The invention concerns a portable cooling system with optimum energy consumption that uses a Peltier cooling module, that has a metallic heat sink on both the warm and cold side and at least one fan on the warm side for better heat transfer, to create a useful cold-store. The system distinguishes through the thermal separation of the cold side of the Peltier cooling module from the actual cold-store and purposeful heat transfer between both rooms with the help of a gaseous or liquid heat transfer medium. This drastically reduces the energy consumption so that it becomes possible to construct a portable, practical cooling system that is suited for example to store medicines, in particular insulin.