Energy-Efficient Air Conditioning: Choose and Run It Smarter

An air conditioner can be the most expensive appliance to run in your home, and an energy-efficient air conditioning system can be the difference between a comfortable summer and a bill that makes you wince. The good news is that choice, installation and daily habits all influence the result, and you control most of them.

This guide covers how to choose the right system, what to ask an installer, and the simple habits that cut running costs.

Size matters more than you think

Bigger is not better. An oversized unit cools the room quickly, switches off, then switches on again, wasting energy and leaving the space clammy. An undersized one runs flat out and still struggles on hot days.

The right size depends on the room's floor area, ceiling height, insulation, window size and direction, and how much sun the space gets. A rule of thumb printed on a box is only a starting point. A reputable installer should assess your actual space, and may ask about things like the number of people using the room and heat from appliances.

Reading the energy label

In Australia, most air conditioners carry an energy rating label that shows efficiency for both cooling and heating. More stars generally mean lower running costs for the same output, although a higher-rated unit usually costs more to buy. Compare the efficiency figures, not just the star count, and think about how many hours a year you will use it.

Inverter or fixed speed?

Inverter models adjust their output to hold a steady temperature rather than switching fully on and off. They are generally more efficient and quieter than fixed-speed units, which is why most new systems use them. For a room you use often, the extra purchase price usually pays for itself over time.

Reverse cycle for heating too

Reverse cycle models both cool and heat, and heating this way can be an efficient option compared with many other electric heaters. If you want year-round comfort, it is worth considering.

Types of systems

• Split system: one indoor and one outdoor unit, ideal for a single room or open-plan area.
• Multi-split: several indoor units connected to one outdoor unit, useful when space for outdoor units is limited.
• Ducted: one central system with vents through the house, suited to whole-home comfort and zoning.
• Portable and window units: lower upfront cost, but usually less efficient and less effective than a properly installed split system.

What to ask your installer

1. Are you licensed for refrigerant handling and electrical work in my state?
2. How did you work out the size for my home?
3. Where will the indoor and outdoor units go, and why?
4. What is included in the quote, including piping, electrical work and removal of old units?
5. What warranty applies to the unit and to your installation work?
6. How often should the system be serviced?

Be cautious about unlicensed operators and quotes that are far below the rest. Poor installation can reduce efficiency, void warranties and cause problems down the track.

Habits that cut running costs

Set the thermostat sensibly. Each degree of extra cooling uses more energy, so choose a comfortable temperature rather than the coldest setting. Many people find a moderate setting is enough, especially with a ceiling fan helping to move air.

Close doors and cool only the rooms you are using. Block heat before it gets in by closing curtains and blinds on sun-facing windows, and consider shade for outdoor units, as long as airflow is not blocked.

Use the timer or schedule so the system runs only when needed. Pre-cooling a room before the hottest part of the day can help, though check what suits your tariff and setup.

Servicing and cleaning

Clean indoor filters regularly, as clogged filters make the system work harder and affect air quality. Keep the outdoor unit clear of leaves, dirt and clutter. Have the system professionally serviced as the manufacturer or installer recommends. A neglected unit uses more power and tends to fail sooner.

Key takeaways

• Choose the right size for the space, not the biggest unit available.
• Compare energy efficiency, and consider inverter reverse cycle models.
• Hire a licensed installer who assesses your home properly.
• Seal, shade and insulate to make cooling easier.
• Clean filters and service the system regularly.