What aircon temperature saves electricity?

The aircon temperature to save electricity

The National Environment Agency (NEA) gives one clear figure in its energy saving tips for households: set the aircon at 25 degrees C. Its reason is simple: "the lower the temperature setting, the more energy used by your air-conditioner." A colder setting on the remote means more electricity, not less.

If 25 degrees C feels warm at first, try the other tips below before you lower the setting. None of them asks the aircon to run colder.

Settings that use less power

NEA's household tips make a short routine you can follow each time you switch the aircon on.

1. Set 25 degrees C. Choose 25 degrees C on the remote rather than a lower setting, since lower settings use more energy.
2. Use a fan where you can. Use a fan instead of the aircon to keep cool when that is enough. If it is not, run the aircon for about an hour, then switch to a fan.
3. Switch off early. Set the aircon timer to switch off half an hour earlier than usual. The room stays cool for a while after the aircon stops.
4. Keep the sun out. Close curtains or blinds during the hottest part of the day, or use solar window film.

Eco, sleep and fan modes

Many aircon remotes have modes such as eco, sleep or fan. What each mode does differs from model to model, and none of the official sources on this page rates how much electricity these modes use or save. Read the remote's guide and your unit's manual to see what each mode changes.

Filters and servicing

NEA's household tips say to check the aircon filter once a month and to clean or replace it when necessary. NEA also advises servicing aircon units regularly and getting them inspected once a year.

Daikin gives a shorter interval for its own units. In its guide to cleaning your air-con, Daikin says to clean the filter every two weeks: open the front grille, take out the filter, wash it gently with mild soap and lukewarm water, rinse it, let it dry completely and put it back. Daikin says not to use any cleaning agent other than mild soap.

For another brand, check its manual for the interval it gives. Our guide on how to clean an aircon filter walks through the job, and how often to service an aircon covers servicing intervals.

Choosing an efficient aircon

If you are shopping for an energy saving aircon, start with the Energy Label. NEA's Energy Label rates efficiency in ticks from 1 to 5 and covers casement, window, split type (non-inverter), split type (inverter) and portable aircons. Portable aircons are rated only from 1 to 2 ticks. The label also shows annual energy consumption in kWh, an annual energy cost worked out on fixed assumptions (8 hours of use a day plus 16 hours on standby) and the cooling capacity in kW.

NEA's tips on buying energy-efficient appliances say appliances with more ticks are generally more energy efficient. NEA suggests looking at life cycle cost, not just the purchase price: the purchase price plus the annual energy cost multiplied by the unit's lifespan in years.

NEA's tips on buying energy-efficient appliances also say to choose the right cooling capacity. An oversized unit costs more to run and may not dehumidify well because it cools too quickly, while an undersized unit does not cool or dehumidify adequately. NEA's rule of thumb is that the capacity you need in kW equals the total aircon floor area in square metres divided by 5. Rooms with a double ceiling height, a large window area, windows facing the sun or extra heat sources may need a larger unit. For a detailed assessment, NEA says to consult your aircon supplier.

Our guide to aircon size for your room walks through the sizing. See inverter vs non-inverter aircon to compare compressor types, and aircon types for the main kinds of unit.

Checking what it costs you

SP Group publishes the household electricity tariff and revises it every quarter. Check the current tariff on SP Group's site rather than relying on a figure you saw earlier.

The annual energy cost on NEA's Energy Label uses NEA's fixed assumptions, not the current tariff, so treat it as a way to compare models rather than a forecast of your bill. To compare two aircons, look at the annual energy consumption in kWh on each label: the lower figure means less electricity under the same assumptions. To estimate an appliance's running cost, use the electricity cost calculator. For your aircon, try the aircon running cost calculator.

When to stop and call a professional

Settings help a unit that is working properly. They will not fix a fault. Book servicing or a repair if you notice any of these signs:

• The room no longer cools down on an aircon 25 degrees C setting.
• Ice forms on the pipes.
• Water leaks from the unit.
• The unit makes unusual noise.

Our aircon not cold guide covers what to look at first. What a technician charges depends on the job, so compare aircon servicing prices before you book. For units, servicing and repairs in general, see aircon in Singapore.

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