What Does The Energy Rating Mean?
The ratings are calculated by a NatHERS (Nationwide Housing Energy Rating Scheme) computer simulation of an individual house design to estimate the thermal comfort.
The calculations are based on 69 different ‘Climate Zones” and allows comparison of different properties in the same climate zone.
The following table shows the Energy Load (heating,cooling, lighting and hot water) for various capital cities for each of the star rating band.
| 6 Star | 7 Star | 8 Star | 9 Star | 10 Star | |
| Adelaide | 27 | 19 | 13 | 6 | 1 |
| Brisbane | 12 | 10 | 7 | 5 | 3 |
| Hobart | 43 | 31 | 20 | 9 | 0 |
| Melbourne | 32 | 23 | 15 | 7 | 1 |
| Perth | 19 | 14 | 9 | 5 | 1 |
| Sydney | 11 | 8 | 6 | 4 | 2 |
The values are in kilo watt hours/m2/annum.
I haven’t shown less than 6 stars as that is the minimum for new houses.
As you can see if you go all the way to 10 stars the energy load will be virtually nil.
Example
If you are building a 200m2 house in Melbourne at the minimum 6 Star Rating your annual energy load will be:
200 x 32 = 6,400 kilo watt hours
By increasing the rating to 8 star the calculation becomes:
200 x 15 = 3,000 kilo watt hours
a significant reduction of more than 50%!