Whole of Home Assessment — NatHERS WoH Score Explained
Under NCC 2022, every new home needs two NatHERS scores: a 7-star thermal rating for the building envelope and a Whole of Home (WoH) score out of 100 covering hot water, heating, cooling, lighting and solar. Most states require WoH ≥ 60.
7-star rating vs Whole of Home — what's the difference?
| Aspect | 7-star thermal rating | Whole of Home score |
|---|---|---|
| What it measures | Building envelope (walls, roof, floor, glazing, orientation) | Fixed appliances + on-site PV |
| Scale | 0–10 stars | 0–100 score |
| NCC 2022 minimum | 7 stars | 60 (varies by state) |
| Improved by | Insulation, double glazing, shading, sealing | Heat pump HWS, reverse-cycle HVAC, solar PV, LED lighting |
| Modelled in | AccuRate / FirstRate5 / BERS Pro | Same software — WoH module |
What's included in the WoH score?
Hot water
Gas storage, gas instant, electric storage, heat pump or solar HWS. Heat pump and solar score highest.
Heating & cooling
Reverse-cycle splits, ducted systems, hydronic, gas heaters. Reverse-cycle outperforms gas every time.
Lighting
LED density (W/m²) per room. Whole-of-home LED is now standard practice for compliance.
Solar PV & battery
On-site generation and storage offset modelled energy use — the single biggest lever to lift WoH.
Pool & spa pumps
Pumps, heaters and filtration are counted if present. Variable-speed pumps score better.
What's excluded
Plug loads (fridges, TVs, computers, appliances) — only fixed, hard-wired equipment counts.
Typical WoH scores by home setup
| Setup | Hot water | Heating | Solar PV | Typical WoH |
|---|---|---|---|---|
| Gas-heated, no solar | Gas instant | Gas ducted | None | 40–55 (fails) |
| Mixed, small solar | Gas instant | Reverse-cycle | 3 kW | 60–70 |
| All-electric, mid solar | Heat pump | Reverse-cycle | 6 kW | 85–95 |
| All-electric + battery | Heat pump | Reverse-cycle | 10 kW + battery | 100+ |
Scores can exceed 100 when on-site generation more than offsets fixed appliance use — common in well-designed all-electric homes.
Fastest ways to lift WoH
- • Add 5–6 kW solar PV (+20–30 points)
- • Heat pump hot water instead of gas (+10–15)
- • Reverse-cycle instead of gas heating (+10)
- • All-LED lighting (+3–5)
- • Add battery storage (+5–10)
State-by-state minimums (2026)
- • NSW: BASIX energy score (separate from WoH)
- • VIC, QLD, SA, WA, TAS, NT: WoH ≥ 60
- • ACT: WoH ≥ 60 + EER disclosure on sale
- • Class 2 apartments use modified targets per dwelling
Need a NatHERS + Whole of Home assessment?
Every accredited NatHERS assessor produces both your thermal star rating and your WoH score on the same certificate. Get free quotes from assessors in your area.