DoE requires all manufacturers to calculate the energy requirements. They have very specific rules. I would think they are required use the results in their documentation if sold in the US. Other countries and EU have similar
They first specify what measurements and how to do the measurements.
For example this is the formula for the Variable Defrost Control< br>
Once the measurement are done then the energy is calculated
6.2 Average Per-Cycle Energy Consumption. The average per-cycle energy consumption for a cycle type, E, is expressed in kilowatt-hours per cycle to the nearest one hundredth (0.01) kilowatt-hour and shall be calculated according to the sections below.
6.2.1 All-Refrigerator Models. The average per-cycle energy consumption shall depend upon the temperature attainable in the fresh food compartment as shown below.
6.2.2 Refrigerators and Refrigerator-Freezers. The average per-cycle energy consumption shall be defined in one of the following ways as applicable.
18.104.22.168 If the fresh food compartment temperature is at or below 39 °F (3.9 °C) during both tests and the freezer compartment temperature is at or below 15°F (-9.4 °C) during both tests of a refrigerator or at or below 0°F (-17.8 °C) during both tests of a refrigerator-freezer, the average per-cycle energy consumption shall be:
E = ET1 + IET
ET is defined in 5.2.1;
IET, expressed in kilowatt-hours per cycle, equals 0 (zero) for products without an automatic icemaker, and equals 0.23 for products with an automatic icemaker; and
The number 1 indicates the test period during which the highest freezer compartment temperature was measured.
22.214.171.124 If the conditions of 126.96.36.199 do not exist, the average per-cycle energy consumption shall be defined by the higher of the two values calculated by the following two formulas:
E = ET1 + ((ET2 - ET1) × (39.0 - TR1)/(TR2 - TR1)) + IET
E = ET1 + ((ET2 - ET1) × (k - TF1)/(TF2 - TF1)) + IET
ET is defined in 5.2.1;
IET is defined in 188.8.131.52;
TR and the numbers 1 and 2 are defined in 184.108.40.206;
TF = freezer compartment temperature determined according to 5.1.4 in degrees F; 39.0 is the standardized temperature for fresh food compartments in degrees F; and
k is a constant 15.0 for refrigerators or 0.0 for refrigerator-freezers, each being standardized freezer compartment temperatures in degrees F.
220.127.116.11 Optional Test for Models with Two Compartments and User Operable Controls. If the procedure of section 3.3 of this appendix is used for setting temperature controls, the average per-cycle energy consumption shall be defined as follows:
E = E x + IET
E is defined in 18.104.22.168;
IET is defined in 22.214.171.124; and
E x is defined and calculated as described in AS/NZS 44474.1:2007 (incorporated by reference; see §?430.3) appendix M, section M4(a). The target temperatures t xA and t xB defined in section M4(a)(i) of AS/NZS 44474.1:2007 shall be the standardized temperatures defined in section 3.2 of this appendix.