Plain-English kW sizing for Townsville bedrooms, why oversizing hurts, the tropical factors that bump it up, and running it off solar.
The plain-English kW rule (and why "bigger" isn't better)
The question we get asked most often on quotes is dead simple: what size split system do I need for the bedroom? As a rough starting point, a standard bedroom of around 10 to 14 square metres sits comfortably on a 2.5kW unit, while a larger room or a master with a walk-in and ensuite usually wants 3.5kW. Treat those numbers as indicative only, not gospel. Proper sizing comes from the room dimensions, the aspect, your ceiling height and how well the place is insulated, which is why we measure before we recommend anything.
Here's the part most people get wrong: oversizing is just as costly as undersizing. Drop a big 5kW unit into a small bedroom and it slams the room cold in five minutes, hits the set temperature and shuts off. That short-cycling means it never runs long enough to pull the moisture out of the air, so you're left with a clammy, cold-but-sticky room and a compressor that's constantly stopping and starting. Undersize it and the thing runs flat out all night, never quite getting there, chewing power and wearing itself out. A correctly sized unit runs longer, gentler cycles, and that's what actually dehumidifies and keeps you comfortable. If you want the full rundown on units and install options, our air conditioning services page walks through it.
The tropical factors that bump the number up
Generic online calculators are built for Brisbane or Melbourne, and they'll undersell you up here every time. Townsville's humidity and the brutal build-up before the wet mean your aircon isn't just lowering temperature, it's doing serious work pulling water out of the air. That latent load is real and it's why a room that'd take 2.5kW down south often needs a step up here. Add our long, fierce summers and the fact that nights barely cool off in February, and the unit is working harder for longer than the brochure assumes.
A few things push the number up fast. West-facing bedrooms cop the afternoon sun and bake well into the evening, so they hold heat long after sunset. High or raked ceilings mean more air volume to cool. Poor or ageing ceiling insulation lets the roof cavity radiate heat straight down at you all night. Big windows, dark roofs and rooms over a garage all add load too. In older Townsville homes across suburbs like Cranbrook, Aitkenvale and Heatley we'll often size up a notch to cover thin insulation, whereas a newer, well-sealed build in Idalia or Bushland Beach might sit right on the calculated number. It's why a tape measure and a look in the roof beats a guess every time.
Running it cheaply off solar
The honest catch with bedroom aircon is the running cost on Ergon, especially if you're cranking it overnight through summer. The smartest fix we see is sizing the unit right so it isn't fighting itself, then pairing it with a properly designed solar power system. Townsville gets the sun for it, and a modern split system sipping power during daylight is close to free to run when your panels are carrying the load. Pre-cool the house in the afternoon while the sun's up and you coast into the evening having barely touched grid power.
The snag is that the heaviest bedroom use is at night, after the panels have clocked off. That's where solar battery storage changes the maths, letting you bank cheap daytime generation and spend it cooling the bedrooms overnight instead of buying expensive peak power off Ergon. Whichever way you go, get the electrical side done properly. A new high-output split or a battery often needs a dedicated circuit and sometimes a switchboard upgrade, and our licensed electrical team sorts that as part of the job. Size it right, run it off the sun, and a cool bedroom stops being the thing you dread on the power bill.
Ready to get it sorted?
We handle air conditioning across Townsville and the Burdekin — quoted upfront, installed by our own accredited local team.