Air Conditioning Running Costs: The Bill After the Install

You've just spent $2,500–$6,000 on a new split system or $8,000–$18,000 on ducted air conditioning. The install went smoothly, the house is comfortable, and then the first electricity bill arrives. For many Australian homeowners, the running cost of air conditioning is a genuine shock — and it's a cost you'll pay every summer (and winter, if you use reverse cycle) for the next 15–20 years.

What it actually costs to run

A typical 2.5kW split system costs roughly $0.40–$0.70 per hour to run at full capacity, based on average Australian electricity prices of $0.30–$0.35/kWh. A 7kW unit for a large living area costs $0.90–$1.50 per hour. Ducted systems serving a full house can draw 8–14kW, costing $2.50–$5.00 per hour when all zones are active.

Over a typical Australian summer — say 90 days where you run the air conditioning for 6–8 hours a day — a single split system adds $200–$500 to your electricity bill. A ducted system serving the whole house can add $800–$2,000 per season. If you also use it for heating in winter, double those figures for a full-year estimate.

Energy ratings are not optional reading

The star rating on your air conditioner isn't marketing — it's the single biggest factor in your long-term running cost. Each additional star represents roughly 15–25% better energy efficiency. Over 10 years, the difference between a 2-star and a 5-star system of the same capacity can be $2,000–$5,000 in electricity costs.

Since 2019, Australia uses the Zoned Energy Rating Label (ZERL), which shows efficiency ratings for three Australian climate zones (hot, average, cold). A unit might rate 4 stars in Brisbane but only 2.5 stars in Hobart. Always check the rating for your specific climate zone, not just the headline number.

Installation quality affects efficiency

A poorly installed split system can use 20–30% more energy than the same unit installed correctly. The most common installation shortcuts that increase running costs include undersized or kinked refrigerant piping, outdoor unit placed in direct sun or poor airflow positions, indoor unit mounted too close to the ceiling restricting air return, and inadequate insulation on the linesets between indoor and outdoor units.

These issues don't just waste energy — they also shorten the compressor's lifespan. The difference between a $600 install and a $1,200 install is often the difference between a system that runs efficiently for 15 years and one that struggles after 5.

How to cut your running costs by 30–50%

The most impactful thing you can do is set your thermostat to 24–25°C in summer instead of 20–22°C. Every degree below 25°C adds approximately 10% to running costs. At 20°C you're paying roughly 50% more than at 25°C for the same hours of operation.

Use timers and smart controls to avoid running the system when no one's home. If you have a ducted system, zone it properly — cooling three rooms instead of six cuts your consumption dramatically. Clean your filters every 4–6 weeks during heavy use. Finally, invest in the building envelope — ceiling insulation, draught sealing, and external shading on west-facing windows can reduce your cooling load by 30–40%.