows alternative design with ASHRAE Standard 90.1 - 2013



Additional Efficiency Compliance Options

One additional efficiency feature must be selected to comply with the prescriptive requiresments of the commercial energy code. 

  • More efficient lighting
  • More efficient HVAC system
  • Installation of onsite renewables

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Code Specific Questions

For questions about specific code requirements, visit the resource page, check the Frequently Asked Questions, or contact us