BC Energy Step Code 3
Key takeaway: Step 3 is the current provincial minimum across most of BC. Airtightness target: 2.5 ACH50. Typical wall assembly: R-22 cavity plus R-7.5 exterior. Window U-value 1.4 W/m²K. Cost premium: 1 to 3%. FortisBC rebates of $2,000 to $5,000 partially offset.
What Step 3 actually requires
Step 3 is the energy performance level that most BC municipalities have been mandating for new Part 9 residential builds since 2022 to 2024. It sits two steps above the original BC Building Code baseline and one step below the 2027 expected provincial minimum at Step 4.
Three numbers define Step 3 compliance:
| Metric | Target | How verified |
|---|---|---|
| Airtightness | ≤ 2.5 ACH@50Pa | Blower door test |
| Mechanical Energy Use Intensity (MEUI) | ≤ 50 kWh/m²/yr | HOT2000 model |
| Thermal Energy Demand Intensity (TEDI) | ≤ 30 kWh/m²/yr | HOT2000 model |
TEDI is the heating-only version of MEUI, which forces builders to focus on the building envelope rather than just adding more efficient mechanicals. You can’t paper over a leaky envelope with a better heat pump.
Typical Step 3 wall assembly
For Climate Zone 5 (most of the BC Interior including Kelowna, Vernon, Penticton, Kamloops):
| Layer (inside to outside) | Spec |
|---|---|
| Drywall | 12.7 mm (1/2”) |
| Vapor retarder | Class III (latex paint) or Class II (poly) |
| Stud cavity | R-22 batt or blown |
| Sheathing | OSB or plywood, taped seams as air barrier |
| Air/water barrier | Self-adhered membrane or fluid-applied |
| Exterior insulation | R-7.5 (typically 1.5” XPS or 2” semi-rigid mineral wool) |
| Rain screen | 19 mm furring strips |
| Cladding | Per design |
In Climate Zone 4 (Lower Mainland) you can often pass with R-22 cavity alone, no exterior insulation. In Climate Zone 6 (Whistler, Northern BC) Step 3 typically needs R-22 cavity plus R-15 exterior. See the wall assemblies guide for assembly-by-assembly details.
Windows that pass Step 3
The practical floor for Step 3 in CZ5:
- U-value: 1.4 W/m²K or better (most double-pane low-E with argon fill)
- Solar Heat Gain Coefficient (SHGC): 0.30 to 0.40 typical
- Frame: Fiberglass or vinyl with thermal breaks; aluminum without thermal breaks rarely passes
In CZ4, U-value 1.6 is workable. In CZ6, U-value 1.2 or triple-pane (U-1.0) becomes practical.
Mechanical that fits the envelope
Step 3 doesn’t prescribe specific mechanical equipment, but the energy model favors:
- Heat pump (air-source) with backup electric or gas. Most efficient path
- High-efficiency natural gas furnace (95% AFUE+). Works in CZ4/CZ5 with FortisBC connection
- HRV with 70%+ sensible recovery. Increasingly standard, not optional
- Heat pump water heater. Easy energy model points
See HVAC for Step Code for sizing approaches.
Common Step 3 failure modes
After three to four years of Step 3 across the Okanagan and Lower Mainland, the recurring blower-door fail patterns are well documented:
- Rim joist transitions. Spray foam stops short, gaps open at corners. Roughly 30 to 40% of mid-construction failures trace back here
- Window rough openings. Backer rod missing, sealant skipped on the warm side. Easy fix, often missed
- Service penetrations after drywall. Plumbers and electricians cut through the air barrier and don’t reseal
- Attic hatch. No gasket, no insulation, standard fail point
- Garage-to-house wall. Often gets framing-grade attention rather than air-barrier-grade attention
- Recessed lighting. Non-IC-rated cans in insulated ceilings create both air leaks and code issues
- Bathroom fan housings. Penetrating the ceiling air barrier without sealing the housing flange
Most of these are caught by a pre-drywall blower door test, which costs $200 to $500 and can save thousands in late-stage rework. See the air sealing checklist for the full sequence.
Cost premium: what Step 3 actually costs
For a typical 2,500 sq ft single-family home in CZ5:
| Item | Incremental cost |
|---|---|
| Energy advisor fees (model + reports) | $1,500 to $3,000 |
| Blower door test (final, sometimes mid) | $400 to $800 |
| Improved windows (U-1.4 vs builder default) | $2,000 to $5,000 |
| Air sealing materials and labour | $1,500 to $4,000 |
| Exterior insulation (R-7.5 added) | $5,000 to $10,000 |
| HRV installation (if not previously included) | $2,500 to $4,500 |
| Total incremental cost | $13,000 to $27,300 |
That’s 1% to 3% on a $1M build, more like 2% to 5% on a starter home where the fixed costs (energy advisor, blower door) don’t scale down. See cost of compliance for the full breakdown.
Rebates that offset Step 3 costs
Step 3 sits at the provincial minimum, so it isn’t directly rebated by FortisBC’s New Home Program. The available rebates kick in when you exceed Step 3:
| Source | Step 4 amount | Step 5 amount |
|---|---|---|
| FortisBC New Home Program | $9,000 to $15,000 | $11,000 to $20,000 |
| CleanBC Better Homes (heat pump) | $4,000 to $10,000 | $4,000 to $10,000 |
| Greener Homes Loan | up to $40,000 | up to $40,000 |
If you’re going to build above code anyway, building to Step 4 captures the meaningful rebate stack. See the Step Code rebates guide.
Looking ahead to Step 4
Step 4 is expected provincially in January 2027. The airtightness target drops to 1.5 ACH50, a 40% improvement. Builders developing good air sealing practices at Step 3 today will have a smoother transition. Most builders targeting 1.5 ACH50 reliably are using aerosol air sealing rather than relying on manual sealing alone.
Next steps
- Run the rebate calculator for your project numbers
- Use the Step Code checklist on your next build
- Compare air sealing methods before scoping your Step 4 transition