Traction energy and body-cooling energy behave differently on a refrigerated trip. First record how the unit is supplied: direct drive from the vehicle engine, an independent diesel unit, separate electric standby or battery supply. For a North American road application, the Thermo King V-800 series describes a vehicle-engine-driven road compressor and separately powered electric standby; this example does not mean every unit has the same measurement boundary.
Fuel stock balance
For a separate unit tank or traceable fuel record, use one period boundary: opening stock + fills - closing stock = fuel used. Read the balance on the assumption that the example has no unrecorded transfer or loss and that stock values share one period and unit; the difference is not automatically burned fuel. As a hypothetical example, 40 L + 60 L - 25 L = 75 L.
Direct-drive separation. When the compressor is driven by the vehicle engine, it may have no separate fuel tank. Matched records from similar route, load, ambient and operating-mode conditions can estimate a refrigeration share; the full difference between two trips is not automatically refrigeration. Engine hours are not compressor runtime. Compare litres per hour only against the same defined mode hours.
Electric standby and battery
For a separate electric standby compressor or battery supply, keep a meter and kWh record instead of a fuel figure. kW is instantaneous power and kWh is period energy; do not place them in the same column. Define the boundary between total vehicle energy and the refrigeration allocation before reporting. Do not count the same consumption once in total vehicle fuel and again in the unit line.
| Configuration | Primary record | Matched condition |
|---|---|---|
| Direct drive | Matched route and mode hours | Same load, ambient, setpoint and door profile |
| Independent diesel unit | Tank stock, fills and closing stock | Same period and transfer record |
| Electric standby | Meter kWh, connection and duration | Same waiting and supply conditions |
| Battery supply | Battery energy and charging kWh | Charging and use periods separate |
Close periods with the same units and boundaries. A matched direct-drive route gives an estimate, not an exact difference; temperature, door openings, insulation, traffic and load can confound it. An independent diesel tank can be more direct, but unrecorded transfers still leave the balance incomplete.
A passive option may reduce vehicle-unit fuel, but plate-freezing energy, preparation time, container return and depot electricity appear in separate lines. Do not add that energy to total vehicle energy and then write it again as unit fuel. The net result comes from measuring the whole cycle under the same route and product conditions.
Refrigerant replenishment is not fuel consumption. A refill record does not automatically show leak quantity, emissions or a specific factor. Refrigerant quantity and emissions are handled with the appropriate maintenance and reporting method and kept separate from the fuel line.
End the report with total fuel drawn from the vehicle tank as the main line; show the estimated direct-drive refrigeration share as a nested allocation within that total, not as an additional sum. Keep independent-unit diesel, electricity kWh and passive preparation energy under separate boundaries. Use the refrigerated vehicle cost guide and state opening and closing stock, fills, operating mode, hour definition and measurement boundary.
