By Steve, co-founder AC Store | Published: 22 September 2026 | Last updated: September 2026
It’s mid-September in South East Queensland. In three months, the aircon will be running six-plus hours a day, and by January’s Energex bill you’ll either be quietly relieved or muttering at the letterbox. The difference is almost never the brand on the wall. It’s whether the system is tuned, sized, zoned and timed correctly, and whether the house is helping or fighting it.
Short version: the four biggest levers, ranked by real dollar impact. (1) Get the unit right-sized and serviced before summer (15–25% saving on a neglected system). (2) If you have ducted, use zoning properly, not just “on” (25–40%). (3) Set 24–25°C and pair with a ceiling fan (7–10% per degree). (4) Time-shift runtime into solar hours if you have rooftop PV (up to 70–80% cost reduction on shifted kWh). Stack all four and a $600 summer bill becomes $250–$350.
We’ve read every “top 10 ways to save on your aircon bill” article on the internet, and most are padded with tips that account for maybe 5% of the actual saving. This is the honest ranking, backed by the maths we run with our own customers across Brisbane, Moreton Bay, the Sunshine Coast and Hervey Bay. Book a pre-summer service if you want step one done this week.
How SEQ aircon actually shows up on your Energex bill
Before we start ranking tips, understand what you’re paying. Almost every SEQ household on the Energex distribution network is on one of four tariffs. Verify current cents-per-kWh with your retailer before running any maths:
| Energex tariff | What it is | Indicative 2026 c/kWh | Can aircon run on it? |
|---|---|---|---|
| Tariff 11 | General residential (flat rate all day) | ~33–37 c/kWh | Yes (the default) |
| Tariff 31 | Controlled load, night-only (~8–10 hrs) | ~22–26 c/kWh | No (too few hours) |
| Tariff 33 | Economy (~18 hrs, controlled) | ~24–28 c/kWh | Rarely for aircon |
| Tariff 41 | Super economy time-of-use | ~14–20 c/kWh off-peak, higher peak | Yes (very high intent; hard to qualify for a residence) |
For the vast majority of SEQ households, your aircon runs on Tariff 11. That’s the number to plan around.
Rough summer draw, at Tariff 11 ~35 c/kWh:
| System | 3 hrs/day, 90 days | 6 hrs/day, 90 days | 9 hrs/day, 90 days |
|---|---|---|---|
| 2.5 kW split (bedroom) | ~$25 | ~$50 | ~$75 |
| 5 kW split (living) | ~$50 | ~$95 | ~$145 |
| 7 kW ducted (small home) | ~$70 | ~$135 | ~$205 |
| 10 kW ducted (full home, unzoned) | ~$95 | ~$190 | ~$285 |
Same 10 kW ducted, zoned to 2–3 rooms instead of the whole house, roughly halves. That’s Lever 2 in action before you even start.
The four biggest levers, in dollar-impact order
Lever 1: Right-size and service before summer (15–25% saving)
The single fastest way to lower your bill is to make sure the system you already own is running at spec. A clogged filter, dirty coil, blocked condensate drain, or slightly low refrigerant charge can each cost 5–15% in extra electricity, and they stack. A system that hasn’t been serviced in three years is commonly running 20–30% harder than it needs to.
A pre-summer service (filter, coil sanitise, drain flush, blower, refrigerant pressures, electrical safety) typically pays back within one or two Energex bills. Our in-house team makes more money selling new units than servicing old ones, and we still recommend a service first every time. If the system is in good shape, we’d rather save you $10,000+ and tell you to ride it out.
Sizing is the flip side. Oversized systems short-cycle, never dehumidify properly, and run 20–30% more expensive than a right-sized unit. The most expensive mistake we see in SEQ is a 10 kW ducted in a 120 m² well-insulated lowset that needed 7 kW. Book a pre-summer service →
Lever 2: Use zoning properly if you have ducted (25–40% saving)
Zoning is the biggest single lever any ducted homeowner has, and it’s the one most people don’t actually use. A four-bedroom family rarely uses every room at once. Cooling the living area and master bedroom while closing off two spare rooms halves the conditioned volume and drops running cost 25–40%.
The mistake we see across Brisbane hallways: homeowners have AirTouch 5, MyAir or Zonemaster installed and leave it on Auto with every zone open forever. Auto is a starting point, not a strategy. Zone off unused rooms, schedule zones around the family’s day, and close bedrooms during work hours. That’s where the savings live.
