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Phase 2 · Design and engineering · Step 2.5

Verify ORSC energy compliance for the alteration

The Oregon Residential Specialty Code's energy chapter applies to additions and alterations. An energy consultant or your designer runs the compliance path, sizes equipment, and produces the documentation PP&D wants in the submittal.

Who
Energy consultant, Designer
How long
2-4 weeks
Cost
$1,000-$3,500
You end up with
ORSC energy compliance documentation (REScheck or prescriptive path)

What the code requires for additions

The ORSC energy chapter applies to:

  • The new addition — must meet current ORSC energy requirements for envelope, equipment, lighting, and sealing.
  • Existing portions of the house being substantially altered — at thresholds in the code, alterations trigger compliance for the altered portion (e.g., re-roofing triggers attic insulation upgrade; window replacement triggers U-factor minimums on new units).

For a second-story addition, the new envelope (walls, roof, floors over unconditioned space, windows) must meet the prescriptive U-factor and R-value table — or you take the performance path and demonstrate equivalent overall efficiency.

Compliance paths

Two main paths:

  • Prescriptive path. Each component (wall, roof, window, floor) meets the table value in ORSC. Simplest. Documented with a one-page summary on the architectural drawings.
  • REScheck performance path. Trade-offs allowed across components. Use REScheck, the DOE compliance tool, to model the project and produce a compliance report. Useful when one component (a big window wall) is below code but is offset by a high-R wall or roof.

For most additions, the prescriptive path is fine. Use performance path only when prescriptive forces a design compromise.

Equipment sizing

The energy consultant or designer also produces a Manual J load calculation for new HVAC equipment (or modified existing). This is what the mechanical sub-permit references when sizing the furnace or heat pump for the expanded house.

Mechanical ventilation

ORSC requires whole-house mechanical ventilation in additions that materially tighten the envelope. A continuous bath fan, an HRV, or an ERV — sized to the calculated airflow per ORSC. The vent design is part of the energy compliance package.

Documentation in the permit set

The final compliance documentation is one or two sheets in the permit set:

  • Energy compliance summary — path used, key values (U-factors, R-values), equipment efficiencies.
  • REScheck report (if performance path) attached as a separate PDF.
  • Manual J calc (if equipment sizing is part of scope) attached as a separate PDF.

Reach Code note

Oregon adopted a voluntary Reach Code as a more-stringent optional path. Some projects use it for tax credits or rebates; most additions don't. Confirm with your designer whether any local incentive (Energy Trust of Oregon) is worth the design overhead for your project.

Where this information came from

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