If you are replacing an existing system in an existing home, the 2026 provision does not apply to you. Full stop.
What the code actually says
The provision is Section N1105.8 of the 2026 Oregon Residential Specialty Code. Here it is, in full:
“N1105.8 Heat pump for split-system air-conditioning. In new dwellings where split-system air-conditioning is installed, the outdoor condensing unit and indoor evaporator coil shall have heat pump operation that provides both heating and cooling. Heat pump operation for heating shall be first stage heating. The heat source sized for the dwelling design-day heating load provides heating where first stage heating cannot maintain the minimum required space temperature.”
Read the first eleven words again: “In new dwellings where split-system air-conditioning is installed.” Two conditions, both of which must be true. A new dwelling. And air conditioning being installed in it.
What the state says it does NOT do
This is not our interpretation. The Building Codes Division published a technical summary specifically to clear this up, and it contains its own list headed “What Section N1105.8 does NOT do”:
From the Building Codes Division technical summary
- “Does not dictate the heating system fuel for the home.” The heating system “may remain electric resistance, natural gas, propane, biofuel, or other fuel.”
- “Does not require heat pumps for existing HVAC systems.” N1105.8 “is for new dwellings only and does not apply to the replacement (alteration) of an existing cooling system.”
- “Does not require re-sizing the air-conditioning system cooling capacity” when a heat pump is used.
- “Does not prohibit the installation of a cooling-only system” without first-stage heat pump operation — there are alternate compliance pathways.
So where does the “mandate” story come from?
Three things got blurred together.
It is real, and it is a genuine change — for new construction with air conditioning. Builders are affected. Homeowners replacing equipment are not.
It is not a gas ban. Pair a heat pump with a gas furnace and you get a hybrid, or dual-fuel, system: the heat pump handles first-stage heating and the furnace takes over below a set-point temperature. The code explicitly contemplates this.
It is conditional. No air conditioning installed, no requirement. There are also exceptions for new dwellings meeting certain prescriptive measures, and five alternate compliance pathways in the draft code — including a prescriptive option where two additional energy measures substitute for the first-stage heat pump entirely.
Timing, stated carefully
The Residential and Manufactured Structures Board approved the 2026 ORSC energy package on 18 February 2026, with an anticipated effective date of 1 October 2026 and a six-month phase-in making it mandatory around 1 April 2027.
The technical summary we have quoted describes proposed language going through the code review process. Code language can change between proposal and adoption. If a date or a detail matters to your project, ring the Building Codes Division on 503-378-4133 and confirm it rather than relying on this page or on anybody's quote.
What to do if you have been told otherwise
Ask one question: “Which code section requires that for my replacement?”
There is a decent chance the answer is honest confusion rather than a sales tactic — this has been widely misreported, and plenty of good contractors have read the headlines rather than the code. Either way, the answer determines whether you are choosing a heat pump or being sold one.
A heat pump may well still be the right buy for your house. Portland's climate suits them, and the Energy Trust incentives are real if you are replacing electric heat. But “the state requires it” should not be the reason, because for an existing home it isn't true.
Sources, last verified 23 September 2026: Oregon Building Codes Division technical summary, First-Stage Heat Pump — 2026 ORSC Provisions Summary (oregon.gov/bcd), from which the code text and the “does NOT do” list are quoted verbatim; and reporting of the Residential and Manufactured Structures Board vote of 18 February 2026. This page is general information about a code provision, not a code ruling — your building official's interpretation governs your project.