Glossary · Air conditioning
What is an inverter air conditioner?
An inverter air conditioner has a compressor whose speed can rise and fall to match the heat the room needs. A fixed-speed unit can only run flat out or switch off. By modulating instead, an inverter unit holds a steadier temperature, avoids repeated start-ups and generally uses less electricity.
Key points
- An inverter unit changes compressor speed to match demand. A non-inverter unit has one setting and controls temperature by stopping and starting.
- Daikin says inverter units can use up to 30 percent less electricity than non-inverter systems, and its figure comes from the manufacturer.
- Daikin puts the upfront cost of an inverter unit 20 to 35 percent higher on average, which it says savings can offset over time.
- Steadier running also means fewer temperature swings and, Daikin says, quieter operation.
- Daikin says inverter technology is now commonly used in modern air conditioning, so compare the SEER and SCOP on each label.
How an inverter air conditioner works
An inverter is a device that controls the voltage, current and frequency supplied to a motor.[2]Daikin UK, What is inverter technology? In an air conditioner it drives the compressor. Instead of the compressor being either on or off, the inverter alters its speed, so the output can be turned up or down.[2]Daikin UK, What is inverter technology?
Daikin explains the older approach this way. A non-inverter unit has a fixed cooling and heating capacity, because its compressor has one operating mode and cannot be adjusted. It controls the room temperature by stopping and starting repeatedly.[2]Daikin UK, What is inverter technology? Power use rises sharply at every restart, which Daikin says makes the average consumption high and can leave large temperature swings in the room.[2]Daikin UK, What is inverter technology?
An inverter unit avoids most of those cycles. It runs hard to bring the room to temperature, then slows down and holds it. Daikin compares the difference to a lamp with an on-off switch against a light with a dimmer.[2]Daikin UK, What is inverter technology?
Inverter against non-inverter
| Inverter | Non-inverter | |
|---|---|---|
| Compressor | Variable speed | Fixed speed |
| Temperature control | Holds a steady temperature | Stops and starts, so temperature can swing |
| Noise | Quieter, Daikin says, especially in silent mode | Louder when the compressor cycles |
| Wear | Less stress from cycling | More wear from frequent starts |
The comparison is based on Daikin’s own guide.[1]Daikin UK, Why choose an inverter air conditioner? Daikin says inverter units can be up to 30 percent more efficient and use up to 30 percent less electricity, and that upfront cost is 20 to 35 percent higher on average.[1]Daikin UK, Why choose an inverter air conditioner? These are manufacturer figures and the real saving depends on how you use the unit. Compare the SEER on each label, because that is a standard test result, and see SCOP for heating.
Example
Nadia is choosing a unit for a south-facing bedroom in Leeds that she will use most evenings through summer. A fixed-speed unit would cycle on and off through the night. An inverter unit would settle at low output once the room cools. Daikin says inverter units suit homes with extended daily use and are often a good option where stable temperature matters.[1]Daikin UK, Why choose an inverter air conditioner? She asks her installer for the SEER of each unit and a sensible capacity in kW, because an oversized unit still wastes energy.
What people get wrong
The word inverter is not a guarantee of low bills. It describes how the compressor is controlled, not how well the whole system is sized, installed or used. Daikin says its modern inverter wall units reach SEER ratings above 7.5, but that is for its own models.
The figure comes from Daikin’s guide to air conditioning types.[3]Daikin UK, Air conditioning types: best AC systems explained
Another mistake is to think the inverter makes sizing less important. A unit that is too big or too small will still run inefficiently. Daikin also advises a professional service every year so the technician can inspect refrigerant levels, electronics and performance.[1]Daikin UK, Why choose an inverter air conditioner? The same principle of matching output to demand appears in a modulating boiler.
The bottom line
An inverter air conditioner varies its compressor speed instead of cycling fully on and off. That gives steadier temperatures and, according to Daikin, lower electricity use and quieter running, at a higher purchase price. Use the SEER and SCOP on the energy label to compare models, and have the unit sized and fitted by a qualified installer.
Common questions
What is the difference between inverter and non-inverter air conditioners?
A non-inverter unit has a fixed-speed compressor that can only run at one setting, so it stops and starts to hold temperature. An inverter unit changes compressor speed, so it can settle at a low output and hold the room steady.
Do inverter air conditioners really use less electricity?
Daikin says up to 30 percent less than non-inverter units, because restarts cause current peaks that raise average consumption. That is a manufacturer figure, so compare the SEER and SCOP on each model's label.
Are inverter units more expensive?
Daikin says the upfront cost is higher, around 20 to 35 percent on average, and that lower electricity use can balance this out within a few years. Actual savings depend on how much you use the unit.
Is the inverter the same as a modulating boiler?
The idea is similar. Both adjust output to demand instead of switching fully on and off. An inverter air conditioner varies compressor speed, while a modulating boiler varies its burner output.
Sources
We cite the original source for every figure: government, regulators, standards bodies and manufacturers' own documents. Each one shows the date we last checked it.
- Daikin UK. Why choose an inverter air conditioner?. Checked 11 November 2026. ↩
- Daikin UK. What is inverter technology?. Checked 11 November 2026. ↩
- Daikin UK. Air conditioning types: best AC systems explained. Checked 11 November 2026. ↩