Ideal air conditioning temperature: summer, winter and night.
There is no single number that works for every person and situation. As a starting point: 25–26 °C in summer, 20–21 °C in winter and 24–26 °C for sleeping with cooling, adjusting for humidity, clothing, activity, sun exposure and sensor location.
The remote sets a target. The temperature you feel depends on where the sensor measures, airflow, humidity, sunlight and how the air is distributed throughout the room.
The best temperature is a range, not a rigid number
For a home, IDAE considers that 26 °C or more in summer and 21 °C in winter, with suitable clothing, may be enough to maintain comfort. RITE, by contrast, publishes indoor design with an operative temperature of 23–25 °C in summer and 21–23 °C in winter. These are different references: one guides efficient use and the other is used to calculate HVAC installations.
That is why this article does not present 24, 25 or 26 °C as a universal truth. The right setpoint is the highest temperature that keeps you comfortable when cooling and the lowest that keeps you comfortable when heating, without direct draughts or major imbalances between zones.
Air conditioning temperature in summer and winter
The aim is not to create an extreme microclimate, but to offset the thermal load with the smallest necessary difference. A moderate setpoint improves comfort, reduces time spent operating at high demand and avoids excessive temperature contrasts.
In summer: 25–26 °C
For a home, 26 °C is a solid starting point. On very hot days, the system may need time to remove heat stored in walls, ceilings, furniture and the building envelope.
In winter: 20–21 °C
In HEAT mode, a home setpoint of 20–21 °C usually provides comfort without forcing excessively high temperatures.
Temperature and humidity: why 26 °C does not always feel the same
Thermal sensation does not depend on temperature alone. Relative humidity, air speed, clothing and activity affect the body’s ability to dissipate heat. That is why two rooms at 26 °C can feel very different.
The same temperature can feel comfortable or oppressive
When humidity is high, sweat evaporates less effectively and the air often feels more oppressive. With moderate humidity and some air movement, the same temperature can feel much more comfortable.
How much can energy use change per degree?
IDAE indicates that a 1 °C change generates an approximate 7% saving in heating and cooling. This is a rule of thumb, not a universal constant: actual energy use depends on the system, outdoor temperature, insulation, humidity, air leakage and thermal load. In summer, cautiously raising the setpoint when comfort allows reduces demand; in winter, the opposite applies when lowering it. IDAE
Guidance configurator by season and room use
Select the situation closest to yours. The result is an editorial starting point based on the official references in this article; it does not replace measuring the actual temperature or following the manufacturer’s instructions.
Define the context
The same setpoint will not feel equally comfortable in a sunny living room, a bedroom or an office.
Guidance temperature: 25–26 °C.
Home · SummerStart with a moderate setpoint
Let the system stabilise the room and change only one degree if you are still uncomfortable. Before lowering it further, check blinds, filters, fan speed and louvre direction.
General guidance. For vulnerable people or medical situations, individual healthcare advice should take priority.
Temperature for sleeping and overnight
At night, metabolic activity decreases, bedding changes and exposure to the same airflow lasts longer. That is why air direction and fan speed matter just as much as the selected temperature.
Sleep with air conditioning without getting too cold
As practical cooling guidance, a moderate 24–26 °C setpoint, with no direct airflow onto the body and the fan at low speed, helps avoid overcooling. SLEEP, QUIET or night mode may reduce noise and airflow and, depending on the model, gradually adjust the setpoint.
Ideal office air conditioning temperature
In an office, thermal discomfort is not always solved by lowering or raising the overall setpoint. Proximity to diffusers, façades, windows, computer equipment and shaded areas creates different microclimates.
Ranges recommended by INSST
In the absence of thermal radiation and draughts, and with clothing suitable for the season, INSST recommends these air-temperature ranges for offices.
Difference between selected temperature and actual temperature
When you select 24 °C, you are not telling the air to come out at 24 °C or guaranteeing that every point in the room will be exactly 24 °C. You are setting a temperature setpoint that the control system tries to maintain using the available sensor.
System target vs room reading
Some controllers display the setpoint; others may also show the measured temperature. These are different values: the setpoint is the target changed by the user, while room temperature depends on the sensor reading and where that sensor is located.
Why do the temperatures not match?
Guidance diagnosisGuidance diagnosis ready.
This may be normal during start-upIf the thermal load is high, the actual temperature may take time to approach the setpoint. Check doors and windows, solar protection, filters, airflow and whether the system capacity is adequate. If the difference persists once the space has stabilised, the sensor or installation should be checked.
Does setting the air conditioning to 16 °C cool the room faster?
No. The setpoint tells the system what temperature you want to reach; it is not a linear accelerator pedal. In many inverter systems, a large difference between room temperature and the target already causes the system to increase capacity within its limits, but selecting 16 °C does not create more cooling capacity than the model can deliver.
16 °C does not make the system more powerful
Selecting a temperature far below what you actually want does not increase the system’s maximum cooling capacity. The usual result is that the system keeps running for longer as it tries to reach an unnecessarily low setpoint.
AUTO mode: useful, but it does not work the same way on every system
The AUTO symbol does not have one universal logic. On some models it selects cooling or heating; on others it chooses between cooling and dehumidification, or also adjusts fan speed and louvres. That is why the manual for the specific model is the decisive source.
Measure, compare and select
Panasonic Europe documents controls in which AUTO selects the mode based on the set temperature and the room temperature; on other controllers from the same brand, outdoor temperature may also be taken into account. This reinforces the fact that the exact logic depends on the system.
