Worked Estimates and Checklists
Reading the Zoned Energy Rating Label: star ratings, efficiency and noise for air conditioners and heat pumps
How to read the Zoned Energy Rating Label on reverse cycle air conditioners, what COP and seasonal efficiency mean, and how to compare heat pump water heaters without a star label.
Reverse cycle air conditioners sold in Australia carry an energy rating label regulated under the Greenhouse and Energy Minimum Standards (GEMS) Act 2012. The current design is the Zoned Energy Rating Label, which shows separate star ratings for heating and cooling in three climate zones — hot, average and cold — so you can read the rating for where you live rather than a single national figure. More stars mean more efficient in that zone. Heat pump water heaters are compared differently, using their registered performance for STCs and the manufacturer's data. This guide shows how to turn the label into a running-cost comparison. It is part of the heating and cooling quote checklist.
What the label shows
The Zoned Energy Rating Label typically includes:
| Element | What it tells you |
|---|---|
| Map of climate zones | Which zone your home falls in: hot, average or cold |
| Star ratings for cooling and heating in each zone | Relative efficiency of the model in that climate |
| Annual energy use figures (kWh) for each zone | Estimated electricity use under a standard usage assumption |
| Capacity | Rated output |
| Noise level | Sound level information for indoor and outdoor units on many labels |
The label is a comparison tool. The kWh figures assume a standard number of operating hours, which may not match your household, but they let you compare two models on the same basis.
Which zone are you in?
Broadly:
- Hot zone: northern Australia and parts of inland Queensland and WA where cooling dominates.
- Average zone: much of the east coast and southern capital cities' warmer areas.
- Cold zone: Canberra, Tasmania, alpine and highland areas and colder parts of southern states, where heating dominates.
The label's map shows the boundaries. If you are near a boundary, compare the ratings in both zones.
Efficiency terms in plain language
- COP (coefficient of performance) — heat delivered ÷ electricity used, for heating. A COP of 4 means 4 kWh of heat per 1 kWh of electricity.
- EER (energy efficiency ratio) — the cooling equivalent.
- Seasonal efficiency (SCOP/SEER-style measures) — averages across a season of varying outdoor temperatures, which is closer to real use than a single test point. The zoned label's ratings are based on seasonal performance.
Worked example: comparing two 7.1 kW models
Illustrative figures from two labels for the cold zone, heating:
| Model A | Model B | |
|---|---|---|
| Heating stars (cold zone) | More stars | Fewer stars |
| Label annual heating energy (cold zone) | 1,600 kWh | 2,000 kWh |
| Installed price (illustrative) | $4,600 | $4,100 |
Running-cost difference. At an illustrative 32 c/kWh:
- Model A: 1,600 × $0.32 = $512 a year.
- Model B: 2,000 × $0.32 = $640 a year.
- Difference: $128 a year.
Payback of the dearer model. $4,600 − $4,100 = $500 extra ÷ $128 ≈ 3.9 years.
If you use the system less than the label assumes, the payback lengthens; if more, it shortens. Scale the label's kWh by your own hours: if you heat about half the label's assumed hours, use half the kWh. All numbers are illustrative.
Comparing heat pump water heaters
There is no star rating label for heat pump water heaters comparable to the air conditioner label. Instead, compare:
| Factor | Where to find it |
|---|---|
| Registered model and STC count for your postcode | Clean Energy Regulator register; installer's STC calculation |
| Rated performance / COP at test conditions | Manufacturer's specification sheet |
| Low-temperature operating range | Manufacturer's data (important in cold climates) |
| Noise level (dB(A)) | Manufacturer's data |
| Tank warranty and compressor warranty | Warranty document |
| State eligibility | Solar Victoria, VEU or NSW eligible product lists |
A higher STC count for the same tank size in the same postcode generally reflects higher modelled energy savings, which makes it a useful proxy for efficiency when comparing models. See the STC guide and the heat pump worked example.
Noise: read the numbers
Noise causes many complaints, especially for outdoor units and heat pump water heaters running overnight.
- Decibel scales are logarithmic: an increase of about 10 dB is perceived as roughly twice as loud.
- Compare sound power with sound power, and sound pressure with sound pressure; they are measured differently.
- Placement matters as much as the rating: a unit in a narrow side passage can echo.
- Check your state environment protection rules and any council requirements on residential equipment noise, particularly at night.
Checklist for using the label
- Find your zone on the map.
- Read the heating and cooling stars for your zone.
- Note the annual kWh for your zone, and scale for your expected use.
- Multiply by your tariff for an annual cost.
- Compare the extra purchase price with the yearly saving.
- Check noise levels and placement.
Then put the capacity into the installation cost estimator and the running cost into your overall comparison in the running-cost guide.
Frequently asked questions
Do ducted systems have energy rating labels?
Larger ducted units may not carry the same consumer label as wall splits, depending on capacity and the rules for that product class. Ask for registered efficiency data, which can be checked on the Energy Rating registration database.
Is a higher star rating always worth paying for?
Not always. If you rarely use the system, a cheaper model with fewer stars may cost less over its life. Do the payback arithmetic.
Where can I check a model's registration?
Products regulated under GEMS are registered; the Energy Rating website provides a searchable registration database.
Does the label include standby power?
The label's annual energy figures are based on a standard test method. For details on what is included, see the Energy Rating website.
Official sources
- Energy Rating — Zoned Energy Rating Label and product registrations
- Federal Register of Legislation — Greenhouse and Energy Minimum Standards Act 2012
- Clean Energy Regulator — heat pump water heater register
- energy.gov.au — understanding energy ratings
