NCC 2022 is the largest single change to QLD residential energy compliance in twenty years. For QLD project home builders, it converted solar from a marketing feature into a compliance lever — and in doing so, changed the maths of how solar shows up in the cost-per-square-metre of a build.
Most builders haven't actually run that maths. This article does, comparing solar to the other three NatHERS-uplift levers (glazing, insulation, orientation) on a cost-per-NatHERS-star basis. The conclusion is straightforward: solar is the cheapest path to 7-star compliance for almost every QLD project home build, by a meaningful margin.
What changed under NCC 2022
Pre-2022, NatHERS was a thermal-only rating: how much heating and cooling energy a home would consume given its envelope, glazing, orientation, and shading. Solar didn't enter the calculation at all because solar is a supply-side intervention, not a thermal-envelope one.
Under NCC 2022, NatHERS was extended into a whole-of-home energy budget. The home's regulated equipment (hot water, heating/cooling, lighting, pool pumps) is counted on the demand side. On-site renewable generation — i.e., solar — is counted on the supply side. The net result rolls into the star rating.
That means solar PV directly contributes to NatHERS for the first time. Every kWh the panels generate is a kWh the regulated equipment doesn't have to draw from the grid, and the whole-of-home score improves accordingly.
The minimum new-build NatHERS rating in QLD under NCC 2022 is 7 stars. Standard QLD project home spec, built without solar, generally lands at 6.0–6.5 stars. The gap of 0.5–1.0 stars is the compliance problem every builder has to solve.
The four levers
There are four ways to close that 0.5–1.0 star gap. Each has a different cost profile and different design implications.
- Solar PV — supply-side intervention. Adds generation to the whole-of-home budget without changing the building envelope.
- Insulation upgrade — typically thicker ceiling batts, sometimes wall and floor batts. Adds R-value, reduces conduction load.
- Glazing upgrade — clear single-glazed → low-E single → low-E double. Reduces solar heat gain in summer, conduction loss in winter.
- Orientation / passive design — siting the home with primary glazing facing south, increasing eaves, adding shade structures. Reduces summer thermal load.
Cost-per-star analysis (typical QLD project home, climate zone 2)
Numbers below are typical for a single-storey 4-bed project home, ~200 m², built in a Brisbane / Logan / Ipswich / Moreton Bay growth corridor. They'll vary by spec; orders of magnitude are reliable.
| Lever | Typical uplift | Builder cost | Cost per star |
|---|---|---|---|
| 6.6 kW solar (no battery) | ~+1.0 stars | $3,500–$4,500 (trade) | ~$3,500–$4,500 |
| 6.6 kW solar + 9.6 kWh battery | ~+1.5 stars | $8,000–$10,000 (trade) | ~$5,300–$6,700 |
| R5.0 ceiling batts (vs R3.5 standard) | ~+0.3 stars | $1,000–$1,500 | ~$3,300–$5,000 |
| Low-E double glazing (vs clear single) | ~+0.5–1.0 stars | $4,000–$12,000 | ~$6,000–$12,000 |
| Reorientation (where possible) | ~+0.3–0.5 stars | variable; often impossible | n/a |
| Wider eaves + shade structures | ~+0.2–0.4 stars | $1,500–$4,000 | ~$5,000–$10,000 |
Solar is the cheapest single-lever path to a full star, and approximately equal-cost to the cheapest insulation upgrade — but with two structural advantages no other lever has.
The two structural advantages of solar
1. Predictable cost
Solar is a single line item with a fixed wholesale price. The other levers are variable: glazing cost depends on window area, which varies house-to-house; insulation cost depends on ceiling and wall area; orientation is sometimes impossible. Solar's cost-per-star number is the same across every home in the release.
2. Zero design impact
Solar doesn't change the slab, frame, glazing schedule, lintel details, or eave geometry. The architectural drawings stay identical. Only the roof plan needs a confirmation that the primary roof plane has clear northern exposure — which is a 10-minute check, not a redesign.
Every other lever ripples through the design. Low-E double glazing changes the lintel detail and frame thickness. Wider eaves change the roof geometry. Reorientation re-lays out the entire house. For a project home builder running 50-200 homes a year off the same plan set, that ripple is the deal-breaker.
The combined-lever play
Most QLD project homes will use solar as the primary lever (delivering ~+1.0 stars) and add a second lever to push past 7-star into the 7.5+ range, where buyers see real marketing value.
The strongest combination at the price point is 6.6 kW solar + R5.0 ceiling batts. Total uplift ~1.3 stars on a 6.0-star base, putting the home reliably at 7.3 stars. Total builder cost: ~$4,500–$5,500. No design changes.
For premium specs targeting 8 stars (display village marketing leverage), 10 kW solar + 9.6 kWh battery + R5.0 ceiling batts reliably delivers 8.0–8.5 stars. Total builder cost: ~$10,000–$12,000.
What changes under NCC 2025
NCC 2025 was published in late 2024 with state-by-state adoption from 1 May 2025 (varies by state). For QLD, the headline changes for residential are:
- NatHERS minimum may rise from 7 stars to 7.5 stars in subsequent revisions (under review at time of writing)
- Tightening of regulated-equipment standards (hot water, ducted A/C)
- Greater integration of EV-readiness and battery-readiness in the whole-of-home calculation
The structural conclusion doesn't change: solar is still the cheapest, lowest-design-impact lever. If anything, NCC 2025 makes solar more central, because the equipment-side standards being tightened mean even small generation contributions matter more.
The implication for build pricing
NCC 2022 effectively made solar mandatory for QLD project home builders, even though the regulation itself doesn't say "include solar." The maths of every other compliance lever points to solar as the rational choice. Buyers don't need to be sold on solar in 2026 — they expect it. The only question is who supplies it.
That's why builder-direct solar exists as a category, and why the structural difference between trade-only and retail-channel solar matters more than ever. When solar is mandatory, having a margin layer in solar is mandatory too — and that margin layer only survives if the supplier doesn't compete with the builder for the buyer.