Finding the Optimal Thermostat Settings for Maximum Savings
Your thermostat setting is the single most controllable factor affecting your AC electricity bill. The right temperature balance between comfort and efficiency can save you 10-30% on cooling costs without sacrificing comfort. This guide explains the science and provides practical settings for every situation.
The Temperature-Cost Relationship
Every Degree Matters
Research consistently shows that each degree Celsius you raise your thermostat saves 3-5% on cooling costs. This relationship is nearly linear within comfortable ranges:
- Setting at 22°C: Maximum cooling, maximum cost (baseline)
- Setting at 24°C: 6-10% savings vs 22°C
- Setting at 25°C: 9-15% savings vs 22°C
- Setting at 26°C: 12-20% savings vs 22°C
- Setting at 27°C: 15-25% savings vs 22°C
Why Higher Settings Save Money
Lower thermostat settings mean:
- Greater temperature differential between inside and outside
- AC compressor runs longer and works harder
- More electricity consumed per hour of operation
- Faster heat gain when AC cycles off (for non-inverter units)
Optimal Settings by Situation
Daytime (Occupied Home)
| Activity | Optimal Setting | Notes |
|---|---|---|
| Working from home | 24-25°C | Add fan for perceived comfort boost |
| Light activity | 25-26°C | Comfortable for most people |
| Watching TV/relaxing | 25-26°C | Sedentary activity needs less cooling |
| Exercising | 22-23°C | Physical activity generates body heat |
| Cooking | 23-24°C | Kitchen generates extra heat |
Nighttime (Sleeping)
Your body naturally cools during sleep, requiring less AC cooling:
- Optimal sleep temperature: 26-27°C
- With ceiling fan: 27-28°C
- Sleep mode: Gradually raises temp 1°C per hour (very efficient)
Away from Home
- Short absence (1-4 hours): Raise to 28°C
- Long absence (full day): Turn off or set to 30°C
- Extended vacation: Turn off completely
Smart Thermostat Strategies
Pre-Cooling Technique
Cool your home during early morning when outdoor temps are lower and electricity rates may be cheaper. Then raise the thermostat during peak afternoon hours:
- 6-8 AM: Set AC to 23-24°C while outdoor temp is still cool
- 8-10 AM: Raise to 25°C
- 10 AM-4 PM: Maintain 26-27°C (peak heat hours)
- 4-8 PM: Return to 25°C as outdoor temps drop
- 8 PM-6 AM: Sleep mode at 27°C or use timer
Avoiding Common Mistakes
- Don't set to lowest: Setting to 16°C doesn't cool faster—it just runs longer and wastes energy
- Don't adjust frequently: Constant adjustment makes inverter ACs less efficient
- Don't ignore outdoor temp: When it's cooler outside, raise thermostat or use natural ventilation
Comfort vs. Savings Balance
Factors Affecting Comfortable Temperature
- Humidity: Higher humidity feels warmer—consider dry mode
- Clothing: Light clothing allows higher temperature settings
- Air movement: Ceiling fans add perceived cooling of 3-4°C
- Personal preference: Some people naturally prefer cooler/warmer
- Acclimation: Your body adjusts to higher temps over 1-2 weeks
Gradual Adjustment Strategy
If you currently set AC at 22°C, don't jump directly to 26°C. Gradually increase by 1°C per week. Your body acclimates, and you'll soon find 25-26°C comfortable.
Programmable and Smart Thermostats
Benefits of Automation
- Automatically adjusts temperature based on time/schedule
- Learns your preferences and optimizes over time
- Remote control via smartphone when away
- Can save additional 10-15% through consistent optimization
Recommended Schedule
| Time | Weekday Setting | Weekend Setting |
|---|---|---|
| 6 AM - 8 AM | 24°C (wake up) | 26°C (sleeping in) |
| 8 AM - 5 PM | 28°C (away at work) | 25°C (home) |
| 5 PM - 10 PM | 25°C (home) | 25°C (home) |
| 10 PM - 6 AM | 27°C (sleep) | 27°C (sleep) |
Special Considerations
For Children and Elderly
Infants, young children, and elderly may be more sensitive to temperature. Consider settings 1-2°C lower than standard recommendations, and monitor for comfort.
For Pets
Dogs and cats are comfortable at 24-26°C. Avoid temperatures above 28°C when pets are home alone for extended periods.
For Electronics
Computers and electronics generate heat and may require slightly lower temps in home offices. However, don't over-cool—26°C is fine for most equipment.
Measuring Your Savings
To see your actual savings:
- Note your current settings and monthly bill
- Raise thermostat by 2°C for one month
- Compare bills (accounting for weather differences)
- Typical result: 6-10% savings per 2°C increase
Conclusion
Optimal thermostat settings balance comfort with efficiency. The sweet spot for most people is 24-26°C during the day and 26-28°C at night. Combined with ceiling fans and smart scheduling, you can achieve 10-30% savings on AC electricity while staying comfortable.