Small split system for a bedroom

Small split system for a bedroom: what matters

A small split system air conditioner for a bedroom has three jobs. It has to suit the room, stay quiet while you sleep and cost little to run.

Here's each one for every split system we install from 1.5 to 3.5 kW. The figures come from the government's energy rating data, so every unit is measured the same way.

What size does a bedroom need?

Start with the floor area: the room's length times its width. Mitsubishi Heavy Industries' sizing chart gives the largest room each size can cool. It depends on which way the room faces.

The north and east columns are for an insulated brick or brick veneer home with shades on the windows. The west column is for a room with little or no insulation and big windows the sun gets into.

Say your bedroom is 4 by 4 metres. That's 16 m². Facing north, a 2 kW unit covers it. Facing east, you'd need a 2.5 kW. Our size guide goes into more detail.

How loud is it while you sleep?

Every energy label shows how loud the indoor unit is, in decibels. Lower is quieter. Mitsubishi Electric's split systems brochure explains that it's measured the same way for every unit: cooling, with 35°C outside and 27°C inside.

The smaller units tend to be the quietest:

The NSW EPA says a change of 2 dB or less usually isn't noticeable, 3 dB is just noticeable and 5 dB is clearly noticeable. So a unit within 2 dB of the quietest is, to your ear, about as quiet.

Our guide to the quietest split systems explains why a brochure can print a much lower number.

What a summer of cooling costs

Each label also gives the energy a unit uses over a whole cooling season. For Sydney's climate zone, the government works it out on the weather in Richmond, NSW. We've priced it at 31.79 cents a kWh.

So at 2.5 kW, the cheapest and the dearest are $24 a summer apart.

What one very hot night costs

An air conditioner doesn't have to run flat out. Every unit in these lists is registered as variable speed, which means an inverter. Mitsubishi Electric's brochure explains what that does: it reads the unit's sensors and changes the compressor's speed, so it uses less power.

The government tests each unit at full output and again at about half. Half power means half the cooling: about 1.25 kW from a 2.5 kW unit. Think of a car cruising instead of flat out.

We've run that half power figure for 8 hours and priced it the same way. The test is done with 35°C outside, so it's the cost of a very hot night.

One hot night doesn't rank units the way a summer does. The Rinnai T Series 2.5 kW costs the least for a summer and the most for a 35°C night. The summer figure covers a whole season of weather, so it's the better guide to your bill.

Quiet and cheap to run: the units that do both

You don't have to pick between quiet and cheap. Here's every 2.5 kW unit within 2 dB of the quietest, the gap you wouldn't notice, cheapest summer first.

Under 2.5 kW, the TCL BreezeIN 2.0 1.7 kW is both the quietest, at 48.8 dB, and the cheapest summer, at $37.

At 3.5 kW, the Fujitsu Lifestyle is 2 dB off the quietest and costs $75 a summer. That's $18 less than the quietest, the Mitsubishi Electric MSZ-EF.

The Panasonic RZ we list isn't in the government's energy rating data, so it isn't in any of these figures.

When it's not running

A split system draws a little power even when it isn't running. The government records this as standby power, and a bedroom unit can sit idle for much of the year.

Left on standby all year, at the same rate:

• Lowest: the ActronAir Serene 2.6 kW, 0.44 W, about $1.23 a year
• Highest: the MHI Ciara 1.5 kW and 2 kW, 6.5 W, about $18.10 a year

The 2.5 and 3.5 kW model pages compare it with the other units at the same size.

Choosing yours

Here's the order we'd go in:

• Size: measure the room and note which way it faces.
• Noise: at that size, look for a unit within 2 dB of the quietest.
• Running cost: compare the summer cost. If you'll heat with it too, our guide to heating costs in a Sydney winter has the winter side.

The outdoor unit makes noise too, and in NSW there are hours when it shouldn't be heard inside a neighbour's home. Our quietest split systems guide covers both.

Not sure what suits the room? Send a few photos through our quote form and we'll tell you what your home can take. Sometimes that takes a visit.

Sources

• GEMS registered air conditioners dataset (E3 program), data.gov.au, CC BY 3.0: each unit's indoor noise, cooling season energy for the mixed climate zone, standby power and half capacity test at 35°C, from the file of 1 November 2026. The same page holds the air conditioner data dictionary (September 2019), which says what each figure means.
• Energy Made Easy, the AER's plan data: the median usage rate across 170 Ausgrid plans, September 2026, with GST added: 31.79 cents a kWh.
• Mitsubishi Heavy Industries split systems brochure: the sizing chart, cooling rows for 1.5 to 3.5 kW and the room classes.
• Mitsubishi Electric split systems brochure 2025: the label's noise figures are measured cooling at 35°C outside and 27°C inside, and what an inverter does.
• NSW EPA, Noise Guide for Local Government (2023): how changes of 2, 3 and 5 dB sound.
• Our split catalogue on 11 November 2026: 54 models from 1.5 to 3.5 kW.