How are portable air conditioners rated?
When it comes to efficiency, portable air conditioners are rated by EER (Energy Efficiency Rating) which is calculated by dividing the BTU by the wattage. When choosing an air conditioner, the more expensive unit with the higher EER rating is the better choice. For example, compare two air conditioners with the EER of 8.3 and 10. Assume you plan to use your air conditioner for about five months out of the year, for 8 hours a day. Also assume that the cost of kilowatt-per-hour is $0.10. The difference in usage is 200 watts, therefore every five hours, the less expensive unit, with 8.3 EER, will consume 1 extra kWh and cost you $0.10 more than the more expensive, unit with 10 EER.
