Freezing Technology

6.1.4 General layout

A single-storey building can either have one single room or it can be divided into a number of rooms. Normally all the rooms are operated at the same temperature, for fish preferably in the range of –24^o to -30^oC. Most stores are built at a higher level than the surrounding yard with a special loading ramp at one or more sides. The loading ramp level corresponds to the height of the most commonly used vehicles.

The engine room should be as close as possible to the position of the air cooling equipment within the store.

Modern large or medium cold stores are built as one-storey buildings designed for mechanical handling, e.g., forklift trucks and automatic stacker cranes. Manual handling is, however, still used for most small-sized stores.

A cold store can be built as an ordinary building using conventional building material, such as bricks, concrete or concrete precast sections to which a vapour barrier and insulation is fitted internally. Modern insulation material, in particular polyurethane, has a strength that can be utilized structurally. Today, this is used for panel designs suitable for all sizes of cold rooms from 20m³ to 250 000m³. Factory made insulation panels are delivered to the site complete with a vapour barrier and internal cladding, thus reducing the site work to a minimum. There are two basic principles for panel-built cold stores. A common system has an external structure and cladding with wall insulation inside of the columns and the insulated ceiling hanging from the outer roof structure.

The panels normally used in these systems are either polyurethane or polystyrene insulated panels with or without frames. They are manufactured as sandwich panels, one face being the vapour barrier of light-gauge galvanized steel sheet and the other face being the internal finish of plastic-coated galvanized sheet or aluminum sheet. A decorative external cladding is erected on the outside of the columns. The roof insulation is constructed as a suspended ceiling. The roof panels are, in principle, the same as the wall panels, but are sometimes equipped with wooden frames.

The latest development are panels with a rib profile on the external face of aluminum –  with polyurethane foam insulation and an internal face of low profile corrugated aluminum. The space between the panels is filled with one component polyurethane foam. The internal cladding is sealed with a PVC strip. One component foam is also used to join wall panels to roof panels and seal around doors, etc, maintaining good insulation properties throughout the building. With this design both the insulation and external vapour barrier are entirely sealed units enveloping the whole building. This means that losses via heat bridges or air leakage are completely eliminated, which gives practical insulation properties closer to theoretical values than normally expected.