|Ventilated containers, i.e. passively ventilated containers (coffee containers), constitute an attempt to exchange hot air full of water vapor, which arises during the day, and thus to cool down cargoes coming from the tropics and to remove the water vapor they give off. Since the temperature of the cargo is higher than the temperature of the air surrounding the container, the necessary circulation of heat is maintained and moisture and heat are thereby transported out of the container (see also Section 10.3.7).
When this passively ventilated container is used to transport a cold cargo in winter from temperate latitudes into the tropics, this ventilation is ineffective, since the air flow would have to be reversed, with the hot external air having to flow downwards through the container as the cargo cooled (risk of sweat). This happens only to a limited degree, so meaning that the air exchange has to be caused by air circulation outside the container. This occurs more intensively on deck, due to the relatively high level of air circulation around the container, than in the hold, where the only air flow available is that generated by the ventilation system.