How to Lower Aircon Running Costs, Summer and Winter
You don't have to choose between comfort and your electricity bill. Most of the ways to lower aircon running costs come down to a few habits, a little maintenance and, when the time comes, choosing the right equipment.
Eskom and municipal electricity tariffs go up every year, with municipal increases usually taking effect from 1 July, so the cost of running an air conditioner keeps creeping up even if you use it exactly as before. The good news is that the biggest savings usually come from how the unit is set and looked after, not from expensive upgrades.
Set a sensible temperature
Every degree cooler you ask for in summer means the unit has to work harder and longer. Setting 18°C on a hot day doesn't make the room cool much faster; it just keeps the aircon running until it reaches a colder target than you probably need.
For reference, the US Department of Energy suggests a cooling setting of 78°F, which is about 25.5°C, when you're home. You may prefer a degree or two cooler, and that's fine. The point is to pick a comfortable setting and leave it, rather than chasing the coldest number on the remote. A ceiling or pedestal fan alongside the aircon makes a room feel cooler, so many people find they can set the aircon a little higher without noticing.
Keep the cool air in and the sun out
An aircon can only cool the room it's in. If cool air is leaking out through an open door or warm air is pouring in through a window, you're paying to cool the garden.
- Close doors and windows while the unit runs, and keep doors to unused rooms shut so you're only cooling the space you're in.
- Use curtains and blinds on sun-facing glass. In South Africa, north-facing windows get sun for much of the day and west-facing ones take the harsh afternoon sun. Closing curtains or blinds before the sun hits them stops a lot of heat from getting in.
- Mind the heat sources. Ovens, tumble dryers, halogen lights and banks of computers all add heat that the aircon then has to remove.
- Seal the obvious gaps. Draught strips on doors and gaps around old window frames help in both summer and winter.
Let timers and sleep mode do the work
Most modern units have on and off timers, and many have a sleep mode that gradually raises the setpoint overnight in cooling, when your body needs less cooling anyway. Use the timer to switch the aircon off after you've fallen asleep, or to start it a short while before you get home instead of leaving it running all day.
Inverter units behave a little differently. They're most efficient when running steadily at low speed, so for a short absence it's often better to leave one running at a moderate setting than to switch it off and restart it in a room that has heated right up. For longer absences, switch it off.
Quick wins that lower aircon running costs
| Habit | Why it helps | Effort |
|---|---|---|
| Clean filters every few weeks in peak season | Dirty filters restrict airflow, so the unit works harder for the same result | Low |
| Pick a moderate setpoint and leave it | Less time at full power | Low |
| Close curtains on sun-facing windows | Less heat to remove in the first place | Low |
| Use timers and sleep mode | No cooling of empty rooms or over-cooling at night | Low |
| Keep the outdoor unit clear | Lets it release heat properly | Low |
| Book a professional service | Clean coils and correct refrigerant operation keep efficiency up | Medium |
Don't skip maintenance
Clean filters are the cheapest way to lower aircon running costs, and rinsing them takes about ten minutes. Beyond the filters, dust builds up on the indoor and outdoor coils, drains clog and refrigerant leaks slowly reduce cooling. All of these make the system run longer for less result.
A regular aircon service deals with what you can't reach yourself: coil cleaning, drain flushing, pressure checks and electrical checks. If the unit is low on refrigerant, that means there's a leak, and a technician should find and repair it before any regassing. For homes and businesses with several units, a maintenance plan keeps every one on schedule.
Give the outdoor unit room to breathe
The outdoor unit's job is to get rid of heat. When it's boxed in, buried behind shrubs or sitting in a hot corner that traps its own exhaust air, it has to work harder. Shade from a tree, a pergola or the side of the building can help on hot afternoons, but never at the expense of airflow. Keep the clearances in the manufacturer's manual, and don't build a tight cover around the unit.
Choosing equipment that costs less to run
Inverter units
Inverter units vary their compressor speed to match the load instead of switching fully on and off. For rooms where the aircon runs for long periods, that usually means lower running costs and steadier temperatures. Our comparison of inverter vs non-inverter aircons covers the trade-offs in more detail.
The right size
An undersized unit runs flat out and still struggles on hot days. An oversized one cools quickly in short bursts, which can leave the room clammy and is less efficient than steady running. Sizing should come from the room, its sun exposure, insulation and use, which is why a site assessment matters when you're planning an aircon installation.
Replacing a tired old unit
Older units, especially those running on R22, are often less efficient than current models and more expensive to keep going. If yours needs frequent repairs, it may be time to compare the cost of keeping it with the running savings of a newer unit.
Using heating mode efficiently in winter
A reverse-cycle aircon heats by moving heat from outside air into the room rather than making heat from an element. That's why it usually gives you more warmth for each unit of electricity than a bar heater, oil heater or fan heater. A few habits help it work well on Highveld winter nights:
- Don't overdo the setpoint. Set a comfortable temperature, not a tropical one. The same rule applies as in summer: the bigger the gap from outside, the harder it works.
- Expect defrost pauses. On frosty mornings the outdoor unit periodically defrosts itself and the indoor fan may stop briefly. That's normal.
- Close curtains at sunset. Glass loses heat quickly on cold nights, so drawing curtains keeps the warmth in.
For more on getting the best from heating mode, see using your aircon for heating in winter.
If your unit seems to run constantly without keeping the room comfortable, or it's been more than a year since its last service, book a service with ARS or call 0861 995 092. A clean, correctly working system is the simplest way to lower aircon running costs for the long term.
Running cost questions
For long absences, switching off or using a timer saves electricity. For short breaks of half an hour or so, an inverter unit running steadily at a moderate setting is often more efficient than restarting it in a room that has heated up. Non-inverter units are usually best switched off when the room is empty.
Yes. A clogged filter restricts airflow across the indoor coil, so the unit runs longer to reach the same temperature and cooling performance drops. Checking and cleaning filters regularly is one of the easiest ways to keep running costs down.
Usually, yes. A reverse-cycle aircon moves heat from outside into the room instead of generating it from an element, so it typically delivers more heat for the electricity it uses than bar, oil or fan heaters. Its efficiency does drop on very cold nights.
It depends on how many hours the unit runs, how old and efficient the current unit is, and your electricity tariff. Rooms that use the aircon for long periods every day see the biggest benefit. A technician can look at your current unit and help you weigh up repair against replacement.
Get more cooling for every rand
Book an aircon service with ARS and keep your system running efficiently all year.