Indian Seasonal Energy Efficiency Ratio

Bureau of Energy Efficiency (BEE) with the objective of progressively improving the efficiency of Room Air Conditioners (AC) and transforming market towards better energy efficiency standards has brought in Star labelling of ACs.

Since 2010, BEE has mandated air conditioners as a mandatory-labelled appliance under Energy Conservation Act and since then air conditioners cannot be sold without star label. BEE continuously tightens the standards such that, the Star-5 in 2010 became Star-3 in 2015 and will become Star-1 in 2018 as per new ISEER methodology. The weighted average Energy Efficiency Ratio (EER) of AC has increased from 2.6 in 2006 to 3.26 in 2015, which is an increase of 25% in efficiency due to tightening of standards. Now as per latest notification, from January 2016, Star-2 is the least efficiency level to be sold in the market, hence variation in power consumption is compared between Star-5 (most efficient) and Star-2 (least efficient) air conditioners.

What is ISEER

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.

Note: National weather data based on the weather profile for 54 cities across India. Source – The Indian Weather Data Handbook, 2014

Star rating parameters for ISEER

The star rating parameters for ISEER is as follows.

What should consumers look for

Consumers should look for the Star rating label, a sample of which is given below. Consumers can now purchase air conditioners with higher efficiency leading to lower electricity bills. Ratings based on ISEER have been introduced on a voluntary basis for Variable Speed (Inverter) Air Conditioners since June 2015 and proposed to be merged with fixed speed air conditioners in the mandatory regime from January 2018.

Source : Schedule for energy labelling of variable capacity air conditioners