4.4 Walls, materials, heat transfer, and permeability to moisture

The most effective way of controlling environmental conditions is to build a room with good thermal insulation and constructed with materials that are reasonably impermeable to the transfer of airborne moisture. Standard building materials such as stud plaster walls, bricks, and cinder blocks do not provide very effective insulation against temperature change and allow high levels of moisture to pass into the storage environment. If these materials are used, sealants must be applied to all surfaces, and all gaps, including around doors, must be sealed. The use of airlocks at doorways should also be considered.

One good way to provide a temperature controlled storage environment is to build an insulated envelope or structure within an existing building (4.2). The walls of such an envelope can be made from highly impermeable materials such as rigid aluminium and polystyrene sandwich panels as used to build food storage areas. All entry spaces including doors, electrical and other ducts, screw holes and fixing components must be sealed, as effective vapour sealing of the rooms is vital to their performance. Most places that use this type of building technology report being able to significantly reduce the size and cost of air conditioning plant. In the event of a disastrous loss of power, such storage environments maintain their conditions for a longer period of time.