# Is my freezer more efficient when full? **URL:** \ **Category:** Factual Questions\ **Created:** [November 15, 2011, 8:28pm UTC](https://boards.straightdope.com/t/is-my-freezer-more-efficient-when-full/603049 "2011-11-15T20:28:26Z")\ **Posts on this page:** 18\ **Page:** 1
**Author:** ![Dahu](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dahu/32/3416_2.png) [@Dahu](https://boards.straightdope.com/u/Dahu)\ **Post date:** [November 15, 2011, 8:28pm UTC](https://boards.straightdope.com/t/is-my-freezer-more-efficient-when-full/603049/1 "2011-11-15T20:28:26Z")
I read somewhere that empty freezers should be avoided. Mine is quite large, but quite empty. Should I fill it with ice trays and water bottles? ---
**Author:** ![sachertorte](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/sachertorte/32/3727_2.png) [@sachertorte](https://boards.straightdope.com/u/sachertorte)\ **Post date:** [November 15, 2011, 8:48pm UTC](https://boards.straightdope.com/t/is-my-freezer-more-efficient-when-full/603049/2 "2011-11-15T20:48:50Z")
It depends. Full freezers are less prone to take in warm air when you open the door as there is less air to displace. However, if you fill it with ice trays and water bottles, then you will expend energy to freeze those items – possibly more energy than cooling the bit of air that gets in when you open the door. Over a long period of time, small savings from having less warm air get into your freezer when you open the door would add up, BUT if you take out the water bottles and just chuck 'em “too soon” then you will have wasted the savings and then some. In other words, putting in bottles of water that you don’t intend to use would be a waste. My advice would be to leave things be and simply be quick about getting stuff into and out of your freezer. ETA: You could also fill it with something that has a LOW thermal capacity (think syrofoam, NOT WATER!!!) ---
**Author:** ![Swords\_to\_Plowshares](https://avatars.discourse-cdn.com/v4/letter/s/b38774/32.png) [@Swords\_to\_Plowshares](https://boards.straightdope.com/u/Swords_to_Plowshares)\ **Post date:** [November 15, 2011, 8:57pm UTC](https://boards.straightdope.com/t/is-my-freezer-more-efficient-when-full/603049/3 "2011-11-15T20:57:54Z")
It is important that you have some airflow through the freezer, especially if you have an on-door icemaker. With my parent’s Kenmore fridge, the ice maker would freeze up and jam if the airflow was blocked in certain places in the freezer (there had to be some empty space on each shelf). ---
**Author:** ![YamatoTwinkie](https://avatars.discourse-cdn.com/v4/letter/y/cc9497/32.png) [@YamatoTwinkie](https://boards.straightdope.com/u/YamatoTwinkie)\ **Post date:** [November 15, 2011, 9:08pm UTC](https://boards.straightdope.com/t/is-my-freezer-more-efficient-when-full/603049/4 "2011-11-15T21:08:56Z")
> [@sachertorte](#): > > It depends. > > ETA: You could also fill it with something that has a LOW thermal capacity (think syrofoam, NOT WATER!!!) I was thinking large ziploc bags filled with air, and then sealed would probably work pretty well. ---
**Author:** ![Ponderoid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ponderoid/32/19221_2.png) [@Ponderoid](https://boards.straightdope.com/u/Ponderoid)\ **Post date:** [November 15, 2011, 9:19pm UTC](https://boards.straightdope.com/t/is-my-freezer-more-efficient-when-full/603049/5 "2011-11-15T21:19:55Z")
[The master speaks](http://www.straightdope.com/columns/read/2657/does-a-refrigerator-cool-more-efficiently-when-full). This column is about keeping a refrigerator full rather than a freezer, but I think the logic applies either way. ---
**Author:** ![johnpost](https://avatars.discourse-cdn.com/v4/letter/j/f17d59/32.png) [@johnpost](https://boards.straightdope.com/u/johnpost)\ **Post date:** [November 15, 2011, 11:16pm UTC](https://boards.straightdope.com/t/is-my-freezer-more-efficient-when-full/603049/6 "2011-11-15T23:16:41Z")
empty plastic milk jugs (gallons, halves, quarts) take up space, stack, come out quickly. ---
