Optimal Thermostat Settings for Maximum Savings
The single number your finger rests on when you pick up the AC remote has more impact on your electricity bill than almost any other decision you make about how to use the unit. The right setting is not the coldest the remote will allow. It is the highest temperature at which you are genuinely comfortable, and there is real data behind where that sits in Indian conditions.
Quick answer: The Bureau of Energy Efficiency recommends 24 degrees Celsius as the optimal setting for comfort and energy savings in India. Each degree lower than 24 degrees increases electricity consumption by approximately 6 percent. At 20 degrees, you are using roughly 24 percent more electricity than at 24 degrees for the same room and the same hours of use.
Why 24 Degrees Is the Recommended Baseline
The BEE arrived at 24 degrees through a combination of energy efficiency data and human comfort research in Indian conditions. At 24 degrees, most adults in light clothing are comfortable in Indian summer. The room is noticeably cool relative to the outdoor temperature, but the compressor does not need to run as hard or as continuously as it does at lower set temperatures. At 20 degrees, the compressor works significantly harder and longer against the larger temperature gap, often producing a room that feels uncomfortably cold while consuming far more electricity.
This recommendation gained wide recognition after the BEE campaign in 2018 asking building owners to set ACs at 24 degrees. Multiple independent analyses confirmed the 6 percent per degree rule of thumb across a range of common Indian AC sizes and climate zones.
The 6 Percent Per Degree Rule
The approximate electricity saving from each degree you raise the set temperature is 6 percent of the AC's running consumption. Here is what that means across a range of set temperatures:
| Set temperature | Approx. electricity consumption relative to 24 degrees |
|---|---|
| 20 degrees | +24% more than at 24 degrees |
| 22 degrees | +12% more than at 24 degrees |
| 24 degrees | Baseline |
| 26 degrees | ~12% less than at 24 degrees |
| 28 degrees | ~24% less than at 24 degrees |
For a 1.5 ton 5-star inverter unit using 240 units per month at 24 degrees, moving to 20 degrees would add roughly 58 units per month, or about 464 rupees at 8 rupees per unit. Moving to 26 degrees would save about 29 units, or 232 rupees. Over a 4-month peak season, the 24-to-26-degree improvement saves about 928 rupees without any loss in comfort if a ceiling fan is running. See using AC and ceiling fan together for how the fan combination enables the higher set point.
Time-of-Day Setting Strategy
Not all hours of the day have the same heat load. Outdoor temperatures are highest from 2 pm to 5 pm and lowest in the early morning hours. An effective strategy for households that run the AC all day:
- Afternoon (2 pm to 6 pm): Set to 25 to 26 degrees. The room is under peak heat load from sun and outdoor temperature, and the AC is working its hardest. A lower setting barely moves the needle on comfort but adds significantly to the bill.
- Evening (6 pm to 10 pm): Set to 24 to 25 degrees. Outdoor temperature is dropping and the room's heat load is falling.
- Overnight (10 pm to 6 am): Set to 25 to 26 degrees with a ceiling fan on low. The body's own temperature drops during sleep and the room needs less cooling. Use the sleep timer to switch off after 3 to 4 hours.
Using the Sleep Timer
Most AC remotes have a timer that switches the unit off after a set number of hours. Once you are asleep and the room has reached temperature, the AC only needs to run for another two to three hours before the room stays cool enough on its own through early morning, when outdoor temperatures are at their lowest. Setting the timer to switch off after 3 to 4 hours after you go to bed saves 4 to 5 units per night. Over a 120-night season, that is up to 600 units, worth around 4,800 rupees at 8 rupees per unit. For the full detail, see the best AC temperature for sleeping.
Auto Mode vs Cool Mode
On a non-inverter AC, cool mode runs the compressor continuously while auto mode switches it off once the set temperature is reached and back on when the room warms. Auto mode is the correct setting for a non-inverter because it allows the compressor to rest between cycles. Keeping a non-inverter on cool mode in a room that has already reached temperature wastes electricity. On an inverter AC, the compressor automatically slows to a low idle instead of switching off, so the mode distinction is less critical, but auto is still the recommended setting.
Do Not Cool Empty Rooms
This is obvious but frequently overlooked. Switching the AC off when leaving a room for more than 15 to 20 minutes saves more than any thermostat adjustment. A room with no occupants has no benefit from cooling. The slight extra electricity used to cool the room back down on your return is always less than the electricity used to maintain a cool empty room for the duration you were away.
See how much your monthly cost changes with different temperature settings.
Electricity Cost CalculatorKey takeaways
- The BEE-recommended setting is 24 degrees Celsius. Each degree lower adds roughly 6 percent to electricity consumption.
- Moving from 20 degrees to 24 degrees saves approximately 24 percent of the AC's running cost.
- Use the sleep timer to switch off after 3 to 4 hours overnight. This saves up to 600 units over a 120-night season.
- On non-inverter ACs, use auto mode, not cool mode. Auto mode lets the compressor cycle off once the set temperature is reached.
- Switch the AC off when leaving the room for more than 15 to 20 minutes.
Frequently Asked Questions
What is the best AC temperature setting to save electricity in India?
The Bureau of Energy Efficiency recommends 24 degrees Celsius. At this setting, most people are comfortable in Indian summer conditions and the compressor does not run as continuously as at lower temperatures. Each degree below 24 degrees increases electricity consumption by approximately 6 percent.
How much electricity does each degree on the thermostat save?
Approximately 6 percent per degree. Moving from 20 to 24 degrees, a 4-degree change, saves roughly 24 percent of the AC's electricity consumption. Over a 120-night summer season, that is a very significant saving.
Is auto mode better than cool mode for saving electricity?
For a non-inverter AC, yes. Auto mode lets the compressor switch off once the set temperature is reached, which saves electricity. Cool mode on a non-inverter keeps the compressor running continuously. For inverter ACs, the distinction matters less because the compressor automatically slows rather than fully switching off.
Should I use the sleep timer on my AC?
Yes, if you fall asleep within 30 to 45 minutes. Setting the AC to switch off after 3 to 4 hours saves 4 to 5 units per night. Over a 120-night season, that is up to 600 units, roughly 4,800 rupees at 8 rupees per unit.
Sources and Further Reading
- Bureau of Energy Efficiency, India, 24-degree thermostat campaign and guidance (beeindia.gov.in)
- ENERGY STAR, thermostat settings and AC energy savings (energystar.gov)
- U.S. Department of Energy, programmable thermostats and AC efficiency (energy.gov)
The 6 percent per degree figure is an approximation based on BEE guidance and is widely cited for Indian conditions. Actual savings vary with unit model, outdoor temperature, and room characteristics.