6 Star Energy Rating — What It Means, Costs & the Path to 7 Stars
A 6 star NatHERS rating was the national minimum for new homes from 2010 to 2024. In 2026, NCC 2022 requires 7 stars + Whole of Home 60 — but understanding the 6-star baseline is still central to renovations, existing homes, and disclosure.
NatHERS star scale — what each level means
| Rating | Heating + cooling load | Typical bill impact | Compliance status |
|---|---|---|---|
| 0–3 stars | Very high | $3,000+/yr | Pre-1990 uninsulated homes |
| 4–5 stars | High | $1,800–$2,500/yr | Typical existing home |
| 6 stars | Moderate | $1,200–$1,600/yr | NCC 2010–2022 minimum |
| 7 stars | Lower — ~25% less than 6★ | $900–$1,200/yr | NCC 2022 minimum (from 2024) |
| 8 stars | Low | $600–$900/yr | Voluntary best-practice |
| 9–10 stars | Very low / net-zero ready | Near zero | Passive House territory |
From 6 stars → 7 stars: the upgrade path
Since 1 May 2024 (VIC/QLD/ACT/TAS) and 1 Oct 2024 (NSW/SA), new builds must hit 7 stars + Whole of Home 60. Here's what typically changes on the plans.
- • R2.5 wall insulation
- • R4.0 ceiling insulation
- • Standard double glazing (or Low-E single in warm zones)
- • Basic draught sealing
- • 450 mm eave overhang typical
- • R2.7–R2.8 wall insulation
- • R5.0–R6.0 ceiling insulation
- • Double glazing with Low-E coating + argon fill
- • Detailed draught sealing (weather-strips, sealed downlights)
- • Improved shading + slab edge insulation in cool zones
Typical uplift cost: $3,000–$8,000 on a new build · Payback: 6–10 years in bill savings
Where 6 stars still matters
Renovations, existing home disclosure (ACT, soon NSW/QLD), and additions where state variations still permit 6-star assessments.
Half-star increments
NatHERS reports in half-stars. A 6.5-star home sits between 6★ and 7★ — around 12% less heating/cooling load than a 6★ baseline.
Climate-adjusted
6 stars in Melbourne (Zone 21) requires different specs than 6 stars in Brisbane (Zone 10). NatHERS software adjusts to your postcode automatically.
How a 6 star rating is measured
- Plans + specs go to an accredited assessor. They enter your floor plan, orientation, wall/roof construction, glazing schedule and insulation R-values into AccuRate, FirstRate5 or BERSPro.
- Climate zone is applied. The tool loads a full year of hourly weather data for your postcode.
- Annual heating + cooling load is calculated in MJ/m² per year — the total energy needed to keep the home at 20–25 °C all year.
- Load is converted to a star rating on a 0–10 scale relative to your climate zone benchmark.
- Certificate is issued — required for building approval in most states.
Not sure what your home rates?
Get a free estimate in 60 seconds with our energy rating calculator, or connect with an accredited NatHERS assessor for the official certificate.