Reverse cycle air conditioners are the most energy-efficient way to heat and cool your home, but running costs vary significantly depending on where you live, what size unit you have, and how you use it. Whether you're in tropical Queensland running cooling all summer or in chilly Victoria relying on heating through winter, understanding the real costs helps you budget accurately and find ways to save.
Running Costs by State
Climate is the single biggest factor affecting your air conditioning running costs. Hotter states use more cooling energy, colder states use more heating energy, and moderate climates use less overall. Here are estimated annual running costs for a typical 3-bedroom home with a 7kW split system or equivalent:
| State | Primary Use | Annual Running Cost | Usage Pattern |
|---|---|---|---|
| Queensland | Cooling-focused | $400–$700 | Heavy cooling Oct–Apr, minimal heating |
| Northern Territory | Cooling-focused | $500–$900 | Near year-round cooling |
| New South Wales | Balanced | $350–$650 | Moderate cooling and heating |
| South Australia | Balanced | $400–$700 | Hot summers, cool winters |
| Western Australia (Perth) | Cooling-leaning | $350–$600 | Hot summers, mild winters |
| Victoria | Heating-focused | $300–$600 | Moderate heating May–Sep, some cooling |
| Tasmania | Heating-focused | $350–$600 | Significant heating, minimal cooling |
| ACT | Heating-focused | $400–$700 | Cold winters, warm summers |
Running Costs by Unit Size
The capacity of your air conditioner directly affects running costs. A larger unit uses more energy — but an undersized unit running constantly to keep up will also cost more than a correctly sized unit cycling normally.
| Unit Size | Suitable For | Cost/Hour (cooling) | Cost/Hour (heating) |
|---|---|---|---|
| 2.5kW | Small bedroom (15–20m²) | $0.15–$0.25 | $0.12–$0.20 |
| 3.5kW | Bedroom/study (20–30m²) | $0.20–$0.35 | $0.15–$0.28 |
| 5.0kW | Living area (30–40m²) | $0.30–$0.50 | $0.25–$0.40 |
| 7.0kW | Large living area (40–60m²) | $0.40–$0.70 | $0.35–$0.55 |
| 8.5kW+ | Open plan (60m²+) | $0.55–$0.90 | $0.45–$0.70 |
Costs based on 2026 electricity rates of 30–35c/kWh and modern inverter units with COP 3.5–4.5. Actual costs depend on outdoor temperature and thermostat setting.
Ducted vs Split System: Running Cost Comparison
Choosing between ducted and split systems affects both your upfront and ongoing costs significantly:
| Factor | Ducted System | Split System(s) |
|---|---|---|
| Installed cost | $8,000–$15,000 | $1,500–$3,500 per unit |
| Annual running cost | $600–$1,200 | $200–$600 (per unit) |
| Coverage | Whole home | Individual rooms/zones |
| Zone control | Limited (some have zones) | Excellent (each unit independent) |
| Duct losses | 10–30% energy lost in ducts | Nil |
| Aesthetics | Discreet (ceiling vents only) | Wall-mounted indoor units |
Ducted systems cost more to run because they condition the entire home, even rooms you're not using. Energy losses through ductwork — especially if ducts run through a hot roof space — can add 10–30% to your running costs. Zoned ducted systems help, but they're still less efficient than only running a split system in the room you're in.
Tips to Reduce Air Conditioning Running Costs
1. Set the right temperature
The thermostat setting has the single biggest impact on running costs. Each degree of overcooling or overheating adds approximately 10% to your energy consumption:
- Summer: Set to 24–25°C, not 18–20°C. Your body adjusts to a comfortable temperature — you don't need to replicate winter indoors.
- Winter: Set to 18–20°C, not 24–25°C. Wear a jumper if needed. Heating to 24°C costs roughly 40% more than heating to 20°C.
2. Clean your filters regularly
Dirty filters restrict airflow, forcing the compressor to work harder and increasing energy consumption by 15–25%. Clean or replace filters every 3 months during heavy-use seasons — more often if you have pets or live in a dusty area.
3. Improve your home's insulation
Poor insulation means your air conditioner has to work harder to maintain temperature. Key improvements include:
- Ceiling insulation: The most impactful upgrade — reduces heating/cooling loads by 20–30%
- Draught sealing: Seal gaps around doors, windows, and exhaust fans to prevent conditioned air escaping
- Curtains and blinds: Block direct sun in summer and retain heat in winter. Blockout curtains can make a significant difference.
- Window film or double glazing: Reduces heat transfer through glass by 30–50%
4. Use ceiling fans
A ceiling fan costs about 2–3 cents per hour to run — a fraction of air conditioning. In summer, using a ceiling fan allows you to set the air conditioner 2–3°C higher while maintaining the same comfort level, saving 20–30% on cooling costs.
5. Time your usage with solar
If you have rooftop solar, pre-cool or pre-heat your home during the day when solar generation is highest. Many modern air conditioners have timers or smart controls that make this easy. Your home's thermal mass will retain the temperature for several hours after the system turns off.
What Size Air Conditioner Do You Need?
Getting the size right is crucial — both for comfort and running costs. An undersized unit will run constantly trying to keep up, wasting energy and wearing out faster. An oversized unit will cycle on and off too frequently, reducing efficiency and dehumidification.
As a rough guide, you need approximately 120–150W of cooling capacity per square metre of floor area, adjusted for:
- Climate zone (add 20–30% for hot climates)
- Insulation level (add 20–30% for poorly insulated homes)
- Window area and orientation (large west-facing windows add significant heat load)
- Ceiling height (high ceilings increase the volume to condition)
For an accurate sizing calculation, ask your installer to perform a load calculation rather than just estimating based on room size. A properly sized system runs more efficiently, lasts longer, and costs less to operate over its lifetime.