Method of manufacturing low-temperature storage, and low-temperature storage

A method of manufacturing a low-temperature storage comprising:

• an insulating box article constituted by placing a foamed insulating material between an outer box and an inner box each having its top opened;
• a storage chamber having its top opened provided in the inside of the inner box;
• an insulating door attached to the top of the insulating box article via packing member so as to be rotatable centering on one end;
• a lid constituted of an insulating material disposed so as to open or close an opening in the top of the storage chamber;
• a refrigerant circuit constituted by successively annularly connecting a compressor, a condenser, a heat exchanger, a pressure reducing unit and an evaporator, the compressor and condenser are arranged in a mechanical chamber constituted in a lower part of the insulating box article, the evaporator is heat exchangeably attached to the peripheral surface of the inner box on the side of the foamed insulating material, the refrigerant circuit is filled with a non-azeotropic mixture refrigerant of R245fa, R600, R23 and R14;
• and
• a vacuum insulating panel disposed on the surface of the outer box on the side of the foamed insulating material,
• wherein a thickness dimension of the foamed insulating material between the inner box and the vacuum insulating panel is set so that a temperature of the surface of the vacuum insulating panel on the side of the inner box is not less than a predetermined temperature.