Skip to main navigation.

Ken's Weekly E-Tip: Choosing a Window Air Conditioner

If purchasing a window air conditioner is on your "to-do" list, you may ask what size is needed to do the job. Here is a simple calculation to help answer the question.


Square Footage               

Determine the square footage of a rectangular or square room by multiplying the width by length. Triangular areas are simply calculated by multiplying the length by the width and dividing by two. Sum up all shapes to arrive at total square footage. Ask your sales associate to help calculate square footage if your room is other than a square, rectangle or triangular shape.


Unit Cooling Capacity

Use the square footage chart below to determine what size air conditioner you will need to get the job done. Unit sizes are measured in British Thermal Units (BTU) per hour.

Area to be Cooled (Square Feet) Capacity Needed (BTU per hour)
100 up to 150


150 up to 250


250 up to 300


300 up to 350


350 up to 400


400 up to 450


450 up to 550


550 up to 700


700 up to 1,000


1,000 up to 1,200


1,200 up to 1,400


1,400 up to 1,500


1,500 up to 2,000


2,000 up to 2,500


Source: Energy



Adjustments must be made for the following circumstances:

  • Reduce capacity by 10 percent for heavily shaded rooms.
  • Increase capacity by 10 percent if room is very sunny.
  • If more than two people regularly occupy a room, add 600 BTU per additional person(s).
  • Increase capacity by 4,000 BTU if unit is used in a kitchen.

Always consider air flow when locating a unit. Direct air flow toward the middle of the room to be cooled.


Appliance Rebate             

Central Electric Cooperative (CEC) offers a $25 rebate for choosing an EnergyStar certified window air conditioner. Before purchasing a unit, visit to assure it is EnergyStar certified.              


Peak Alerts

Please set thermostat 2 to 4 degrees higher on very hot and humid "Peak Alert" days between the hours of noon to 6 p.m. This will help stabilize CEC's rates. Peak Alerts are announced on our website or by listening to Forever Broadcasting stations 98.5 FM, 99.3 FM, and 107.7 FM.


Earn $50 Bill Credit

Let CEC install a load control device on your own electric water heater and earn a $50 one-time bill credit and a monthly $2.50 bill credit. Call 800-521-0570 x2195 to learn more. Members having a water heater installed by the cooperative are not eligible for the credits.


Twitter and Load Control  

Participants in our load control program for electric heat and water heaters can find out when and how long control periods are predicted by logging onto and clicking our Twitter logo. Please remember these are only predictions and actual times may vary.



If you have any ideas for future E-Tip topics, email me at


80th Annual Meeting

This year, CEC celebrates its 80th anniversary at its annual meeting Aug. 25, 2017. Learn more by visiting

Powered by Touchstone Energy Cooperatives Logo
Link to Nothing here. link to the cooperative action network website