Can’t live without air-con but worried about costs? Here’s how to use it better

In Singapore’s heat and humidity, air-conditioning is practically a daily essential. Whether you’ve just collected the keys to your new apartment or are thinking about replacing an ageing air-conditioning system, choosing and using the right setup can make a significant difference to your comfort, electricity bills and long-term maintenance costs.

But many households still end up overcooling rooms, wasting energy or overlooking simple habits that could help their systems run more efficiently. From learning the best temperature settings for day-to-day use to deciding how many units your new home needs, there are several smart ways to optimise your air-conditioners’ cooling effort. 

CNA Lifestyle speaks to Daikin Airconditioning’s training manager Eric Tan Kuo Hon about how you can get the most out of your air-conditioning system, while keeping costs, odours and maintenance issues under control.

YOU WANT YOUR APARTMENT TO BE COOL WHEN YOU GET HOME

Activate the air-conditioner via a smart home app about 15 to 30 minutes before you reach home, advised Tan. The recommended setting? A temperature of 25°C with a medium-speed fan. 

Pre-cool only the rooms you will use immediately. That would typically mean the living room (if your family gathers there) and bedroom (if you usually rest there after coming home). “Cooling unused rooms is like running extra light bulbs you’re not looking at,” said Tan, “It adds to the bill without improving comfort.”

For homes not linked to an app, set the air-conditioner at 23°C or 24°C for about 10 to 15 minutes for a quick initial cool-down, then return to 25°C, he said. “Avoid using 18°C as it doesn’t cool the interior faster. Most units cool at a similar rate; they just run longer – and cost more – to reach a lower setpoint.”

For your apartment to feel cooler without dropping the thermostat, switch on a ceiling or standing fan at the same time. Once the room is comfortable, you can even raise the temperature to 26°C and continue using an external fan for air movement. 

You can help your air-conditioner along by keeping the doors and windows closed. Draw the curtains, especially for rooms with west sun. 

To prep your bedroom for sleep without even switching on the air-conditioner, close your blackout curtains at around 5pm or 6pm – especially if the room faces west. Before bed, set the temperature at 25°C with a fan, rather than 22°C all through the night, Tan recommended. And use the sleep or econ mode. “These modes typically ease the compressor load after the initial cool-down,” he said.

YOU DON’T WANT THE BILLS TO BURN A BIG HOLE IN YOUR POCKET

Most people know about National Environment Agency’s energy efficiency rating that awards appliances with one to five ticks. The higher the number of ticks, the more efficient the air-conditioner model is at converting electricity into cooling for its class. But how does it translate into dollars and cents?

Take, for example, cooling a typical HDB bedroom with a split-inverter air-conditioner for eight hours. That often uses around 4kWh to 8kWh, said Tan. Using Singapore’s household electricity tariff for April to June 2026 as reference (about 30 cents per kWh, with GST), it’ll cost you about S$1.20 to S$2.40 per night, he said, or S$36 to S$72 a month. 

So, if a model uses 150kWh a year less than another model, that’ll save you about S$45 annually – before considering differences in usage patterns, said Tan. 

You’ll also save on your household electricity bill by using the timer or sleep mode, which means the air-conditioner doesn’t run at full load in the early morning when the room is already cool, said Tan. “Many households see a noticeable drop in their bills by moving from 22°C to 25°C with a fan and a two-to-three-hour timer; the comfort level is similar but the compressor cycles less.”

Other practical methods include closing the doors, sealing obvious gaps under the doors and cleaning the filters regularly, he added. 

YOU WANT YOUR HOME TO SMELL CLEAN AND FRESH

The air-conditioner itself doesn’t produce pollutants, said Tan, but it can trap and recirculate what’s already indoors, such as fine dust, cooking fumes, pet dander, and volatile organic compounds from new furniture, paint, air fresheners and cleaning agents, he said. 

Then, there’s the musty odour you smell when the air-conditioner is switched on, which essentially, is caused by a combination of moisture and trapped dust, skin flakes and cooking aerosols that settle on the cooling coils and nearby fabrics, explained Tan. Even a newly renovated flat can have lingering odours if you have the air-conditioner on 24/7 with the windows closed.

“When the air-conditioner runs, condensation forms; if parts stay damp for long periods, they encourage microbial growth that can produce odours,” Tan said. “Dampness is also a sign that moisture is being introduced faster than the air-conditioner can remove it.” 

A quick way to minimise the odour and moisture – without expensive upholstery cleaning and spending on a dehumidifier – is to ventilate your apartment daily. Open the windows for 10 to 15 minutes in the morning when the air outside is cooler, suggested Tan. 

It also helps to avoid overcooling or using very low setpoints, he said. “It can make surfaces cold enough for condensation to form when someone opens the door.” And use a fan to keep air moving, especially in stagnant corners where dampness lingers. “Make sure the condensate drainage is working as a slow drain can leave the unit wetter.”

“If your unit has a coil-dry or mould-proof function, use it,” he said. “Otherwise, run fan-only mode for 10 to 20 minutes before switching off to dry off internal moisture.”

Other quick tips include not drying your wet laundry in the room when the air-conditioner is on, and keeping the filters clean so that the system dehumidifies efficiently.

YOU DON’T WANT TO OVERSPEND ON MAINTENANCE 

For most households, regular servicing and filter washing are enough, said Tan. “Washing the filters yourself is excellent – and recommended – but it doesn’t fully replace professional cleaning."

That’s because “the filters mainly catch larger dust particles but over time, fine particles and oily residue, especially in homes that cook often, can build up on the coil, fan or blower, and drainage system", Tan explained. "When these parts are dirty, you can experience a weaker airflow, higher energy use, odours or water leakage – even though the filters look clean.”

As for chemical washing, Tan advised to reserve it for specific problems such as a weak airflow, persistent odour, water leakage or when the coil is heavily clogged. “Chemical cleaning usually means using specialised cleaning solutions to break down stubborn grime on internal components such as the evaporator coil, blower wheel and drainage tray – areas that simple wiping can’t reach.”

His suggestion: Schedule routine servicing every three to six months – more regularly if you use them daily, have pets or live near construction. Get the outdoor condenser checked and cleaned about once a year – or sooner if it’s exposed to dust, leaves or lint. Call for chemical cleaning only when the abovementioned signs appear, or when the technician recommends it upon inspection. Alternatively, consumers can opt for greener methods such as steam cleaning.

YOU WANT TO OPTIMISE YOUR HOME’S AIR-CONDITIONING SYSTEM

Consider replacement when you see a pattern of frequent faults, weak cooling despite proper servicing, unusual noise, water leakage that keeps recurring, or rising electricity bills for the same usage, advised Tan. 

“In Singapore’s daily-use reality, many residential split systems last around eight to 12 years with reasonable maintenance. But heavy use, poor ventilation around the condenser, or chronic dirt build-up can shorten that.” 

Tan suggested replacing the most-used rooms first, such as the bedrooms, “because that’s where you’ll feel the savings and comfort improvement fastest”. “However, also compatibility matters,” he said. 

“If you’re on a multi-split system, replacing only some indoor units may not make sense, unless the outdoor unit and refrigerant system are compatible with the new indoor models. A technician should confirm what can be mixed safely.”

If you’ve just received the keys to your new apartment, it’s a good idea to consider how you’ll be using the cooling system. Tan advised to “right-size” rather than add more air-conditioning units after moving in. 

For instance, he said, think about which rooms would require regular cooling, and consider their size and heat load (is there a west sun, large windows or high ceilings?). Will the rooms be kept closed? Do you intend to convert the room for the baby or into a work-from-home space in the future?