Aircon running cost calculator

What actually moves the number

You pay for running time, so anything that makes the compressor run longer costs more, whatever the sticker on the unit says. Three things do most of it.

• The temperature you set. Holding a room at 18 takes far more running than holding it at 25, and the difference compounds over a month of nights.
• How clean the coil and filter are. Restricted airflow means the room cools slowly, so the unit stays on longer to reach the same setting. This is the one that creeps up without anyone noticing.
• Heat arriving from outside. Afternoon sun on the wall, a room under the roof, an open door to a hot kitchen. Our size calculator counts these when picking a horsepower, and they carry straight through to the bill.

1. 1 The temperature you set. Holding a room at 18 takes far more running than holding it at 25, and the difference compounds over a month of nights. A decision, so it can be changed tonight.
2. 2 How clean the coil and filter are. Restricted airflow means the room cools slowly, so the unit stays on longer to reach the same setting. This is the one that creeps up without anybody noticing and the only one of the three a service call removes.
3. 3 Heat arriving from outside. Afternoon sun on the wall, a room under the roof, an open door to a hot kitchen. A fact about the house, which is why it belongs in the sizing rather than in the remote.

Typical draw by size

Typical ranges for units sold in the Philippines, the same figures the size calculator uses. Your own unit's nameplate is the one that counts.

Questions people ask

How much electricity does an aircon use per hour?

A 1.0 HP non-inverter draws around a kilowatt while the compressor is running, so roughly one unit of electricity an hour. An inverter of the same size pulls less once the room has reached temperature, because it slows down instead of switching off and on.

Does the temperature setting change what it costs?

Yes, and it is the cheapest change available. The compressor runs longer to hold a colder room, so every degree lower is more running time. Setting 24 or 25 rather than 18 usually costs noticeably less over a month, and most people cannot tell the difference once they are asleep.

Is it cheaper to switch the aircon on and off, or leave it running?

For a non-inverter, switching it off when you leave the room genuinely saves, because it only draws power while it runs. For an inverter, short absences are better ridden out: it uses most of its electricity pulling the room down to temperature, so making it do that again costs more than holding it.

Why is my bill higher than this estimate?

Usually because the unit is running more hours than it was supposed to. A dirty filter, a coil that has never been washed, or a room getting afternoon sun all make it run longer for the same temperature, and running time is what you pay for. That gap between the estimate and the bill is often the clearest sign a clean is overdue.

Does an inverter really use less?

It uses less to HOLD a temperature, which is most of the day in a room that stays occupied. It is not cheaper for short bursts, because the pull-down at the start costs about the same either way.