Energy Conservation in Cold Storage and Cooling Operations
Energy use in a cold storage facility is affected by the amount of heat the refrigeration equipment must remove and the efficiency of the equipment. The main sources of heat in a facility for long-term storage are transmission through walls, evaporator coil fans, lights, air leakage, and respiration of the stored commodity.
Heat entering a cold storage facility through walls can be minimized by increasing the insulation and by painting the exterior a light color. Doubling the insulation (as measured by R value) reduces transmitted heat by half. Newer facilities use insulation levels as high as R40 in walls and R60 in ceilings. In general, it is advisable to build with more insulation than utility costs may presently warrant, because energy costs are difficult to predict and it is much cheaper to install insulation during construction than after construction is completed.
Sun shining on walls and roof dramatically increases the effective outside temperature, increasing heat flow into a storage facility. A dark, flat roof can be 75°F (42°C) warmer than the outside air temperature. Painting a south-facing wall a light color can reduce the effective wall temperature by 20°F (11°C) compared with a dark wall. Walls and roof of a cold storage facility should be painted a light color or shaded from the direct sun.