**Author:** ![bouv](https://avatars.discourse-cdn.com/v4/letter/b/bc8723/32.png) [@bouv](https://boards.straightdope.com/u/bouv)\ **Post date:** [November 16, 2011, 4:03am UTC](https://boards.straightdope.com/t/is-my-freezer-more-efficient-when-full/603049/7 "2011-11-16T04:03:27Z")
> [@johnpost](#): > > empty plastic milk jugs (gallons, halves, quarts) take up space, stack, come out quickly. That won’t work…it’s not so much about the space taken up as it is the mass. ---
**Author:** ![johnpost](https://avatars.discourse-cdn.com/v4/letter/j/f17d59/32.png) [@johnpost](https://boards.straightdope.com/u/johnpost)\ **Post date:** [November 16, 2011, 4:40am UTC](https://boards.straightdope.com/t/is-my-freezer-more-efficient-when-full/603049/8 "2011-11-16T04:40:43Z")
> [@johnpost](#): > > empty plastic milk jugs (gallons, halves, quarts) take up space, stack, come out quickly. > [@bouv](#): > > That won’t work…it’s not so much about the space taken up as it is the mass. loose cold air spills out of an upright freezer when the door opens. air in jugs is no longer loose. ---
**Author:** ![bump](https://avatars.discourse-cdn.com/v4/letter/b/7c8e57/32.png) [@bump](https://boards.straightdope.com/u/bump)\ **Post date:** [November 16, 2011, 4:43am UTC](https://boards.straightdope.com/t/is-my-freezer-more-efficient-when-full/603049/9 "2011-11-16T04:43:26Z")
> [@bouv](#): > > That won’t work…it’s not so much about the space taken up as it is the mass. Then fill them up with water! That gives you mass and volume. ---
**Author:** ![DSeid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dseid/32/20194_2.png) [@DSeid](https://boards.straightdope.com/u/DSeid)\ **Post date:** [November 16, 2011, 4:48am UTC](https://boards.straightdope.com/t/is-my-freezer-more-efficient-when-full/603049/10 "2011-11-16T04:48:08Z")
What about the effect of the contents, once frozen, acting as ice packs to keep other contents cold, buffering the temperature swings? I know that when our power has gone out a full freezer unopened has stayed frozen a long time. ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [November 16, 2011, 8:27am UTC](https://boards.straightdope.com/t/is-my-freezer-more-efficient-when-full/603049/12 "2011-11-16T08:27:52Z")
> [@bouv](#): > > That won’t work…it’s not so much about the space taken up as it is the mass. Why should it be about the mass? All you really need to do is stop whatever you’ve chilled from spilling out and being replaced by room-temperature air. Anything that simply occupies volume in the freezer will accomplish this. Water-filled bottles will make the whole system more stable thermally - as they will help to sink heat added to the freezer at any point, but the energy cost of initially freezing them is higher, and that will ultimately be wasted when you remove any of them in order to free up room for additional food. ---
**Author:** ![Annie-Xmas](https://avatars.discourse-cdn.com/v4/letter/a/ecc23a/32.png) [@Annie-Xmas](https://boards.straightdope.com/u/Annie-Xmas)\ **Post date:** [November 16, 2011, 3:55pm UTC](https://boards.straightdope.com/t/is-my-freezer-more-efficient-when-full/603049/13 "2011-11-16T15:55:20Z")
I keep a couple of those blue freezer packs in mine. My first rule when the electricity goes out is DO NOT OPEN THE FREEZER!! ---
**Author:** ![Machine\_Elf](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@Machine\_Elf](https://boards.straightdope.com/u/Machine_Elf)\ **Post date:** [November 16, 2011, 4:16pm UTC](https://boards.straightdope.com/t/is-my-freezer-more-efficient-when-full/603049/14 "2011-11-16T16:16:13Z")
> [@DSeid](#): > > What about the effect of the contents, once frozen, acting as ice packs to keep other contents cold, buffering the temperature swings? The duty cycle for the compressor will slow down - longer “off” periods AND longer “on” periods - but assuming the door is never opened, the time-averaged refrigeration power requirement will be the same for a full freezer as for an empty freezer because the rate of heat transfer through the walls will be the same in both cases. > [@](#): > > I know that when our power has gone out a full freezer unopened has stayed frozen a long time. Loading your freezer with mass will help in this regard. The rate of heat transfer through the walls is the same, but if the fridge is packed with mass, the rate of temperature rise (which is what we care about) is slower. ---
