1 Peer-reviewed (refereed or scholarly) journals-Articles are written by experts and are reviewed by several other experts in the field before the article is published in the journal in order to insure the article's quality.
One key component to an efficient walk-in cooler is its insulation. A standard walk-in cooler will have between 2 and 4 inches of Styrofoam insulation within its walls and a rubber sealing gasket around its door to help ensure that it is both airtight and well-insulated against the temperature of the air outside.
1 cooler: a refrigerator for cooling liquids.  A cool box, cooler, portable ice chest, chilly bin (in New Zealand), or esky (Australia) most commonly is an insulated box used to keep food or drink cool. Ice cubes are most commonly placed in it to help the things inside stay cool.