What Setting Your Aircon to 25°C Actually Does to Your Bill (and Your Comfort) in a Singapore Flat

A family in a Sengkang HDB called us in May because their electricity bill had jumped and the master bedroom still felt sticky at night. They had the aircon set to 18°C. Not 25, not 23. Eighteen, all night, because in their words, “25 degrees does nothing, the room is still not cool.”

We opened the fan coil. The reason 25°C did nothing was sitting right there. The coil and blower wheel were furred with a grey biofilm, the kind that builds up when a unit runs hard for a year without a proper clean. A coil in that state cannot pull the water out of the air. So the room stayed damp, the family chased comfort by dropping the temperature lower and lower, and the compressor ran flat out every night. We did a chemical wash at $120. That week they set it back to 25°C, put the ceiling fan on, and told us the room finally felt dry and cool. The bill came back down the next cycle.

That job is the whole point of this article. Singapore is being told to set the aircon to 25°C, through the national Go25 movement and repeated NEA advice. The number is good advice. But whether 25°C feels comfortable or feels like a warm, clammy box has almost nothing to do with the number on the remote. It comes down to two things the remote cannot fix, and we will get to both.

First, the money.

What 25°C actually saves you

Electricity in Singapore is the most expensive it has been. The SP Group regulated tariff for July to September 2026 is about 34.78 cents per kWh with GST, a record high after a 17% jump in July. Every hour your compressor runs at full tilt now costs more than it did last year. That is exactly why the setpoint matters.

Here is the simple math for one bedroom, in plain numbers.

A single bedroom inverter unit, the 9,000 to 12,000 BTU size most HDB rooms use, draws roughly 0.8 kWh in an hour once the room is cool. At today’s tariff that is about 28 to 30 cents an hour. Run it eight hours a night and that one room costs around $2.40 a night, or about $70 a month.

Now drop it from 25°C to 23°C. Every degree below 25 adds roughly 6 to 10 percent to the running cost, because the compressor works harder and rests less. Two degrees lower is around 15 to 20 percent more power. That same bedroom now costs closer to $84 to $86 a month. So chasing two extra degrees of cold costs that one room about $12 to $15 a month, or $150 to $180 a year. Multiply that across a flat running three or four units every night and the gap gets serious.

This is not a guess. When CNA’s Talking Point tested it, moving a household from 22°C to 25°C cut the aircon’s energy use by 34 percent, about $278 saved in a year. In the Go25 office study run with Ngee Ann Polytechnic, raising the setpoint from 23°C to 25°C saved up to 12 percent per degree, and nobody reported feeling less comfortable.

So yes, 25°C saves real money. The catch is the part nobody explains.

Why 25°C feels hot to some people (and how to fix it)

When a customer tells us 25°C is “not cold enough,” they are almost never wrong about how it feels. They are wrong about the cause. The problem is not the temperature. It is airflow and humidity.

Airflow first, because it is free. Moving air across your skin makes you feel three to four degrees cooler than the actual room temperature. This is why a room at 25°C with a fan running feels better than the same room at 22°C with still, heavy air. A ceiling fan or a standing fan uses a tiny fraction of the power an aircon compressor draws. Run the fan, set the aircon to 25°C, and you get the comfort of a much colder room at a fraction of the cost. This single habit is the cheapest cooling upgrade in your home.

Humidity second, because this is the real culprit. Singapore air is wet. What actually makes a room feel fresh and cool is not just cold air, it is dry air. A healthy aircon does two jobs at once. It cools, and it pulls moisture out of the room and drains it away. When people say 25°C feels clammy, what they are feeling is a unit that has stopped doing the second job.

And here is the part we see every week. A unit stops dehumidifying properly when the coil is dirty, when it is low on gas, or when it short cycles. A coil packed with biofilm cannot absorb moisture. A unit low on refrigerant never runs a long enough cycle to dry the room. So the air stays humid, the room feels sticky at 25°C, and the homeowner does the natural thing and drops the temperature to 20 or 18, paying record-high tariffs to fight a problem that a proper service would have fixed.

That is the Sengkang family. That is most of these calls.

Two more real jobs that prove the point

A condo tenant in Bedok told us the aircon was “eating electricity” and never getting cold. The unit ran non-stop and the bill was climbing even though they kept it at 24°C. We put gauges on it and found a slow refrigerant leak. The system never built enough cooling to satisfy the thermostat, so the compressor simply never switched off. We found the leak, repaired the joint, pressure-tested it, and regassed with R32. After that the unit held 25°C easily and rested between cycles. The running cost dropped because the aircon finally did its job in a normal cycle instead of grinding all night.

A retiree in Bukit Panjang was cooling the living room at 21°C every afternoon because it felt stuffy otherwise. There was nothing wrong with her unit. The room just had no air movement and strong afternoon sun on the window. We suggested a $40 ceiling fan and a light blackout curtain, and a general service at $35 to clear a mildly dusty coil. She now sits at 25°C with the fan on and says it feels better than 21°C ever did. Total spend under a hundred dollars, and her afternoon aircon cost roughly halved.

The honest pricing, and what we will not do

Comfort at 25°C is usually a small bill, not a big one. Here is where the common fixes land.

Here is what we will not do. We will not tell you to buy a new aircon when a $120 chemical wash brings the old one back to life. That is the easiest upsell in this trade and we do not make it. We will not top up your gas without finding the leak first, because a unit that leaks gas will feel clammy and run non-stop again within weeks. And we will not “service” a unit while ignoring the outdoor condenser, because a heat-clogged condenser makes the whole system work harder at any setpoint. If your aircon is more than a few years old and you are thinking of replacing it purely for efficiency, ask about NEA Climate Vouchers first and let us check whether a service fixes it for a tenth of the price.

The simple takeaway

Setting your aircon to 25°C is the right move, and at today’s tariffs it saves a household real money, roughly $150 to $280 a year depending on how many units you run and how low you were going before. But the number on the remote is only half the story. If 25°C feels hot in your flat, the answer is almost never to set it lower. The answer is to add air movement with a cheap fan, and to make sure your unit is actually dehumidifying, which means a clean coil and the right amount of gas.

Get those two things right and 25°C feels cool, dry, and comfortable. Get them wrong and you will keep paying premium tariffs to run a struggling unit at 18 degrees. If your aircon feels sticky at 25°C, that is the unit asking for a service, not a colder setting. Call or WhatsApp us on 9654 0044 or 9644 0652, or email sales@vdairconservices.com, and we will make 25°C feel the way it is supposed to.

VD Aircon Services has installed and serviced more than 40,000 units across Singapore since 2016. We are BCA-registered and NEA-registered for refrigerant handling, and we service every major brand for HDB, condo, landed and commercial properties islandwide. Office: 11 Mandai Estate #02-04 ELDIX, Singapore 729908. Call or WhatsApp 9654 0044 or 9644 0652, or email sales@vdairconservices.com.

Team Vedha

We specialize in Aircon installation, repair, and service. We have all type & model of recon compressor, full set & fancoil. Our technicians are highly proficient in their respective field and repairs and fixes aircon of various brands.