The stars on an air conditioner tell you how efficiently that unit turns electricity into cooling or heating, compared with other units of a similar size and features. They do not tell you what it will cost you to run. The figure that does that sits just to the right of the stars, in kilowatt hours, and it is the one most people walk straight past in the showroom.
Key takeaways
- The Zoned Energy Rating Label rates cooling and heating separately, across three climate zones, so you read one column and ignore the other two.
- Stars only compare like with like. A 5 star 8 kW unit and a 5 star 2.5 kW unit are not the same running cost.
- The kilowatt hour figure multiplied by your electricity tariff is the number that lands on your bill.
What You Are Actually Looking At
The label on the front of a split system in a shop is the Zoned Energy Rating Label, regulated by the Greenhouse and Energy Minimum Standards (GEMS) Regulator. It carries four pieces of information, and they do different jobs:
- Output capacity: what the unit can deliver in kW, printed across the top, with heating shown at two outdoor temperatures and cooling at one. The regulator notes these are manufacturer declared figures, tested under the Australian and New Zealand Standard conditions.
- Star rating: 1 to 10 stars, taking up most of the label, with cooling and heating rated separately.
- Estimated annual energy use: in kilowatt hours, sitting to the right of the stars. Cooling is the blue number on top, heating is the red number underneath.
- Noise: the house icon in the bottom left corner, in dB(A) at full power. A split system carries separate indoor and outdoor figures.
That outdoor noise figure is worth a second look if the condenser is going anywhere near a bedroom window or a shared fence. If it is going close to a boundary, that is worth raising with the installer before the unit is sited.
Why There Are Three Sets of Numbers
Air conditioners do not perform the same everywhere, so the label gives a seasonal efficiency rating for three climate zones across Australia and New Zealand: hot, average and cold. The Energy Rating scheme builds each zone from a reference location. Hot uses Rockhampton, average uses Richmond, north west of Sydney, and cold uses Canberra.
Read your own zone and ignore the rest. If you are in Brisbane, the cold zone heating stars are not describing your winter. The Energy Rating Calculator on energyrating.gov.au will tell you which zone your postcode falls into.
The Trap With Star Ratings
Here is where people get caught. Stars are a comparison within a size bracket, not an absolute score. The regulator is blunt about it: star ratings of models with different capacities or features cannot be compared. Two units can both wear 5 stars, and the bigger one will still cost more to run, because it is doing more work.
So the order matters. Work out the capacity the room genuinely needs first, then use the stars to separate models that are already the right size. Chasing the biggest star count on the wall is how people end up with an oversized unit that short cycles. If you have not settled on a capacity yet, start with working out how many kW you actually need and come back to the label after.
Turning Kilowatt Hours Into Dollars
The regulator gives the arithmetic straight out: annual running cost equals total energy use for cooling and heating in kWh, multiplied by your electricity tariff in dollars per kWh. Your tariff is on your bill.
Their own worked example is a reverse cycle non ducted single split rated at 8.5 kW cooling and 10 kW heating, sitting in the hot zone, with 6.5 stars for cooling and 3 stars for heating. Estimated use is 2,254 kWh a year, made up of 2,047 kWh cooling and 207 kWh heating. At a tariff of $0.4659 per kWh that comes to $1,050.14 for the year, being $953.70 cooling and $96.44 heating.
Notice what that split tells you. In a hot zone the heating stars barely touch the bill, because the thing hardly heats. In Canberra that balance flips. The stars worth caring about are the ones attached to the season you actually use. Our guide to air conditioning running costs goes further into where the money goes across a full year.
Where the Label Stops and the Switchboard Starts
Once you step up to a physically bigger, higher kW system, the constraint often stops being the label and becomes the electrical supply behind it. A hard wired unit wants its own circuit, and the switchboard has to have the room and the capacity to give it one. On older homes still running a small board with few spare ways, that can decide which model you can have. Worth getting a sparkie like Hack-It Electrical Solutions to look at the board before you commit, not after the unit is sitting in the driveway.
What the Label Will Not Tell You
The label is genuinely useful, but it has edges. Three worth knowing:
- It is not on everything: in stores the label is mandatory on single phase, non ducted, unitary or single split air conditioners up to 30 kW. Ducted systems are a different conversation.
- Online is not covered: retailers selling online are not required to display it, so if a listing has no efficiency information, ring or email and ask.
- The numbers assume a usage pattern: the annual kWh figures are built on set run hours per zone, drawn from NatHERS climate files. The hot zone assumes 2,247 cooling hours and 277 heating hours a year, the average zone 840 and 1,921, the cold zone 545 and 2,660. Run yours harder than that and your bill will be higher, no matter what the label says.
None of that makes the label unreliable. It is a comparison tool built on a standard assumption, not a prediction of your household. The regulator’s own page on understanding the Zoned Energy Rating Label breaks down every element on it.
