NatHERS Rating — What the 0–10 Star Scale Actually Means
The Nationwide House Energy Rating Scheme gives every home a star score from 0 to 10. Here's what each star means for your bills, comfort, and NCC compliance in 2026.
The NatHERS star scale
| Stars | What it means | Energy use (vs 7★) |
|---|---|---|
| 0–2★ | Pre-1990 uninsulated home | ~5–8× more |
| 3–4★ | Older home with some insulation | ~3–4× more |
| 5★ | Pre-2010 minimum standard | ~2× more |
| 6★ | Pre-2022 minimum standard | ~40% more |
| 7★ | NCC 2022 minimum (new builds) | Baseline |
| 8★ | High-performance home | ~30% less |
| 9–10★ | Passive / near-zero conditioning | ~60–90% less |
Each star roughly halves the heating + cooling energy required. Exact MJ/m²/year benchmarks vary by climate zone.
What's modelled
- • Orientation & climate zone
- • Wall, ceiling, floor R-values
- • Window U-value & SHGC
- • Air-infiltration (draughts)
- • Shading, eaves & overhangs
- • Zoning of conditioned spaces
What's not modelled
- • Hot water system
- • Cooktop / oven type
- • Lighting & appliances
- • Solar PV generation
- • Pool / spa loads
Whole-of-home is rated separately under NCC 2022 Part 13.
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