How to Choose the Right Size and Energy-Efficient Window Air Conditioner for Your Living Space
When it comes to choosing the right size window air conditioner for your living space, there are several factors to consider, including the size of the room, ceiling height, windows, climate, noise level, and maintenance requirements.
In this article, we will discuss different scenarios and case studies that would require different sizes of window air conditioners, as well as how to figure out what size window AC unit someone would need.
We will also provide tips for choosing an energy-efficient window air conditioner and maintaining it properly.
What Size Window Air Conditioner Do I Need?
Factors to Consider When Choosing a Window Air Conditioner
1.Room Size
Measure the width and length of the room to get the square footage, which will determine the appropriate size air conditioner you need.
The general rule is that an air conditioner needs 20 BTUs for each square foot of living space.
2. Ceiling Height
If your room has a high ceiling, add an extra 10% to the cooling capacity for every foot of ceiling height above 8 feet.
3. Windows and Doorways
If your room has large windows or doorways that let in a lot of sunlight, add an extra 10% to the cooling capacity for every window or doorway in the room that faces west.
4. Climate
If you live in a hot and humid climate, you will need a larger unit to keep your space cool and comfortable.
If you live in a dry and arid climate, you may be able to get by with a smaller unit.
5. Noise Level
Look for air conditioners with a decibel (dB) rating of 60 or lower, as these are generally considered quiet enough for home use.
6. Maintenance
Regularly clean and maintain your window air conditioner to ensure that it’s working efficiently and effectively.
This includes cleaning or replacing the air filter, checking for any leaks or cracks, and ensuring that the unit is level to prevent any water damage.

Room Size (Sq. Ft.) | Cooling Capacity (BTUs) |
---|
100-150 | 5,000 |
150-250 | 6,000 |
250-300 | 7,000 |
300-350 | 8,000 |
350-400 | 9,000 |
400-450 | 10,000 |
450-550 | 12,000 |
550-700 | 14,000 |
700-1,000 | 18,000 |
1,000-1,200 | 21,000 |
Choosing the Right Size and Energy-Efficient Window Air Conditioner: Scenarios and Case Studies
Small Bedroom with a High Ceiling and One Large Window
- Room Size: 100 square feet
- Ceiling Height: 10 feet
- Window: One large window facing west
- Cooling Capacity Needed: Based on the square footage alone, an AC unit with a cooling capacity of 5,000 BTUs is needed.
However, accounting for the high ceiling and large window, an extra 10% is added for each, bringing the total cooling capacity to 6,050 BTUs.
Living Room with Multiple Windows and a Sliding Glass Door
- Room Size: 300 square feet
- Ceiling Height: 9 feet
- Windows and Door: Multiple windows and a sliding glass door facing south
- Cooling Capacity Needed: Based on the square footage alone, an AC unit with a cooling capacity of 7,000 BTUs is needed. Accounting for the high ceiling and windows and door, an extra 10% and 30% are added, respectively, bringing the total cooling capacity to 10,010 BTUs.
Small Home Office with No Windows
- Room Size: 80 square feet
- Ceiling Height: 8 feet
- Cooling Capacity Needed: Based on the square footage alone, an AC unit with a cooling capacity of 4,000 BTUs is needed. Accounting for the high ceiling, an extra 10% is added, bringing the total cooling capacity to 4,400 BTUs.
Choosing an Energy-Efficient Window Air Conditioner
To choose an energy-efficient window air conditioner, look for units with an Energy Star rating, as these units meet strict energy efficiency guidelines set by the US Environmental Protection Agency.
Energy-efficient air conditioners use less energy, which can save you money on your electricity bills and reduce your carbon footprint.