How a reefer actually works
Unlike a dry box, a reefer plugs into power — on the vessel, at the terminal, and on a genset for road legs — to run its cooling unit at a commanded set point, anywhere from deep-frozen (around -25°C and below for some cargo) to chilled (0–4°C) to controlled ambient. Standard equipment is the 20' and 40' reefer (ISO types 22R1 and 42R1); the 40' high-cube reefer is the workhorse for most perishable trades. Beyond temperature, many cargoes need controlled ventilation (fresh-air exchange for respiring produce) and humidity management, and high-value pharma often ships as 'controlled room temperature' with tight tolerances.
The cold chain is only as strong as its continuity: a gap in power at a terminal, a delayed plug-in after discharge, or an unnoticed unit alarm can spoil an entire load. Reefers generate continuous temperature and status data, and monitoring it in real time — not discovering a deviation at destination — is the difference between a claim and a delivery.
Why reefer costs more and demands more
Reefer freight carries a premium over dry: the equipment is expensive and limited, it consumes power, it attracts reefer surcharges and monitoring charges, and it needs plug-in slots that constrain vessel and yard capacity. Free time is often tighter and demurrage/detention more punishing, because a reefer sitting unplugged is both a cost and a spoilage risk. Some trades also require pre-trip inspection (PTI) of the unit before loading and specific documentation for perishables or pharma.
For a forwarder, reefer is higher-margin but higher-responsibility cargo: quoting must capture the set point, ventilation, and any cold-chain compliance up front, and operations must treat power continuity and temperature monitoring as first-class milestones, not afterthoughts. It is exactly the kind of shipment where getting the requirements structured correctly at quote time prevents an expensive failure later.