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Choose an air conditioner that is properly sized

By Recyclebank |
An air conditioner is more effective at removing heat and humidity when it is the proper size for your space.
Choosing an air conditioner that is properly sized for your space will increase its efficiency and cool more effectively.

How to choose a central air conditioner that is properly sized

The size of your central air conditioner depends not only on the size of the space you want to cool, but also on the following factors:

  • How many windows there are in your house
  • How much shade cover your home receives and where
  • How well your home is insulated
  • How much heat is generated by your appliances and the occupants of your house
A reputable air conditioning contractor will use a calculation procedure to size your system. The calculation procedure is published by two groups: the Air Conditioning Contractors of America (ACCA) and the American Society of Heating, Refrigerating, and Air Conditioning Engineers (ASHRAE).[1] Visit their websites to locate a member contractor near you.

How to choose a room air conditioner that is properly sized

If a room air conditioner is too small or too large, it will not cool as effectively. Installing a big unit with a larger Btu than necessary will cause it to cycle off too quickly without removing humidity from the air. Likewise, an air conditioner with a smaller Btu than needed will run continuously, wasting energy while not cooling efficiently. Installing a unit that fits your room size is the most efficient and effective way to dehumidify the air.

ENERGY STAR provides an excellent step-by-step description of how to calculate your room A/C needs. There are extra tips at the end to accommodate for sun, shade, appliances, and occupants.

Choosing an air conditioner that is properly sized helps you go green because…

  • It increases the efficiency of your cooling system, thereby saving energy and preventing greenhouse gas emissions.
Americans make up just 5 percent of the world's population, but use 26 percent of the total energy consumed on the planet. Ninety percent of residential energy consumed in America is due to household appliances, such as heating and cooling systems,[2] which can make up as much as half of a household energy bill.[3] Energy production and consumption increase CO2 concentrations in the atmosphere, contributing to the greenhouse effect, global warming, and climate change.

The choice between a central cooling system and a window unit should be based on a household's necessities and preferences. A window unit is less expensive to operate for cooling a single room, but is typically less efficient than central A/C for cooling the whole house.[1] A central cooling system may be more appropriate if many rooms in the house are used often.[4]


  • Btu (British Thermal Unit) A unit of energy used universally in the heating and cooling industries. It is defined as the unit of heat required to raise 1 pound of water by 1° F.

External links


  1. City of Stockton - Energy Efficiency: Residential Air Conditioning
  2. Solar Energy International - Energy Facts
  3. ENERGY STAR - Heat & Cool Efficiently
  4. Missouri Department of Natural Resources - Residential Energy Efficiency
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