ENERGY EFFICIENCY RATIO, COEFFICIENT OF

PERFORMANCE & SEASONAL ENERGY

EFFICIENCY RATIO

 

The Energy Efficiency Ratio (EER) is the ratio of output cooling in Btu/h to energy input in watts. It is at a given single outside temperature.

EER = cooling in (BTU /h)/ energy input in watts

Calculate EER  at 95⁰F outside temperature. The return air temperature is 80⁰F and 50% relative humidity.

COEFFICENT OF PERFORMANCE, COP

Calculate COP under a set of inside and outside design conditions. There are summer and winter outside design conditions. Cop is ratio of cooling effect to energy input in summer. In winter, COP is the ratio of heating effect/energy input. COP refers to year round air conditioning.

COP = N/W

N is the cooling effect say in watts

W = work input in watts

RELATION BETWEEN CO AND  EER 

EER = COP * 3.412

The EER is related to the coefficient of performance. The primary difference is that the COP of a cooling device has no units i.e. uses same units of the cooling load and the electrical power input. Therefore  COP is same in any system of units. Values of EER will be different in different units.

 EER = COP * 3.412

Seasonal Energy Efficiency Ratio (SEER)

It is an international standard for energy efficient consumer products. It started in USA in 1990. Later other countries adopted it. SEER is the energy star logo. Devices carrying the Energy Star logo (SEER) generally use 20%–30% less energy.

SEER = cooling output( in BTU/h)/work input in watts 

The higher SEER rating means more energy efficient.

The units of Seasonal Energy Efficiency Ratio (SEER) and EER are same. SEER represents the expected overall performance for a typical year’s weather in a given location. The SEER is thus calculated with the same indoor temperature, but over a range of outside temperatures from 65 to 104 ⁰ F. It is over 8 hours interval & outside temperatures varying with  5^oF. It indicates how different outside temperatures affect EER.

EER for residential central cooling units = 0.875 × SEER.

SEER is a higher value than EER for the same equipment.

RELATION BETWEEN EER AND SEER

 EER for residential central cooling units = 0.875 × SEER

SEER has a higher value than EER for the same equipment.

In a nut shell

EER=0.875 x SEER

EER = COP x 3.412