How annual energy consumption of Refrigerator is calculated for Star rating ? -

Refrigerators comes under mandatory scheme for star labeling, and therefore any refrigerator being sold in india must have star rating. Star rating helps buyer to take informed decision on purchase of refrigerator. Annual energy consumption of refrigerator is the basis of star rating, higher star rating indicates high efficiency machine and it will consume less power while operation.

As the BEE refrigerators are classified in two categories.

Classification of Refrigerator :-

Direct cool refrigerators.
Frost free refrigerators.

Lets understand both type of refrigerators, In direct cool refrigerators cooling is done by natural convection and not with the use of internal forced circulation fans, However some direct cool refrigerators may have internal circulation fans for avoiding internal condensation but not claimed as frost free by manufacturer. While in frost free refrigerators cooling is provided by forced air circulation, The system is automatically operated to prevent permanent formation of frost on all
refrigerated surfaces and no accumulation of ice or frost forms on stored food

Projected Annual Energy Consumption (PAEC)

For rating of any refrigeration system PAEC is the measurement criteria, PAEC is further used to award rating to the refrigerator. PAEC is the estimated energy consumed by the refrigerator for complete one year of operation. Test conditions for both type of refrigerators are defined to have uniformity across manufacturers.

PAEC is calculated by

PAEC = Et * (365/1000) (kWh/Year)

Et = tested energy consumption expressed in Wh per 24 hours, rounded to the nearest whole number.

Qualification Criteria

Pull down test is done for qualifying refrigerator to be tested for star rating or PAEC, In pull down test refrigerator is testing for reaching its cooling levels form predefined conditions as below :

(a) Room ambient temperature shall consider 43 ± 0.5 º C for both direct and frost free refrigerator.
(b) The direct cool refrigerator inside Target Temperature for Freezer Compartment is considered as -8 ºC while for frost free refrigerator Freezer compartment is -18 Deg C, Fresh food Compartment +5 Deg C, Celler compartment 8 to 14 Deg C, Chill compartment 3 Deg C.
(c) Temperature sensors location in the freezer compartment shall comply with clause 7.5 of IS 15750:2006.

The pull down time and percentage running time as measured shall not be above the value stated
by the manufacturer by more than 5 percent of the latter.

Tested Energy Consumption (Et)

Energy consumption of refrigerator is tested for 24 Hrs of operation during which average temperature of freezer and refrigerant compartment is exactly equal to target temperature. Ambient temperature during test is 32Deg C with No load in refrigerator and predefined temperature as per IS1476-1 for direct cool refrigerator and IS15750 for frost free refrigerator.

After getting Et , PAEC is estimated.

Comparative Energy Consumption ( CEC):

The CEC for a model shall not be less than the average (rounded to a whole integer) PAEC value (i.e. PAECav) for the three (or more) units which are tested to determine the label particulars. The CEC shall be an integer in units of kWh/Year.

Comparative Energy Consumption (CEC) = knf * Vadj_tot_nf + cnf

Where,
Knf = Constant multiplier (kWh/Litre/Year)
Vadj_tot_nf = Total adjusted storage volume for household Frost Free Refrigerator(Litre)
Cnf = Constant fixed allowance (kWh/Year)

Total Adjustment Volume

The rated storage volume of a compartment adjusted to compensate for heat loadings on spaces which are at temperature other than that of fresh food type space. The adjusted volume is calculated on the basis of the STORAGE VOLUME of
each compartment.

TOTAL ADJUSTED STORAGE VOLUME FOR Direct Cool

Fresh Food Compartment Target Temperature = +3 Degree Celsius
Freezer Compartment Target Temperature = – 6 Degree Celsius
Adjusted Volume Factor = (Test room Temperature – Freezer Temperature) / (Test room Temperature – Fresh Food Temperature) = [32 – (-6)] / [(32 – 3)]= 1.31
Total Adjusted Volume for Direct Cool refrigerator (Vadj_tot_dc) = Fresh Food Storage Volume + 1.31 * Freezer Storage Volume

TOTAL ADJUSTED STORAGE VOLUME FOR NO FROST (Vadj_tot_nf )
Fresh Food Chamber Target Temperature = +3 Degree Celsius
Freezer Chamber Target Temperature = -15 Degree Celsius
Adjusted Volume Factor = (Test room Temperature – Freezer Temperature) /
(Test rom Temperature – Fresh Food Temperature)
= [32 – ( -15)] / [(32 – 3)] = 1.62
Total Adjusted Volume for No Frost refrigerator (Vadj_tot_nf) = Fresh Food Storage Volume + 1.62 * Freezer Storage Volume

Star Rating

The CEC and Total Adjusted Storage Volume is be used to estimate annual energy consumption of refrigerator thus defining band for Star Rating. Star rating band is fixed for specific period and based on technology advancement, Star rating targets are

For direct cool refrigerator: