The ten levers to pull before you sign - so your new home hits 7-star NatHERS without runaway costs and runs near-zero net energy when you live in it.
Last reviewed by BuildPilot ·
The ten levers to pull before you sign - so your new home hits 7-star NatHERS without runaway costs and runs near-zero net energy when you live in it.
NCC 2025 mandates 7-star NatHERS for all new SA homes (up from 6 stars). 8-star is the new "high-performance" benchmark; 9-star plus solar is approaching net-zero. Get your NatHERS rating modelled at concept design - retrofitting energy performance after framing is up costs 5-10x more.
In Adelaide (Southern Hemisphere), north-facing living areas are the single biggest passive solar lever. East-facing bedrooms catch morning sun. West and south-west walls need shade in summer and good insulation in winter. If your block locks in a south-facing living wall, NatHERS performance becomes much more expensive to hit.
For an Adelaide latitude (~35° south), a 600-900mm eave on north-facing windows blocks summer sun while letting winter sun in. East and west windows need vertical shading (battens, awnings, deciduous trees). Sliding glass doors without shading on the west are the #1 cause of summer overheating we see.
Standard single-glazed aluminium frames lose heat 5-7x faster than double-glazed with thermal break. For NatHERS 7-star: spec double-glazed Low-E on north/east, double-glazed argon on south/west. Budget $8-15k extra over single glazed on a typical 4-bed home - but offset by 20-40% smaller heating/cooling bills.
R-6.0 ceiling, R-2.7 walls, R-3.5 floor (slab edge) is the new SA benchmark for 7-star. The slab edge insulation is the most-skipped item - it adds $3-5k but saves $400-600/year in heating. Demand a thermal break in cavity brick walls; without it, masonry walls perform worse than timber-frame.
Heat-pump hot water systems use 60-70% less energy than electric and 30% less than gas - and they qualify for STC rebates that cut the upfront cost by $1,000-$2,000. Pair with 6.6kW+ solar PV (typical Adelaide payback now 3-5 years) and your home runs near-zero net energy.
Passive cooling = openable windows on opposing walls. In Adelaide summer, north-east breezes after 3pm cool a house down at no energy cost - but only if there's a path through. Open-plan living with no opposing-wall windows traps heat. Design cross-ventilation at floor-plan stage.
A "7-star NatHERS" home rated for low operational carbon can still have massive embodied carbon if it's built from imported concrete and steel. Lower-carbon swaps: cross-laminated timber for upper-floor framing, low-carbon concrete (typically GP cement with 30%+ fly ash blend), recycled steel for structural elements. Budget impact: usually neutral once specified at design.
For 8-star+ targets or Passive House standard, a building physics consultant ($2,500-$5,000) runs thermal-bridge analysis, ventilation modelling and Passive House Planning Package (PHPP) calculations. Money-saving versus discovering after handover that your "high-performance" home runs 30°C inside in February.
Most SA volume builders deliver code-minimum NatHERS - that's 7-star from 2025, no upside. Ask any builder for: their 5 most recent NatHERS certificates, their air-tightness test results, and their default insulation specifications. If they can't produce these documents, they aren't actually building to high performance.
We'll email you the full 10-step framework, formatted for printing and ready to take into your next site visit or quote meeting.
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