How much does evaporative cooling cost to run?
By Sithum Imarsha Last reviewed
About $41 in electricity plus $102 in water a summer for a 10.4 kW ducted system running 6 hours a day for 50 days, $143 together. Evaporative cooling looks free on electricity alone. It isn't.
Your result
A summer's electricity and water
$143
$41 electricity + $102 water.
- Electricity
- $41
- Water
- $102
- Fan motor power used
- 0.43kW
For comparison: a 7.1 kW split reverse-cycle costs about $190 a year to cool on its energy label, for the same state and electricity rate. That is our air conditioner calculator at its own defaults, not the hours and days above, so treat it as a rough guide.
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How we calculated this
Work out the electricity
Fan motor kW × hours a day × days a season, at your electricity rate. The motor is the only part that uses much power.
129 kWh, $41
Work out the water
Litres an hour × the same hours and days, at your state's water price. Evaporative cooling looks free on electricity alone. It isn't.
33,000 litres, $102
Add them together
$143 a season
| Size | Cooling capacity | Motor power | Checked |
|---|---|---|---|
| Small (about 10 kW cooling) | 10.4 kW | 430 W | Dated third-party source |
| Large (about 14 kW cooling) | 14.1 kW | 950 W | Dated third-party source |
Both presets are fixed-speed units. Newer inverter (variable-speed) models use noticeably less power, and likely less water, so if you have one, your real cost is probably lower than shown.
Type an exact size under Advanced and we estimate its motor power from the two presets. Between them, we draw a straight line from one to the other. Below the small one or above the large one, we scale by the nearest preset's watts per kW of cooling. Any size that is not exactly a preset is labelled an estimate.
Water use, 110 L/h (Estimate), is two costs added together. Most of it is evaporation, the water the pads give off to cool the air. A smaller part is bleed, water let out on purpose to stop minerals building up on the pads. The figure comes from one utility (Water Corporation, WA) and does not change with system size in any source we found. A larger unit almost certainly uses more water, but no source says how much more.
Climate matters more than any other factor. Evaporative cooling works by adding moisture to dry air, so it works well in dry inland areas and poorly in humid coastal ones. It also needs a window or door open, unlike a sealed reverse-cycle system. That is a real trade-off, not just a cost one.
Some areas restrict water use for evaporative cooling during drought. Check with your local water utility.
The reverse-cycle figure comes from our air conditioner running cost calculator at its own defaults, in the state you pick. It uses that tool's size and its energy label's cooling hours, not the hours and days you type here, so it is a rough guide, not a like-for-like figure.
Sources
- Water Corporation: improve the water efficiency of your evaporative air con
- Lawson Air: Braemar Evolution Series 10.4kW LPQI350
- The Air Store: Braemar Evaporative Air Conditioner LCQ350
- The Air Store: Braemar Evaporative Air Conditioner LCQ550
- SolarQuotes: evaporative cooling vs reverse cycle air conditioning (15 Dec 2025)
- CHOICE: evaporative coolers vs air conditioners
- Canstar: electricity cost per kWh
- EnergyPlans: solar feed-in tariffs July 2026
- OTTER: Tasmanian feed-in tariffs
- WA legislation: Synergy A1 tariff, charges amendment by-laws 2026 (SL 2026/140)
- Sydney Water: residential pricing 2026-27
- Yarra Valley Water: fees, charges and pricing
- Urban Utilities: 2025-26 pricing guide
- SA Water: residential water prices
- Water Corporation: understanding your water use charges
- Economic Regulator (TAS): TasWater residential customer fact sheet 2026-27
- Icon Water: 2026-27 prices (Inside Water, Jun 2026)
- Energy Rating registry: labelled air conditioners (data.gov.au, 17 Sep 2026)
- GEMS Regulator: Zoned Energy Rating Label factsheet (read via the Wayback Machine)
- GEMS Regulator: the new zoned label, for installers (read via the Wayback Machine)
- GEMS Regulator: questions and answers on the zoned label (read via the Wayback Machine)
- Energy Rating: understand the Zoned Energy Rating Label (read via the Wayback Machine)
- energy.gov.au: heating and cooling (read via the Wayback Machine)
- YourHome: heating and cooling (read via the Wayback Machine)
- energy.gov.au: summer energy savings (read via the Wayback Machine)
Questions
Is evaporative cooling really that cheap?
Not once you count water. Our example comes to about $41 in electricity plus $102 in water a season, $143 together. Electricity alone looks cheap. Water is the part people forget.
Does it work everywhere in Australia?
It works best in dry, inland climates. In humid coastal areas, evaporative cooling performs poorly because the air is already holding a lot of moisture.
Do I need to leave a window open?
Yes. Unlike a sealed refrigerative system, evaporative cooling needs somewhere for the humid air to escape, usually a window or door left ajar. That is a security, dust and noise trade-off, not a cost one.
What about pad replacement and maintenance?
Not included in this calculator's total. SolarQuotes puts pad replacement and mineral-scale maintenance at about $250 to $350 a year, for either an evaporative or a refrigerative system.
How much water does evaporative cooling really use?
About 33,000 litres a season in our example. Most is evaporation, which does the cooling. A smaller "bleed" amount stops minerals building up on the pads. The 110 L/h we use is the weakest figure in this calculator (Estimate): it comes from a single utility (Western Australia) and does not vary by system size in any source we found.