If a blackout looms, packing a refrigerator and freezer with water jugs and other thermal mass can help save food from spoiling. Transferring high-demand items, such as milk and eggs, to coolers can also reduce the how often the refrigerator must be opened, further extending the life of its contents.
If there is advance notice of a blackout, such as a looming weather system, taking the right steps early on can make a huge difference. The air inside a refrigerator and freezer warms first, so filling up empty space helps keep temperatures low. Water jugs are the easiest and simplest method of adding thermal mass to the refrigerator, and frozen jugs can be cycled into the main refrigerator compartment for even more cooling power.
In a blackout, a refrigerator should keep foods cold for at least four hours, and a freezer keeps food safe for 24 hours if half filled or 48 hours if completely full. When the doors are opened, though, warm air rushes in to reduce those safe periods. Keeping the most-used foods easy to find reduces the amount of time the door stays open and the chill can escape.
A pair of thermometers is a great way to tell whether the refrigerator and freezer remain safe once the power returns. If perishable food warms above 40 degrees Fahrenheit for more than two hours, it is potentially dangerous to consume.