The Full Form of ISEER is Indian Seasonal Energy Efficiency Ratio.

Indian Seasonal Energy Efficiency Ratio (ISEER) is an evolved rating methodology for air conditioners that factors in variance in higher temperature in India and rates air conditioners accordingly.  ISEER measures energy efficiency of air conditioners based on a weighted average of the performance at outside temperatures between 24 and 43 degree C based on Indian weather data.

As per Indian Weather Data Handbook, 2014, weather profile of 54 major cities shows that 65% of the total number of hours in a year have a temperature above 24 deg C (5778 hours out of 8760). Air conditioners in India have hitherto been tested under the IS 1391 at a standard operating conditions of outside temperature of 35 degree C. Star rating is given to manufacturers based on the test results provided by them as tested on the above standard.

How is ISEER calculated

ISEER is the ratio of the total annual amount of heat that the equipment can remove from the indoor air when operated for cooling in active mode to the total annual amount of energy consumed by the equipment during the same period.

The method of evaluation of ISEER is based on bin hours of national climatic zone, bin temperature range of 24 – 43°C and 1600 operating hours for cooling per annum.  Table 1 displays bin hours against each bin temperature.