How should passive and active cooling energy use be compared?

A passive system runs no unit on the vehicle, yet it is not energy-free: plates are frozen at the depot and boxes are washed and returned. The comparison is made on the same delivery service.

6 August 2026Updated 28 September 2026

Short answer

First tie both systems to the same service: same product, quantity, route, ambient temperature and acceptance condition. For passive, measure plate freezing, washing and return; for active, vehicle refrigeration, pre-cooling and extra vehicle movements. The result is per delivery produced by depot and vehicle together, not from one equipment rating.

A passive system is not energy-free just because no unit runs on the vehicle. GEBHARDT eutectic plates are frozen at the depot: for a plate melting at -3 °C the recommended freezing is 24 h at -8 °C, with the time ranging from 8 to 24 h depending on the refrigeration technology. The freezing temperature must be at least 5 °C below the plate's melting point.

Item	Passive	Active
At the depot	Plate freezing, washing	Vehicle pre-cooling
On the road	No unit	Unit fuel or electricity
Return	Empty box and plate flow	Extra vehicle movement

Mixed transport is modelled as a separate scenario. Writing down the system boundary and the comparison unit first is also the opening step of the ISO 14040 life-cycle framework.