Published
Idaho has one energy code, and neither desk in St. Anthony can add to it.
One energy code, set at the state level
Energy is the one part of the building code where Idaho has decided there is a single answer for every city and county. Since July 1, 2022, the state energy code has been the 2018 International Energy Conservation Code as amended by the Idaho building code board and approved by the legislature — the model code plus the state’s own changes, together named the Idaho Energy Conservation Code. That much is subsection (1) of Idaho Code §39-9701, the lead section of Title 39’s energy chapter. Subsection (2) is where it gets sharp for anyone building under a local desk:
“The provisions of this chapter preempt, eliminate, and prohibit any cities, counties, incorporated or unincorporated areas, special use districts, or any other local governmental entities of any kind from adopting energy code or energy-related requirements through any code, ordinance, process, policy, or guidance that differ from or are more extensive than the requirements of the Idaho energy conservation code as provided for in this chapter.”
— Idaho Code §39-9701(2), Idaho Energy Conservation Code. Added 2022, chapter 302; amended 2023, chapter 236. Retrieved 11 September 2026
Three verbs in a row — preempt, eliminate, prohibit — and then a list of ways around the rule that the legislature closed one by one. Not just ordinances: any code, process, policy, or guidance. A city cannot do it in its building code, cannot do it through a permit-condition process, cannot do it in a policy memo, and cannot do it in guidance a reviewer applies at the counter. If an energy requirement differs from the state code, or reaches further than it, it is not lawful for a local government to impose it in Idaho.
What the state fixes, and what it leaves local
The preemption is total on the requirements themselves, but the statute carves out one bookkeeping exception: Chapter 1 of the 2018 IECC, the administrative chapter, stays local. That split is easiest to read as a table:
| Question about energy | Who decides, under §39-9701 |
|---|---|
| Which energy code applies anywhere in Idaho | The state — the 2018 IECC as amended by the building code board and approved by the legislature |
| The performance requirements themselves — envelope, equipment, the works | The state code. A city or county cannot add to it, raise it, or differ from it |
| Energy-related requirements sneaking in through policy or counter guidance | Preempted, same as ordinances — the statute names all four vehicles |
| Administrative process — how a city or county runs applications, review and its own paperwork (IECC Chapter 1) | Stays local. The carve-out is expressly for the administrative processes of any city, county or other local entity |
So the line is not “state good, local bad.” It is: what must be achieved is state-set; how the paperwork runs is local — and the local paperwork lane is exactly where the 2025 timely-review law also lives. If you have not met that one yet, it puts a written, ten-business-day clock on the completeness conversation at every permit desk in the state: the ten-business-day law explained.
The clause that reaches back in time
Subsection (3) answers the question every lawyer asks first: what about rules already on the books? The chapter “shall apply to codes or amendments adopted by local jurisdictions prior to, on, or after July 1, 2022.” A city energy ordinance passed in 2019 does not survive by seniority. Anything a local government in Idaho was enforcing that goes beyond the state energy code is swept into the same preempted pile as anything it might pass next year.
For a builder or owner around St. Anthony, this settles an argument before it starts:
- Inside the city limits, the city runs its own permit desk — but on energy it enforces the state’s code, not a city-strengthened version of it. There is no lawful municipal premium on insulation, windows, or equipment efficiency here.
- Outside the city, the county is under the same ceiling. Whatever side of the line your lot falls on, the energy requirements themselves do not change, because no local government in Idaho has the power to change them.
- Both desks still keep their administrative processes — the forms, the sequence, the review steps. The carve-out for Chapter 1 means a city can run its counter its own way; it just cannot raise the bar the plans are measured against.
Why this matters when you read a local checklist
Local documents do not always say where their energy lines come from — a county checklist, a city handout, a counter conversation — and the preemption decides what those documents can lawfully contain:
- Restating the state code is fine. The statute forbids differing from or reaching beyond the state code; a local document printing the state’s own numbers is describing the same code, not adding to it.
- Different desks, same ceiling. The two desks around St. Anthony print different code lists for different trades — a mismatch this site has already mapped in the two code books and what each desk prints — but on energy, both lists bottom out in the same state code.
- More than the state code is the trigger. When any document or reviewer asks for something beyond it, the question that resolves the ask is short: which provision of the Idaho Energy Conservation Code is this?
And the state code is not frozen. The board amends it by rule, the legislature approves those amendments, and the current amended version is what the desks enforce — the same board rule that sets which editions of the building codes apply, a story this site tells separately.
Use the preemption without misreading it
- Get the state energy code — the 2018 IECC as Idaho amended it — and treat it as the whole energy answer for your project.
- Read your desk’s documents as process instructions, not as a second energy code; Chapter 1 administration is the only energy lane a local government keeps.
- If a requirement looks like it exceeds the state code, ask for the provision it comes from — a state-code citation or nothing.
- Watch the calendar words: anything adopted before July 1, 2022 does not survive the preemption, and neither does anything after.
- Do not confuse this chapter’s reach with the rest of the codes — it covers energy only; the administration of everything else runs through the building code act.
- Keep the ask in writing, on the record, so the answer lands next to your permit file.
- Then call (208) 656-1745 with the one energy question your build actually turns on — which side of the line, which desk, which sheet.
Common questions
What is Idaho Code 39-9701?
The lead section of Idaho's energy code chapter. It sets the 2018 International Energy Conservation Code, as amended by the state building code board and approved by the legislature, as the Idaho Energy Conservation Code from July 1, 2022, and preempts local governments from adopting energy requirements that differ from or go beyond it.
Can the City of St. Anthony require better insulation than the state energy code?
No. Section 39-9701(2) preempts cities, counties and every other local entity from adopting energy code or energy-related requirements - through code, ordinance, process, policy, or guidance - that differ from or are more extensive than the state energy code.
Can Fremont County add its own energy rules outside the city limits?
No. The preemption applies to counties the same as cities, and to any special use district or other local governmental entity of any kind. The county enforces the state energy code on that side of the line too.
Which energy code applies in Idaho right now?
The 2018 International Energy Conservation Code as amended by the Idaho building code board through rulemaking and approved by the legislature - together named the Idaho Energy Conservation Code, in force on and after July 1, 2022.
What does the 'Chapter 1' exception cover?
Local administrative processes. The preemption does not reach chapter 1 of the 2018 IECC, so a city or county keeps control of how its own application, review and enforcement paperwork runs - just not of the energy requirements themselves.
Does the preemption apply to local energy rules adopted before 2022?
Yes. Subsection (3) makes the chapter apply to codes or amendments adopted by local jurisdictions prior to, on, or after July 1, 2022 - older local energy additions do not survive.
Does Idaho's energy preemption cover the whole building code?
No - this chapter covers energy only. How building permits are administered generally runs through the Idaho Building Code Act, where the 2025 legislature added a written ten-business-day timeline for residential permit completeness review.
If a checklist asks for more than the state energy code, what should I ask?
Ask which provision of the Idaho Energy Conservation Code the requirement comes from. Local documents may restate the state code, but a requirement that differs from it or reaches beyond it is preempted, whatever document it appears in.
Who can change the energy code in Idaho?
The Idaho building code board, through rulemaking under the Idaho Administrative Procedure Act, with the legislature's approval - the same route that produced the state's current amendments to the 2018 IECC.