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State Profile

Code Type: Commercial Residential
Current State Code 2018 IECC and ASHRAE 90.1-2016 2018 IECC with Amendments
Effective Date
Adoption Date
State Amendments No Yes
State Code Analysis*
Enforcement Mandatory Statewide Mandatory Statewide
Can use COM/REScheck Yes Yes


Model Code Savings Potential

Statewide Savings Potential (2010-2030) Residential Commercial
Cost $0.34B $0.14B
Energy (primary) 40MBtu 20MBtu

Consumer Cost Savings

Consumer Cost Savings Residential
per Home
per 1,000 ft2
Annual ($) $255 $100
Annual (%) 17.3%
Life-cycle (30 year) $3577 $1530
Simple Payback 4.4 years 0.0 years
Positive Cash Flow 0.6 years


Code Type: Residential Commercial
Field Study Yes No
Training Program No No

Additional Information



    Idaho Residential Energy Standards (IRES) (Senate Bill [SB] 1591) was enacted in 1990 and was the only legislated statewide energy code in Idaho. However, it was a minimum standard and local jurisdictions could adopt more efficient energy codes.

    A 1994 state-sponsored analysis of new construction by jurisdiction and energy code indicated that approximately 38% of housing starts were built to IRES. Five different energy codes listed below were used in the state as of late 1994:

      • Idaho Residential Energy Standard (IRES)
      • Northwest Energy Code (NEC), adopted by 46 jurisdictions
      • Bannock County Energy Code (BCEC), based on the NEC
      • Boise City Ada County energy code, based on the NEC
      • IDWR's fuel-blind code for non-electrically heated homes, adopted by Lewiston.

    Senate Bill 1208 was passed in March 1995 modifying the 1990 IRES to the 1996 IRES, which became effective January 1, 1996. The 1996 IRES eliminated the requirement for builder certification to the Department of Labor and Industrial Services in cities or counties that have not adopted the IRES or an alternate code.

    HB 611 took effect July 1, 2000. It required that any jurisdiction that has adopted the UBC, adopt the most current version of the code, which was the 1997 UBC. In the past, a jurisdiction adopting the UBC could elect to leave out the appendix that included the energy code.

    Dirk Kempthorne signed House Bill 586 on March 27, 2002, which required local governments that issue building permits and enforce building codes to adopt by January 1, 2003, the International Building Code as well as the International Energy Conservation Code.

    On March 23, 2004, House Bill 756 was signed into law by Govenor Dirk Kempthorne updating the Idaho Building Code Act for the adoption of the 2003 International Building, Residential, and Energy Codes. Adoption and implementation of the 2003 IECC for all Idaho building code adopters was required by no later than January 1, 2005.

    On March 26, 2007, the governor signed HB 137, which made the 2006 IECC mandatory for new buildings statewide effective January 1, 2008.

    On April 17, 2009, the governor signed H0220, adopting the 2006 editions of the IBC, IRC, and IEBC, as well as reaffirming the use of the 2006 IECC.

    The Building Code Board intends to adopt the 2009 editions of the above-identified building codes; however, the text of the rule that the Board will promulgate to adopt the Codes is unknown at this time and will be established based on any amendments made to the codes as determined through the negotiated rulemaking process. The Board can make no amendments to the International Residential Building Code which provide for standards that are more restrictive than those published by the International Code Council. Additionally, the Board must abide by the newly enacted state law (as expressed in House Bill 218a) that relates to the International Building Code and the International Residential Code provisions regarding the installation of fire sprinklers in single family homes and multiple family dwellings up to two (2) units.

    The Division of Building Safety has multiple legislative proposals.

    On March 23, 2010, the City of Nampa proposed several amendments to the planned 2009 Building Code.

    On January 1, 2011, the 2009 IECC with no amendments was adopted, and all jurisdictions were required to comply.

    State-Owned/Funded Buildings

    A building project constructed by or renovated by a state agency or for occupancy or use by a state agency that is larger than 5,000 gross ft2 of occupied or conditioned space must be 10-30% more energy efficient than similar buildings on similar sites. See Energy Efficient State Building Act, 2008.

    Adoption Process

    The Idaho Building Code Board has authority to adopt and amend building codes pursuant to I.C. Section 39-4109. Updated codes are adopted every three years by the Idaho Legislature as they are revised by the International Code Council.

    The 2006 building and energy codes were presented for adoption by the 2007 Idaho Legislature for implementation in Idaho in July 2007.

    The effective date of the 2009 IECC was January 1, 2011 (IDAPA

    Enforcement Process

    Enforcement of building and energy codes is handled by local building code adopters. Energy codes for state facilities and modular prefabricated buildings are enforced by the Idaho Division of Building Safety. Public school plans may be examined by a ICC-certified examiner instead of the Division of Building Safety (2009 HB251).

    Compliance Process

    On May 6, 2010, Idaho was announced as one of the states that will participate in BECP's Compliance Evaluation Pilot Study.