Energy Efficiency Ratings
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The energy efficiency rating is used to measure efficiency of an energy system or a device. This rating is used to indicate the energy requirement of an appliance to carry out a certain task. The energy efficiency rating of an appliance is low if it uses more energy to perform a task compared to other appliances of similar type.
The energy efficiency rating is used to measure efficiency of an energy system or a device. This rating is used to indicate the energy requirement of an appliance to carry out a certain task. The energy efficiency rating of an appliance is low if it uses more energy to perform a task compared to other appliances of similar type.
Energy Efficiency Ratings at a Glance
Different energy efficiency ratings have been devised to measure the efficiency of industrial and household appliances. SEER and EER are the two energy efficiency ratings that are mostly used for central cooling systems.
SEER stands for Seasonal Energy Efficiency Rating. It is used to rate the energy efficiency of the residential central air conditioners. The value of SEER is derived by dividing the cooling output with the units of power consumption. The unit of SEER is Btus per hour. The following example will clarify the point.
If a residential air conditioner uses 700 watts of electricity to generate 5,000 Btu of cooling and another air conditioner uses 500 watts of electrical energy to provide same units of cooling, then the second air conditioner is considered to be more efficient as per the SEER system.
The EER or Energy Efficiency Ratio measures efficiency of a cooling system when the outdoor temperature remains at 95? Fahrenheit. High Energy Efficiency Ratio indicates that the cooling system is highly efficient. The ratio is expressed by the following formula:
Energy Efficiency Ratio = Btu per hour of cooling at 95? F / Watts consumed at 95? F
If a cooling system uses 1500 watts of electrical energy to generate 12,000 Btu/hour of cooling, the Energy Efficiency Ratio is 8. The EER for another cooling system, which requires 1200 watts of electricity to generate same amount of cooling happens to be 10. As per the EER rating, the second cooling system is more energy efficient, given the outdoor temperature is 95? F.
Coefficient of Performance or COP is used to measure the energy efficiency of chiller or heat pump. Higher COP value improves the rating of an appliance in the energy efficiency scale. COP is calculated by the following formula:
COP= BTU of heat generated at 47? F / BTU worth of electric power used at 47? F
Among the other energy efficiency ratings, Heating Seasonal Performance Factor or HSPF and Annual Fuel Utilization Efficiency or AFUE are worth mentioning.
