When purchasing an air conditioner, you need to make sure that you know all the specifications of the unit you are looking for. As you may not be an expert when it comes to air conditioner specifications, you might want to do a little research when it comes to EER and SEER ratings. EER and SEER ratings will help you to make the right choice of product, size and power. What are EER and SEER ratings? EER or Energy Efficiency Ratio is the ratio of the cooling capacity to the power input. The higher the EER rating, the more efficient the air conditioner. To calculate the EER rating of a unit, you need to use the following formula: output cooling energy (in BTU) and divide it by the input electrical energy (in Wh). SEER or Seasonal Energy Efficiency Ratio is explained by the air conditioning, heating, and refrigeration institute’s performance rating of air conditioning and air source heat pump equipment. Before purchasing an air conditioner, it is recommended that the EER and SEER ratings are correct. To calculate the SEER rating of a unit you need to use the following formula: output cooling energy (in BTU) over a season and divide it by the input electrical energy (in Wh) during the same season. If you are not sure which formula to use and how to use it, an air conditioning specialist will be able to assist you when you want to inquire about the EER and SEER ratings of the air conditioner you want to purchase. What should the ratings be? As SEER ratings are calculated universally, it is hard to say with definite fact what the SEER rating should be as not all parts of the world have the same climate. Thus, SEER ratings will differ from place to place, although the same rating calculation will be used. The higher your SEER rating, the more expensive your air condition unit will be. For an average climate of 83 degrees, your SEER rating will be 14. For a climate that is lower than average, the SEER rating will drop a certain amount. When calculating the EER rating, a consistent outside temperature of 95 degrees, a constant inside temperature of 80 degrees and a humidity level of 50% is used. Knowing that, you can calculate exactly what your EER rating should be, regardless of where you live and what the climate may be. When do I use EER and when do I use SEER? SEER is used when comparing one air conditioning unit to another and is typically used with large central air conditioning units. As SEER is calculated by using a temperature range, it is not the correct rating to use when wanting to know how efficient the unit is or how much money you will save. EER ratings are used when you have a smaller window mounted air conditioner, typically used in your home. With the EER rating you can calculate how efficient the unit is and can compare how long the unit will last as well as how much money you will save by using less power. Apart from the ratings, you need to make sure that the air conditioning unit is installed properly in order to ensure optimum use, efficiency and a longer life span.