Energy efficiency across climate zones
How to achieve higher thermal performance and energy BASIX standards in different NSW climate zones.
NSW has a varied climate, which means that houses around the state will have different energy requirements. The climate zones are outlined by the Nationwide House Energy Rating Scheme (NatHERS) and the National Construction Code (NCC).
With higher BASIX standards coming into effect from 1 October 2023, upgrades will need to be made to meet the standards. The upgrades will differ across climate zones.
In this case study we’ll examine approaches to achieve the higher standards using a typical house designed for western Sydney. Then, we’ll show modifications that would need to be made to this house in all NSW climate zones.
Example house
The example house is designed to be built on a standard rectangular shaped flat block (356m2) in suburban south-west Sydney. It’s a typical single level house with external walls made of brick-veneer, internal wall structures of timber lined with plasterboard and a waffle pod slab on ground.
The house has an internal area of 163m2 (excluding the garage) and has 4 bedrooms, 2 bathrooms and 2 garage spaces.
Orientations:
- Front of house: south-west facing
- Rear of house: north-east facing
- Living/kitchen: north-west facing
- Bedrooms: north, north-east and south facing
Sustainability features
Strategies to ensure this property achieves the NatHERS 7-star rating include:
- fitting R2.0 external wall insulation, including internal garage wall but excluding external garage wall
- fitting R4.0 ceiling insulation
- adding roof sarking with reflective side down
- installing Low E single glazed windows with aluminium frame on all habitable room windows.
Internal wall insulation was not required.
Application in all NSW climate zones
The same house was modified to achieve NatHERS 7-star in all NSW climate zones (except climate zones 9, 10 and 11) by changing external wall insulation, ceiling insulation and window properties. The required wall, roof/ceiling, floor and glazing specifications are listed in the table below.
Specifications for each home may vary from what is shown due to site differences (such as lot orientation, dimensions and overshadowing) and other design choices (such as floor area, glazing/floor area ratio, window location and size and shading devices).
Upfront costs to achieve the higher standards will maximise residents’ enjoyment of their homes year round. Homeowners and tenants should be able to rely less on heating and cooling and see reduced energy bills.
The BASIX thermal performance standards for NatHERS climate zones 9, 10 and 11 are not changing, and hence the designs shown below for these zones are to meet the current BASIX thermal performance standards (and not NatHERS 7-star).
| NatHERS climate zone | NCC climate zone | Wall specification | Roof/ceiling specification | Floor specification | Glazing specification | Ceiling fans |
| 8 (Moree) | 4 |
|
|
Waffle pod slab | Single glazing | Ceiling fans in living room |
| 8 (Moree) | 4 |
|
|
|
High performance glazing: aluminium, double glazed (U-value: <=2.5, SHGC: 0.49 - 0.60) | Ceiling fans in living room |
| 9 (Lismore) | 2 |
|
|
Conventional slab | Single glazing | - |
| 9 (Lismore) | 2 |
|
|
|
Single glazing | - |
| 10 (Byron) | 2 |
|
|
Conventional slab | Single glazing | - |
| 10 (Byron) | 2 |
|
|
|
Single glazing | - |
| 11 (Coffs Harbour) | 2 |
|
|
Conventional slab | Single glazing | - |
| 11 (Coffs Harbour) | 2 |
|
|
|
Single glazing | Ceiling fans in living room |
| 14 (Armidale) | 7 |
|
|
Waffle pod slab | High performance glazing: aluminium, double glazed (U-value: <=2.5, SHGC: >0.49) | - |
| 14 (Armidale) | 7 |
|
|
|
|
- |
| 15 (Newcastle) | 5 |
|
|
Waffle pod slab | Single glazing | Ceiling fans in living room |
| 15 (Newcastle) | 5 |
|
|
|
High performance glazing: aluminium, double glazed (U-value: <=2.5, SHGC: 0.49 - 0.60) | Ceiling fans in living room |
| 17 (Sydney CBD) | 5 |
|
|
Waffle pod slab | Single glazing | Ceiling fans in living room |
| 17 (Sydney CBD) | 5 |
|
|
|
High performance glazing: aluminium, double glazed (U-value: <=2.5, SHGC: 0.49 - 0.60) | Ceiling fans in living room |
| 18 (Nowra) | 6 |
|
|
Waffle pod slab |
|
Ceiling fans in living room |
| 18 (Nowra) | 6 |
|
|
|
High performance glazing: aluminium, double glazed (U-value: <=2.5, SHGC: >0.49) | Ceiling fans in living room |
| 20 (Wagga Wagga) | 4 |
|
|
Waffle pod slab |
|
Ceiling fans in living room |
| 20 (Wagga Wagga) | 4 |
|
|
|
High performance glazing: aluminium, double glazed (U-value: <=2.5, SHGC: >0.49) | Ceiling fans in living room |
| 24 (Yass) | 7 |
|
|
Waffle pod slab | High performance glazing: aluminium, double glazed (U-value: <=2.5, SHGC: >0.49) | - |
| 24 (Yass) | 7 |
|
|
|
|
- |
| 25 (Cabramurra) | 8 |
|
|
Waffle pod slab | High performance glazing: aluminium, double glazed (U-value: <=2.5, SHGC: >0.49) | - |
| 25 (Cabramurra) | 8 |
|
|
|
|
- |
| 27 (Mildura) | 4 |
|
|
Waffle pod slab |
|
Ceiling fans in living room |
| 27 (Mildura) | 4 |
|
|
|
High performance glazing: aluminium, double glazed (U-value: <=2.5, SHGC: 0.49 - 0.60) | Ceiling fans in living room |
| 28 (Western Sydney) | 5 |
|
|
Waffle pod slab | Single glazing | Ceiling fans in living room |
| 28 (Western Sydney) | 5 |
|
|
|
High performance glazing: aluminium, double glazed (U-value: <=2.5, SHGC: 0.49 - 0.60) | Ceiling fans in living room |
| 46 (Cobar) | 4 |
|
|
Waffle pod slab |
|
Ceiling fans in living room |
| 46 (Cobar) | 4 |
|
|
|
High performance glazing: aluminium, double glazed (U-value: <=2.5, SHGC: 0.49 - 0.60) | Ceiling fans in living room |
| 48 (Dubbo) | 4 |
|
|
Waffle pod slab |
|
Ceiling fans in living room |
| 48 (Dubbo) | 4 |
|
|
|
High performance glazing: aluminium, double glazed (U-value: <=2.5, SHGC: >0.49)) | Ceiling fans in living room |
| 56 (Eastern Sydney) | 5 |
|
|
Waffle pod slab | Single glazing | Ceiling fans in living room |
| 56 (Eastern Sydney) | 5 |
|
|
|
High performance glazing: aluminium, double glazed (U-value: <=2.5, SHGC: 0.49 - 0.60) | Ceiling fans in living room |
| 65 (Orange) | 7 |
|
|
Waffle pod slab | High performance glazing: aluminium, double glazed (U-value: <=2.5, SHGC: >0.49) | - |
| 65 (Orange) | 7 |
|
|
|
|
- |
| 69 (Thredbo) | 8 |
|
|
Waffle pod slab | High performance glazing: aluminium, double glazed (U-value: <=2.5, SHGC: >0.49) | - |
| 69 (Thredbo) | 8 |
|
|
|
|
- |
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