How Long Will the Freezer Stay Cold After a Power Outage?
I find thinking about worst-case scenarios is often counterproductive, but I was also a Boy Scout, and the motto “Be Ready” is an indelible part of my psyche. One of the best ways to “be prepared” for any emergency is to keep extra food in the freezer. Freezers require electricity, however, and if you lose electricity the food will eventually thaw. This is why it’s worth knowing how long you can expect the freezer to stay cold if you lose power for extended periods of time.
Fortunately, Matthias Wandel, an engineer and professional carpenter from Canada, did the hard work for us.
After purchasing a new 14 cubic foot freezer, Wandel was curious how long food would stay frozen in the appliance after a power outage. So he installed a TP-LINK HS110 smart plug to keep track of how much power the freezer consumes when plugged in to maintain normal temperatures, and a Raspberry Pi mini PC equipped with temperature sensors to track the internal coldness of the freezer when it was unplugged. …
Wandel ran several experiments with different amounts of food in the freezer for each one. He also ran separate tests to see how much cold was lost when the freezer door was opened when it was empty versus when it was full (you can download all of the data from Wandel’s website) .
How to keep your freezer cold for as long as possible after a power outage
Wandel’s data show that, on average, a full-length upright freezer runs 18 to 36 hours after a power outage until the freezer stops cooling. Thus, most people have about one day left before everything in the freezer thaws.
The exact time will obviously be different for everyone, but there are ways to maximize the volume and location of the freezer so that the food stays frozen for as long as possible:
(Note: These numbers apply to full-length upright freezers. Wandel notes that chest freezers stay cooler and more efficient even after opening because cold air cannot “escape”.)
- Don’t open the door, but if you do, hurry up. Every five seconds, an open door will shorten the total defrosting time by about 7-14 minutes, depending on how much food is being stored.
- The amount of food in the freezer will affect how long it stays frozen. According to Wandel, a tightly packed freezer stays cold for almost twice as long as a freezer with less food and more open space.
- The type of food also affects the thawing time; small items without much water thaw faster, while larger items or foods with more water thaw slower and help maintain the internal temperature. Choose large items with a high water content such as frozen meats, fruits, vegetables, and even ice packs or blocks if there is a lot of extra space.
- The room temperature will slightly affect the defrosting time, so keep the freezer in a cool place if possible. In a warm room, the thawing time can be accelerated by about 25%.
[ Wood Gears ]