Getting to Know Your Air Conditioning System: Part 3: BTU and EER
If you’ve done any research into getting a new HVAC system, you’ve seen the term Btu to describe air conditioner capacity. According to Wikipedia, British thermal units (Btu) is the approximate amount of heat necessary to raise the temperature of one pound of water from 39 degrees to 40 degrees Fahrenheit. In heating and cooling terms, one ton equals 12,000 Btu.
A typical 12,000 square foot house may require a five ton, or 60,000 Btu, air conditioning system.
The energy efficiency rating (EER) of an air conditioner is determined by putting its Btu rating over its wattage.
A higher EER is obviously desired, but may also be more expensive. In order to determine the best option for you, consider how many hours per year the air conditioner will run and how much a kilowatt-hour (kWh) costs in your area.