Installing Perth Evaporative Air Conditioning is only half the equation. What you actually want to know is what it costs to keep running once summer sets in. That’s where evaporative cooling running cost calculations get useful, because the difference between a rough guess and a real number can shape how often you’re comfortable using the system.
This guide walks through evaporative cooling cost per hour, what it adds up to across a full day, and what a typical Perth summer looks like on your power bill. We’ve based the figures below on a mid-size ducted Perth Evaporative Air Conditioning system and a standard Perth electricity rate, so treat them as a realistic working estimate rather than an exact figure for your household.
How Much Does Evaporative Cooling Cost Per Hour?
For a typical mid-size ducted evaporative cooling system running on a moderate fan speed, expect somewhere around $0.20 to $0.45 per hour, based on a Perth electricity rate of roughly $0.30 per kWh.
Smaller single-outlet units sit toward the lower end of that range. Larger ducted systems covering more of the home, or units running on high fan speed, sit toward the top. It’s a modest cost compared with refrigerated systems, which is one of the main reasons evaporative cooling stays popular across Perth.
How Much Electricity Does It Use?
Most residential evaporative cooling units draw somewhere between 750 watts and 2,000 watts, depending on the size of the fan motor, the water pump, and how many outlets the system is feeding. That works out to roughly 0.75 to 2 kWh per hour of use.
This is considerably lower than a comparable ducted reverse cycle system, which typically draws several times that amount to run a compressor. Evaporative cooling relies mainly on a fan and a small water pump, not a refrigeration cycle, which keeps electricity usage lower across the board.
How Much Does It Cost to Run All Day?
Running a mid-size ducted system for 8 hours a day generally costs somewhere between $1.60 and $3.60, based on the per-hour figures above. Stretch that to a full 12 to 16 hours on a hot day, and you’re looking at roughly $2.40 to $7.20.
The exact number depends on fan speed, how many outlets are open, and how hot the day is, since the system works harder when the incoming air is hotter.
How Much Does It Cost Throughout Summer?
Over a Perth summer, running evaporative cooling for around 8 hours a day on most warm days typically adds up to somewhere between $150 and $300 across December, January and February. Households running the system longer each day, or through more of the hotter stretches, will sit toward the higher end.
This is a rough seasonal estimate rather than a fixed figure, since Perth summers vary year to year and usage patterns differ from household to household. It still gives a useful benchmark when comparing against a reverse cycle system over the same period.
How Does Fan Speed Affect Running Cost?
Fan speed has a direct effect on power draw. Running on high speed can use two to three times the electricity of running on low or medium speed, since the fan motor works harder to move more air through the ducting.
A lot of Perth homes get better results running the system on a lower or medium speed for longer stretches, rather than blasting it on high for shorter bursts. It’s usually gentler on the system too, and cooling still reaches most rooms effectively at a steady, lower speed.
How Much Does the Water Cost?
Water use is a small part of the overall running cost. A typical evaporative cooling unit uses somewhere around 10 to 15 litres of water per hour, depending on system size and fan speed.
At standard Perth water rates, this generally adds up to just a few cents per hour, or roughly $2 to $5 a month for a household running the system regularly through summer. Water use is a minor factor compared with electricity, but it’s still worth factoring in if you’re budgeting a full seasonal cost.
Is Evaporative Cooling Cheaper Than Reverse Cycle?
In most cases, yes. Evaporative cooling running costs are generally lower than ducted reverse cycle systems, mainly because evaporative units rely on a fan and water pump rather than a compressor-based refrigeration cycle, which uses considerably more electricity to operate.
Reverse cycle systems do offer heating as well as cooling, and give tighter control over indoor temperature. But for straight cooling through a Perth summer, evaporative cooling generally works out cheaper to run, particularly on dry, hot days where the system performs at its best. Our evaporative air conditioning and residential air conditioning pages go into more detail on how the two systems compare.
Does an Older Unit Cost More to Operate?
Generally, yes. As an evaporative cooling system ages, worn pads, a weaker water pump, or a motor that’s not performing at full efficiency can all make the system work harder to deliver the same cooling. That extra strain usually shows up as higher electricity use over time.
An older unit that hasn’t been serviced in a while can end up costing noticeably more to run than a well-maintained system of the same size, simply because it’s less efficient at doing the same job.
Can Servicing Reduce Running Costs?
Yes, and it’s one of the more overlooked ways to keep evaporative cooling running costs down. Clean cooling pads, a properly working water pump, and good airflow all help the system cool effectively without the fan or pump working harder than it needs to.
A service typically checks the cooling pads, water distribution, fan operation, and general condition of the unit. Left unchecked, small issues like clogged pads or uneven water flow tend to get worse, quietly pushing running costs up along the way.
Is It Cheaper to Leave It Running All Day?
It depends on how you use it. Running evaporative cooling continuously on a lower or medium fan speed is often more cost-effective and more comfortable than switching it off and on throughout the day, since the system doesn’t need to work as hard to bring a hot house back down to a comfortable temperature each time.
That said, running it all day still adds up in total hours of electricity use, so it’s not automatically cheaper overall than shorter, well-timed use. The most cost-effective approach for most Perth homes is running the system steadily during the hottest parts of the day, rather than leaving it on overnight when it’s not needed or cycling it aggressively on high speed.
Keep Running Costs Down With the Right System and Servicing
Running costs come down to a mix of system size, fan speed, water use, and how well the unit has been maintained. A well-matched system that’s serviced regularly will almost always cost less to run than one that’s undersized, ageing, or overdue for a check.
If you’re not sure whether your current system is running efficiently, or you’re comparing evaporative cooling against a reverse cycle option before installing, get in touch with our team or call 1300 164 217. We can talk you through what a system suited to your home is likely to cost to run.