Lever 3: Setpoint discipline at 24–25°C with a ceiling fan (up to 7–10% per degree)
Every degree cooler on the setpoint adds roughly 7–10% to running cost on inverter units, and more at extremes. Setting 21°C on a 34°C day doesn’t cool the house faster than 24°C; it just costs more because the compressor runs longer at max speed trying to overshoot comfort.
| Setpoint | Relative running cost | Comfort with a fan on low |
|---|---|---|
| 26°C | Baseline | Very comfortable |
| 25°C | +7–10% | Very comfortable |
| 24°C | +15–20% | Comfortable |
| 22°C | +30–40% | Cool, usually unnecessary |
| 18°C | +70–100% | Costly, no comfort gain over 22°C |
The trick: a ceiling fan as a virtual thermostat. A fan doesn’t cool a room; it lets you feel 2–3°C cooler at the same setpoint, at about 1/10th the electricity draw. 25°C plus a fan feels like 22–23°C without one.
Realistic SEQ family schedule: 25°C evenings, 26°C overnight, off during work hours (unless the dog or cat needs it). Living area first, bedrooms an hour before sleep.
Lever 4: Time-shift into solar hours if you have rooftop PV
SEQ has the highest rooftop solar penetration in Australia, and in 2026 most homeowners still haven’t optimised aircon timing around it. The gap is enormous: feed-in typically pays 5–10 c/kWh while Tariff 11 grid power costs 35–40 c/kWh. Running the aircon between 10 am and 3 pm on solar effectively makes those kWh free or near-free.
Practical shape: pre-cool the house hard between 10 am and 3 pm while solar is generating. Thermal mass and inverter modulation then coast the house through the late-afternoon peak with minimal grid draw. A battery (Powerwall, BYD) extends the window further, but even without one the pre-cool alone shifts 40–60% of summer runtime off the grid.
The next-tier tips that still matter
These aren’t rounding error, but they aren’t Lever 1–4 either. Stack them on top of the big four.
Filter cleans monthly through summer. Real 5–15% cooling-output impact when the filter’s clogged. See our companion piece: how to clean an aircon filter.
External shading on west-facing walls. Awnings, shade sails and established plants. Up to 30% of summer cooling load comes from solar gain on west and north glass, and stopping heat at the window is dramatically cheaper than removing it once it’s inside.
Curtains and block-outs on west windows. Second-best after external shading. Honeycomb / cellular blinds are the most effective internal option.
Seal draughts. Queenslanders are notorious. A weekend of weather-stripping recovers 5–10% of your cooling.
Ceiling insulation top-up. Most pre-2000 SEQ homes are under-spec by current standards. Payback typically 5–7 years on aircon savings alone.
Avoid heat sources during peak. Oven, dryer and a wall of downlights fight the aircon. Shift cooking to evenings, use the clothesline, replace halogens with LEDs.
Set fan to Auto on inverter units, not High. Auto lets the inverter modulate; High forces continuous fan draw.
Dry mode is not a cheap cooling mode. It reduces humidity, which feels cooler. Use it on humid-but-not-that-hot 28°C afternoons, not as a substitute for COOL on a genuinely hot day.
When the tips won’t fix it: the honest replacement math
If your unit is 10+ years old, R410A, and needs a compressor or a regas, at some point servicing is money after the fact. The maths is worth running honestly.
Worked example. A 12-year-old 6 kW fixed-speed R410A unit averaging 1,400 kWh over a SEQ summer at Tariff 11 (35 c/kWh) = ~$490. A modern 6 kW R32 inverter drawing ~950 kWh for the same output = ~$333. That’s ~$157/year saved. Over 10 years, the saving ($1,570) pays a chunk of the install, and you haven’t counted the avoided regas ($400–$800 per event) and the reduced service intensity.
Honest triggers to replace, not repair: 8+ years old and needing a second-in-two-years service; R410A unit due for a regas; ducted system with recurring drain and rusted pan; coastal condenser that’s lost 30%+ of fin area to salt.
2026 SEQ indicative install pricing (verify with sales): single-head split supplied and installed $2,500–$4,500; multi-head 3-zone $6,500–$11,000; ducted 4–6 zone $10,000–$18,000; premium ducted with AirTouch zoning $15,000–$25,000.
Our 6–60 month interest-free finance turns a $12,000 zoned ducted upgrade into roughly $200/month at 0%, subject to approval. When the annual running-cost saving on a modern R32 inverter is bigger than the monthly repayment, the new unit pays for itself. Request a free split system quote or ducted quote.
Cowboy-service red flags to avoid: no ARCtick number quoted with a regas, cash-only with no ABN, no written quote, or “we can just top up the gas” without leak testing. Any refrigerant work in Australia requires an ARCtick licence.
