To get a cost-efficient 7 star energy rating, you need to build your house in accordance with the NCC Reference Building as much as possible.
Note that the following design criteria are not requirements for the NatHERS 7 star energy rating compliance. The closer your building design is to the following, the easier to get the required rating.
The characteristics of NCC Reference building are:
- Floor type: Concrete slab on ground
- Ceiling type: Flat
- Ceiling height: 2.4m
- Roof: Pitched roof with not more than 23 degrees
- Roof colour: Solar absorptance of no more than 0.6
- Roof lights: No roof lights
- Window type: Double-glazed windows
- Window area: Not more than 10% of the floor area of the room served.
- Window orientation: Increase north-facing windows, avoid east and west facing windows
- Shading: Large projection for east and west facing windows
- Wall type: Brick veneer
- Wall colour: Solar absorptance of no more than 0.6
- Internal walls: Insulate walls adjacent to unconditioned spaces
- Ceiling penetration: Avoid large penetration areas to the ceiling insulation
- Air movement: Have cross ventilation openings and ceiling fans