How to Determine What Size Central Air Conditioner for a Home

Bigger isn't always better when it comes to the right size for your air conditioner.

Central air conditioning is designed to cool several rooms at once, rather than just one room like a window-unit air conditioner. In order to get the most efficiency from a new central air conditioning system, you need to size the system according to the square footage and energy efficiency of your home. In sizing your central air conditioner, keep in mind that the largest systems are not necessarily the best systems depending on how your home is constructed.

Instructions

1. Measure the length and width of each room, closet and hallway in your home.

2. Multiply the length and width for each room, hallway or closet to get the square footage for each area.

3. Add the square footage for all the rooms, hallways and closets in your home. This is the total square footage of your property that needs to be cooled.

4. Look at a British thermal unit (BTU) chart. A BTU is a unit of measurement equal to the amount of energy needed to raise 1 lb. of water 1 degree; it is a measurement of heat. Using the figure you calculated for your home's total square footage, find the average BTUs recommended for a home with your square footage on the chart.

5. Add 4,000 BTUs for every room that isn't properly insulated or contains a kitchen. Improper insulation lets more heat into your home, usually through the roof. Cooking also produces heat.

6. Figure out how many windows in your home get sun regularly. Add 1,500 BTUs for each of these windows. Add 1,500 BTUs for every room over a kitchen that's in use during the daytime, as well. Your air conditioning system will have to work harder to negate solar and cooking heat.

7. Count how many people are in your home. For every person over two, add 600 BTUs. Every person gives off some degree of heat energy as a result of physiological processes, so the more people you have in the house, the harder your central air will have to work to keep the rooms cool.

8. Look at how your home is shaded. Take off 1,000 BTUs for any room that is on the shaded side of your property.

9. Double-check your calculations and look at the total BTUs you calculated. This total is the amount of BTUs your new central air conditioning system should be able to handle. Try not to buy a system that handles a BTU amount that is significantly less or higher than the total you've calculated.

References

• Inspectapedia: How to Choose an Air Conditioner - BTU Chart

Resources

• Read this Article in Spanish