**Author:** ![constanze](https://avatars.discourse-cdn.com/v4/letter/c/f9ae1b/32.png) [@constanze](https://boards.straightdope.com/u/constanze)\ **Post date:** [November 16, 2011, 5:31pm UTC](https://boards.straightdope.com/t/is-my-freezer-more-efficient-when-full/603049/15 "2011-11-16T17:31:22Z")
If your freezer is permanently almost empty, why not trade it in against a smaller and newer model, which will also be more efficient? (A++ rating is now available). Advertise or ask which family needs a big freezer and sell yours to them. ---
**Author:** ![Dahu](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dahu/32/3416_2.png) [@Dahu](https://boards.straightdope.com/u/Dahu)\ **Post date:** [November 16, 2011, 7:27pm UTC](https://boards.straightdope.com/t/is-my-freezer-more-efficient-when-full/603049/16 "2011-11-16T19:27:07Z")
> [@constanze](#): > > If your freezer is permanently almost empty, why not trade it in against a smaller and newer model, which will also be more efficient? (A++ rating is now available). > > Advertise or ask which family needs a big freezer and sell yours to them. I would do, but I can’t easily move it. I swapped the old one several years ago for a slightly bigger model without realising that it wouldn’t quite move into the space without being lifted 7ft in the air, turned to the horizontal, then eased carefully back into place. This also involved removing & replacing several protruding devices. More trouble than I can be bothered with. ---
**Author:** ![DSeid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dseid/32/20194_2.png) [@DSeid](https://boards.straightdope.com/u/DSeid)\ **Post date:** [November 17, 2011, 1:35am UTC](https://boards.straightdope.com/t/is-my-freezer-more-efficient-when-full/603049/17 "2011-11-17T01:35:37Z")
> [@Machine\_Elf](#): > > The duty cycle for … Thank you for that answer. It makes perfect sense. ---
**Author:** ![Pai325](https://avatars.discourse-cdn.com/v4/letter/p/c68b51/32.png) [@Pai325](https://boards.straightdope.com/u/Pai325)\ **Post date:** [November 17, 2011, 1:39am UTC](https://boards.straightdope.com/t/is-my-freezer-more-efficient-when-full/603049/18 "2011-11-17T01:39:48Z")
If you hate to waste the energy to freeze water in milk containers, just wait a month or so and put the water-filled jugs outside and let it freeze naturally. Then pop them I the freezer. That’s assuming it gets that cold in Manchester. I’m afraid all I know about Manchester is that my great-grandfather came from Newton Heath which I think is close. ---
**Author:** ![constanze](https://avatars.discourse-cdn.com/v4/letter/c/f9ae1b/32.png) [@constanze](https://boards.straightdope.com/u/constanze)\ **Post date:** [November 17, 2011, 9:41am UTC](https://boards.straightdope.com/t/is-my-freezer-more-efficient-when-full/603049/19 "2011-11-17T09:41:19Z")
> [@Dahu](#): > > I would do, but I can’t easily move it. I swapped the old one several years ago for a slightly bigger model without realising that it wouldn’t quite move into the space without being lifted 7ft in the air, turned to the horizontal, then eased carefully back into place. This also involved removing & replacing several protruding devices. > > More trouble than I can be bothered with. Ouch. That is a bit akward. Do you have neighbours close by that want to share your freezer space, then? You freeze their lasagna, and in turn you get one free meal every x weeks/ 5% of the electric bill? (You’d probably need a meter to measure how much kWh the freezer uses).