Same size, different bill: what the energy star rating is worth in dollars

What the stars measure, and what they leave out

The star label on an air conditioner is two ratings, not one: a row of stars for cooling and a row for heating, each measured in a standard test and reported for three Australian climate zones.

Sydney sits in the average zone, and the number that matters on that label is not the stars but the annual energy figure beneath them, in kilowatt hours, because that is what your bill is made of.

Stars only turn into dollars when you multiply that figure by what you pay for power. We use the Sydney median usage rate including GST, 31.79 cents per kWh across 170 Ausgrid plans (30.65 cents across 162 Endeavour plans west of Parramatta), from the September 2026 plan data, and the official GEMS registration figures for every model we install.

That is how every model page on this site shows its running cost, and it is what the numbers below are built from. The running costs guide explains the method; this post is about the spread.

At 2.5 kW: $128 to $201 a year

A bedroom-size split is where the high star ratings live. Of the 27 models we list at 2.5 or 2.6 kW with a rating, the two ends and the middle:

The bottom of the field is a floor console, Mitsubishi Electric's MFZ-KW: 3.5 cooling stars and 2.5 for heating. Its 430 kWh of winter energy is the most at this size and takes it to 631 kWh a year, about $201. Same size, $73 apart on the bill.

Between those two sits the bulk of the range at 4 cooling stars and 3 heating stars (Panasonic's Z Series, MHI's Avanti). So at this size a step from 4 stars to 6.5 is worth about $42 a year, $420 over ten years.

Real money, but small next to what a wrong size or a bad installation costs, which is why at bedroom size we would weigh noise and the heating row before the cooling stars.

At 7 kW: $464 to $594 a year

At living-room size the stars shrink and the dollars grow. No 7 kW model in our range carries more than 4 cooling stars, where 2.5 kW goes up to 7 stars, so never compare stars across sizes; the label is only useful against other units of the same capacity.

Among the 32 rated models between 7 and 7.2 kW the spread is 1,461 to 1,870 kWh a year, $464 to $594.

On wall splits the two ends are the Daikin Alira X and the Daikin Skywall: $130 a year for the same capacity in the same house, or $1,300 over a ten-year life, and the Endeavour rate moves it by six dollars.

Panasonic's Z Series, Fujitsu's Lifestyle and Mitsubishi Electric's MSZ-AP, $497 to $524, is the range most quotes will sit in.

Ducted units at 7 kW run from Carrier's QSM to Rinnai's D Series, and the reason is the heating row again: the Rinnai is 2 heating stars against the Carrier's 2.5.

The gap grows with size

The bigger the system, the more a star is worth, because a star marks an efficiency step, and the same step applied to a bigger unit's energy is a bigger number.

At 14 kW, a common size for a family home, the ducted cost guide walks through those 13 models. At 20 kW the gap is $627 every year the unit is in the roof.

Put another way: on a bedroom split the star rating is a tiebreaker, on a whole-house ducted system it is a large number in the decision, and the only one that keeps repeating.

What most labels actually say

Across the 275 models we list with a cooling rating:

• 172 sit between 2.5 and 3.5 stars
• 39 are at 2 stars or below
• 16 reach 5 stars or more, and every one of those is a small split

A 5-star ducted system does not exist in our range, and a 3.5-star 7 kW split is near the top of its class, not the middle. The star rating is graded on a curve you cannot see from one label.

The heating row is where the field really separates.

Models that look alike on cooling stars are often half a star to a full star apart on heating, and in the Sydney-zone test figures the heating energy is larger than the cooling energy for every model at both sizes above.

So the winter row often decides the annual total, as it did for the MFZ-KW at 2.5 kW and the Rinnai at 7 kW.

How to use this when you choose

Get the size right first with the calculator: an oversized unit at any star rating costs more than a well-sized one at a lower rating, and the sizing guide explains why. Then compare only within that size, reading both rows of stars and the kWh figure under them.

Every model page here shows the annual cost at the current Sydney rate with the source and date beside it, and the compare tool puts models side by side. When two units are close on the label, the difference is usually under $30 a year, and quiet operation, the brand's local support and the warranty are the better tiebreakers.

When they are two stars apart at 7 kW or above, the dearer one to buy is often the cheaper one to own, and a fixed-price quote on both is the way to find out.

Sources

• GEMS registered air conditioners dataset (E3 program), data.gov.au, CC BY 3.0: the star ratings and annual kWh per model, synced 1 September 2026
• Energy Rating, energyrating.gov.au: how the zoned energy rating label is tested and read
• Energy Made Easy, the AER's plan data: the median usage rate across 170 Ausgrid and 162 Endeavour plans, September 2026, with GST added
• Our model pages under systems: each model's annual cost computed from the same two sources, with the date