(extracted from IBPGR 1976)
Deep-freeze chests operating at approximately -20°C, such as those used domestically, are entirely suitable for the long-term conservation of seeds. Such chests have the advantages that they are often immediately obtainable locally, and that their number could be added to as a collection increased in size.
It has been suggested that a large seed collection could also be housed in this way. However, in terms of capital and running costs per unit volume of storage space, deep-freeze chests compare unfavourably with the smallest and most expensive cold room (85 m3) considered in this report which provides storage space at a cost of $314/m3 (including warning and safety devices). A typical chest, internal volume 0.3 m3 (13.5 ft3), would cost about $350 in Europe and provide storage space at a cost of $947/m3 (excluding warning and safety devices). In other words, on this basis deep-freeze chests are likely to cost about three times as much as cold rooms 1).
Deep-freeze chests would be suitable for very small collections of seeds, particularly if at least one spare chest and a small standby generator were included in the facility. They could also be used as a temporary expedient while a major facility is being constructed. However, they would not seem to provide a suitable alternative to a large cold room for the long-term storage of major seed collections.
1) Costs quoted in this paragraph were those applicable in 1976.