SEQ-specific cost traps we see every week
Coastal salt corrosion. On Sunshine Coast, Caloundra and Hervey Bay properties, outdoor coils lose 30%+ of heat-exchange area to salt within 5–7 years and the unit runs twice as hard for the same cooling. Annual coastal service is non-negotiable.
Uninsulated Queenslanders. Weatherboard walls and no ceiling insulation double the cooling load. Sizing has to account for it; insulation is one of the best-ROI upgrades a Queenslander owner can make.
Cheap renovation-era ductwork. Undersized flexi-duct or too many bends = high static pressure = blower fan overtime = higher running cost every hour. If your ducted vents have always felt noisy, get a duct audit.
Rentals under QLD Minimum Housing Standards. Under the standards (all tenancies from 1 September 2024), a rental must be reasonably safe and functional. In SEQ’s climate an efficient reverse-cycle is increasingly expected. Landlords, a $3,000 split install can save a tenant $300+/year in portable-heater and fan costs, and meets the standard.
Frequently Asked Questions
What’s the cheapest temperature to run my aircon at in Brisbane?
24–25°C is the SEQ sweet spot. Every degree lower adds roughly 7–10% to running cost, and comfort gain drops off fast below 24°C. Pairing 25°C with a ceiling fan feels like 22–23°C without one.
Is it cheaper to leave the aircon on all day or turn it on and off?
For modern inverter units, running continuously at 25°C through a hot SEQ day is usually cheaper than repeatedly bringing a hot house back down. For older fixed-speed units, turn it off if you’re out for more than an hour. The middle ground: use timers or AirTouch scheduling to run during occupied hours and let it coast overnight on a warmer setpoint.
How much does it cost to run a ducted air conditioner per hour in Queensland?
Ballpark: a 10 kW ducted at Energex Tariff 11 (~35 c/kWh) draws about $1.20–$2.50 per hour depending on load and how many zones are active. Zoning to only 2–3 rooms drops that closer to $0.50–$1.00. Verify with your retailer’s current rate.
Do inverter aircons really save more electricity?
Yes, meaningfully. An inverter modulates compressor speed rather than cycling on and off. In our SEQ install experience, replacing a 10+ year-old fixed-speed with a same-capacity R32 inverter typically cuts summer electricity 25–35%.
Should I use my ducted aircon zoning to save money?
Absolutely. It’s the single biggest lever a ducted homeowner has. Zone off unused rooms (bedrooms during the day, home office overnight, spare rooms year-round). Homes that use AirTouch or MyAir zoning properly consistently run 25–40% cheaper than those that leave every zone open.
Does running the aircon off solar panels during the day actually save money?
In SEQ, yes, and the gap is large. Feed-in typically pays 5–10 c/kWh while Tariff 11 grid power costs 35–40 c/kWh. Shifting runtime into 10 am–3 pm solar hours turns electricity you were exporting cheaply into free cooling. Even without a battery, pre-cooling the house during solar hours cuts summer grid draw 40–60%.
When is it cheaper to replace an old aircon than keep servicing it?
Rough rule: if the unit is 8+ years old, still uses R410A, and the yearly running-cost delta vs a new R32 inverter beats the annual finance repayment on the replacement, replace. On a typical 6 kW split the crossover point is around the 10-year mark or the second regas event.
Does regular servicing actually reduce running costs?
Yes. A dirty filter, dirty coil, blocked drain or low refrigerant charge can each cost 5–15% in extra electricity; stacked, that’s 20–30% wasted. A pre-summer service typically pays back within one or two summer power bills.
Get us to look at it before summer
Every September, the calls in North Lakes and Kawana shift from “my aircon isn’t cooling” to “how do I stop it eating my power bill this summer?”. The answer is boringly consistent: service and tune first, zone properly, discipline the setpoint, and time-shift into solar hours. Those four levers beat every “top tip” article on the internet combined. Book a pre-summer service and get it locked in before the December rush.
If replacement math looks right, request a free split or ducted quote, or come see current-generation R32 inverters and AirTouch zoning at our North Lakes or Kawana showroom. Companion pieces: aircon not cooling | how to clean an aircon filter.
About the author
Steve is co-founder of AC Store and has spent 15+ years designing energy-efficient air conditioning solutions across Brisbane, Moreton Bay, the Sunshine Coast and Hervey Bay. AC Store: LG National Dealer of the Year 2024–2025, 10,000+ SEQ installs, 400+ verified 5-star reviews (4.9★), three locations. North Lakes and Kawana showrooms plus the Deception Bay warehouse. More about the team.
Published: mid-September 2026 | Last updated: 25 August 2026 | Next scheduled refresh: after 1 July 2027 Energex tariff review