According to the U.S. Department of Agriculture, there was more than 3.04 billion gross cubic feet of general refrigerated or cold storage capacity in 2001. These facilities are essential for the safe handling and storage of food products and other goods. Without storage areas that provide a consistent environment and sustain its integrity, many products would not be readily available to consumers.
Expanded polystyrene (EPS) insulation board is ideal for use in walls and roofing systems in the construction of cold storage space. These facilities store food, flowers and other temperature sensitive commodities. The temperatures range from normal room temperature 20ºC (68ºF) to cryogenic temperatures -100ºC (-148ºF). As surface temperatures decrease, the quality of construction and sustainability required becomes more critical.
The performance properties of EPS, including constant thermal resistance, dimensional stability, chemical inertness and sustainability, make it well suited for use as insulation. Additionally, its closed-cell structure provides minimal water absorption and low vapor permeance, an important design consideration for damp environments.
Cold storage insulation is normally applied in two layers with joints staggered between layers and boards tightly butted. The EPS boards must be firmly and permanently bonded to the wall, ceiling and roof using adhesives. The first layer of floor insulation is bonded to sub-slab while the second layer is installed dry. Thicker coatings of heavy-bodied adhesives may be used to provide some straightening or bridging on an irregular wall surface. Adhesives are applied to provide 100 percent contact and to fill any voids. Spot or strip applications of adhesives are used only where a vapor or air barrier is installed.
All components of construction must work together to achieve a system that will enclose space and hold it at the desired temperature for extended periods of time without any deterioration. For instance, it is recommended that any lumber incorporated into cold storage construction be pressure treated with a wood preservative.
Ensuring a low temperature, the space must be properly enclosed and equally important, the removal of heat generated from refrigeration equipment and other machinery. There are several methods that can be employed to eliminate heat sources from the space to reduce maintenance problems.
To achieve maximum insulation efficiency and long-term performance, mechanical equipment may be adapted for the cold temperatures. Refrigeration units can be reduced in size and include an automatic defrosting cycle, in order to decrease the amount of heat generated. Other items such as pumps, fans and lights should also operate properly. The thickness and type of insulation in the construction deters the movement of outside weather and normal self-generating building heat.
The use of doors plays a large role in the ability to sustain the appropriate temperature. The frequency of door opening and closing is of greater concern than the size of the door. Operational guidelines should be established to quickly expedite the loading and unloading of product in the cold rooms. Forklift truck operation and other mechanical systems allow quick opening and closing doors with mechanical or remote operators. The investment on doors can result in energy savings by decreasing the amount of heat transfer. Holding areas with a regular door outside of the cold room can also help reduce the flow of warm air into a cold area.
Contractors must be aware of unsealed openings around electrical conduit and equipment hangars, structural cracks and poorly constructed joints at the wall, such as ceiling line, construction joints, etc. Warm air can infiltrate the storage area through these imperfections compromising the environment. When warm, moist air enters a freezer room it can cause a rapid build up of ice, which can force movement of the structure.
Frequently, goods entering the facility have a higher temperature than that of the storage area. Design provisions must be incorporated in the refrigeration unit to remove the newly introduced heat.
In the same respect, any modifications to the design, operation of the building or special care in workmanship which lowers heat gain within the cold room, will reduce the load on the refrigeration equipment which can effect noticeable energy savings. It is critical that the necessary prevention of heat gain can be assured at the design stage to minimize the refrigeration equipment needed.
The construction must be tight so that there is no air movement through the structure from the outside to the inside of the room. The location of air seals and vapor barriers can be cold storage rooms. The movement of water vapor must be restricted by the use of vapor barriers or by the vapor barrier characteristics of EPS rigid foam insulation. The placement of air seals and vapor barriers in the construction is imperative to reduce the possibility of leakage.
Expanded polystyrene insulation meets extensive model building code requirements. More than 48 EPS manufacturers with hundreds of locations in the U.S. and Canada maintain numerous listings at Factory Mutual (FM), Underwriters Laboratory (UL), Underwriters Laboratory of Canada (ULC) and other testing facilities.