Passive Design Principles — 8 Rules for a Comfortable, Low-Energy Home
Passive design uses the sun, wind and building fabric — not mechanical systems — to keep a home comfortable year-round. Get it right at design stage and you cut heating and cooling loads by 40–80% for close to zero extra build cost.
What is passive design?
Passive design is the practice of shaping a building — its orientation, form, glazing, mass and fabric — so it maintains comfortable indoor temperatures with minimal energy input. In Australia it underpins every high-star NatHERS rating and is the foundation of the 6-star NCC minimum and beyond.
The principles below apply to new builds and, in adapted form, to renovations. They stack: no single move gets you to a 7-star rating on its own, but combining orientation, glazing, insulation and shading routinely does.
The 8 principles
1. Orientation
Long axis east–west so living rooms face within 15° of true north. Winter sun (low angle) enters and warms; summer sun (high angle) is easy to shade with eaves.
2. Glazing & shading
Concentrate glass on the north; keep east and west glass small and externally shaded. Aim for 20–25% glass-to-floor ratio, double-glazed or low-e, U-value ≤ 3.0 W/m²K.
3. Thermal mass
In temperate and cool zones (4–7), expose concrete slab or masonry to winter sun so it stores heat and releases it overnight. In tropical zones use lightweight construction instead.
4. Insulation
Meet or beat NCC 2022 minimums: ceiling R6.0–R7.0, walls R2.5–R3.0, underfloor R2.0–R2.75. Continuous with no thermal bridges through timber studs or steel.
5. Air-tightness & ventilation
Seal gaps around windows, penetrations and wet-area exhausts to ≤ 5 ACH50, then add controlled cross-ventilation or an HRV/ERV so fresh air is deliberate — not draughty.
6. Shading & landscape
800–900 mm eaves on the north, external blinds or louvres east/west, deciduous trees for summer shade that drop leaves for winter sun.
7. Zoning & layout
Group bedrooms and bathrooms on the cool side; put living areas on the sunny side. Doors close off unused zones so heating/cooling is targeted.
8. Colour & finishes
Light-coloured roofs and walls in hot climates (solar absorptance ≤ 0.4); dark, absorbent finishes on north-facing thermal mass in cool climates.
How the principles change by climate zone
| Climate | Priority | Avoid |
|---|---|---|
| Tropical (Zones 1–2) Darwin, Cairns | Elevated floors, deep verandahs, cross-ventilation, light roofs, ceiling fans | Heavy thermal mass indoors, unshaded west glazing |
| Sub-tropical (Zone 3) Brisbane, Perth | Shading + cross-ventilation, insulated roof, north-facing living | Large west glazing, dark roof colours |
| Temperate (Zones 5–6) Sydney, Adelaide, Melb. | North-facing glass with eaves, exposed thermal mass, R6 ceiling, double glazing | Poor orientation, single glazing on south/west |
| Cool / cold (Zones 7–8) Hobart, Canberra, Alps | Air-tightness, triple glazing / low-e, R7+ ceiling, sun-trapping courtyard | Draughts, thermal bridges, oversized south glazing |
See the full Australian climate zones guide for the 8 NatHERS zones.
Printable checklist by climate zone
Tick off each item as your design meets it. Links open the deep-dive resource for that step.
Tropical (Zones 1–2)
Darwin, Cairns, Broome
Sub-tropical (Zone 3)
Brisbane, Perth, Gold Coast
Temperate (Zones 5–6)
Sydney, Adelaide, Melbourne, Perth Hills
Cool & cold (Zones 7–8)
Hobart, Canberra, Ballarat, Alpine
myenergyrating.com.au — Passive Design Checklist
Applying passive design to a renovation
You can't rotate an existing house, but you can still capture 60–70% of the benefit. Start with the fabric: underfloor and ceiling insulation, then retrofit double glazing or secondary glazing on the worst-oriented windows. Add external shading (awnings, external blinds) to east and west glass. Seal the top and bottom of the house — ceiling penetrations and floor gaps drive the biggest air leaks.
If you're extending, put the new living zone on the north side and let the old south rooms become bedrooms. That single move typically lifts an existing home from a 3-star to a 6-star NatHERS rating.
See how your design stacks up
Model your plans with the free calculator or get an accredited assessor to run the numbers before you lodge for DA.