Certified Facility Manager (CFM) Practice Exam

How is the energy efficiency ratio (EER) of cooling equipment calculated?

1. By multiplying the cooling achieved and energy used

2. By adding the cooling achieved to the energy used

3. By dividing the cooling achieved by the energy used

4. By finding the average of cooling achieved and energy used

The correct answer is: By dividing the cooling achieved by the energy used

The energy efficiency ratio (EER) is a critical measure used to assess the efficiency of cooling equipment, such as air conditioners and heat pumps. It specifically reflects the ratio of the cooling output, measured in British thermal units (BTUs), to the electrical energy input, typically measured in watt-hours. Calculating EER involves dividing the total cooling output by the total energy consumed during the cooling process. This means that if a cooling unit accomplishes a certain amount of cooling, expressed in BTUs, and uses a certain amount of energy during that operation, the EER could be expressed as BTUs per watt-hour. A higher EER indicates a more efficient unit because it provides more cooling for each unit of energy consumed. The other possible calculations do not accurately reflect the relationship between cooling output and energy use. Multiplying, adding, or averaging the values do not provide a valid efficiency measurement, masking the direct accountability of energy consumption relative to cooling performance. Thus, using division to assess how much cooling is achieved per unit of energy used provides a clear understanding of energy efficiency for cooling equipment.