Summary table: what temperature to set in each situation
These ranges summarise the guidance in the article and turn it into a practical usage guide. The “what to check” column helps prevent the setpoint from being interpreted as a solution independent of airflow, humidity and distribution.
| Situation | Setpoint or guidance temperature | Mode | What to check |
|---|---|---|---|
| Home in summer | 25–26 °C26 °C as an efficient starting point. | COOL | Solar protection, filters, doors and windows, fan speed. |
| Home in winter | 20–21 °CWith suitable clothing and well-distributed air. | HEAT | Louvre direction, defrosting, air leakage and stratification. |
| Bedroom in summer | 24–26 °CAvoid excessive cooling over many hours. | COOL / SLEEP | No direct airflow, low fan speed, noise and the overnight outdoor temperature drop. |
| Office in summer | 23–26 °CRecommended comfort range. | COOL | Diffusers, façades, occupancy, equipment and differences between zones. |
| Office in winter | 20–24 °CRecommended comfort range. | HEAT | Seasonal clothing, draughts, cold windows and air distribution. |
| Very hot room | No need to select 16 °CChoose the final temperature you actually want. | COOL + Powerful/Turbo | Available capacity, sunlight, ventilation and maintenance. |
| Spring or autumn | According to actual temperatureActive heating or cooling may not be necessary. | FAN, DRY or AUTO | Humidity, outdoor ventilation and model-specific logic. |
Common mistakes that reduce comfort
Trying to fix everything with the setpoint
If the problem is direct airflow, a sun-exposed façade or a dirty filter, lowering the temperature by another degree does not solve the root cause.
Measuring in the wrong place
A thermometer next to a window, kitchen or air outlet may give a reading that is not representative of the occupied zone.
Confusing COOL and FAN
FAN moves the air but does not necessarily activate the refrigeration cycle. If the room temperature does not drop, check the selected mode.
Blocking the air inlet or outlet
Curtains, furniture or dirt can affect airflow, sensor readings and the system’s ability to distribute energy.
Leaving direct airflow on all night
A moderate temperature can still be uncomfortable if the airflow hits the same part of the body for hours.
Ignoring maintenance
Clogged filters, a dirty coil or an obstructed outdoor unit can reduce airflow and make the system take much longer to stabilise the space.
Check this sequence
Official and technical sources consulted
Traceability matters: each source is used for a specific purpose. Public bodies and regulations support references on comfort, design and workplace conditions; manufacturer documentation is used to explain how modes and controls behave.
IDAE · Recommendations for homes
21 °C in winter, 26 °C or more in summer, the myth of lowering the thermostat excessively and the approximate rule of thumb of 7% per degree.
IDAE · Managing heating at night
Generally recommends turning heating off at night and states that 15–17 °C may be enough to sleep comfortably when in bed and warmly covered.
Consolidated RITE · BOE
Design operative temperature of 23–25 °C and 45–60% RH in summer; 21–23 °C and 40–50% RH in winter.
INSST · Environmental factors
Recommends 20–24 °C in winter and 23–26 °C in summer in offices under the conditions described in the technical guide.
RD 486/1997 · BOE
Sets a range of 17 to 27 °C for premises with sedentary office work or similar; it is a regulatory range, not an optimum comfort range.
Canal Salut · Cooler summer
Used as a Catalan reference for comfort during hot weather and prudent use of air conditioning.
Panasonic Europe · AUTO mode
Shows AUTO logic based on the set temperature and room temperature, and on some controls also outdoor temperature.
Frequently asked questions
What is the ideal air conditioning temperature in summer?
For a home, start at 25–26 °C. IDAE indicates that 26 °C or more, with suitable clothing, may be sufficient; then adjust according to humidity, sunlight, activity and air distribution.
What temperature should you set in winter?
20–21 °C is a good home starting point in HEAT mode. IDAE uses 21 °C as a sufficient reference with suitable clothing.
Is it okay to sleep with the air conditioning on all night?
As practical cooling guidance, you can start at 24–26 °C, with low fan speed or night mode, clean filters and no direct airflow onto the body, adjusting according to actual comfort.
What temperature should an office be?
INSST recommends 23–26 °C in summer and 20–24 °C in winter under normal office conditions. The general legal range is broader and does not automatically equal comfort.
Does setting it to 16 °C make it cool faster?
No. A lower setpoint does not increase the system’s maximum capacity; it mainly prolongs operation while trying to reach an unnecessarily low target. Use Powerful or Turbo if your model has it.
Why does the remote show 24 °C while the thermometer shows 26 °C?
Because 24 °C may be the setpoint rather than the actual reading. Sensor location, sunlight, stratification, the room’s thermal inertia and airflow can also affect the result.
Is the temperature of the air coming out the same as the remote setting?
No. Supply air must be colder or warmer than the room in order to transfer energy. The number on the remote represents the target room temperature.
Is AUTO or COOL better?
In summer, COOL is more predictable. AUTO can be convenient, but its logic varies by model: some systems select cooling or heating by comparing the setpoint with room temperature, while others take additional variables into account. Check the manual.
Is it better to leave the air conditioning on or switch it off?
With inverter systems, a moderate setpoint allows the system to modulate its output during occupied periods. During long absences, it is generally better to switch it off, schedule it or relax the setpoint; there is no universal rule because insulation, thermal load and the system itself all matter.
When should you call a technician?
When the system does not approach the setpoint with the space closed and filters clean, or there is ice, dripping, abnormal noise, error codes, persistent odours or a large and stable difference between the reading and actual conditions.
