In the break area at work, they have a few crappy gossip magazines on the table (don’t know who brings them in, the one I’m referring to is called “That’s Life“). I don’t usually read them, but I was grabbing a drink and noticed the page had been left open at a ‘tips’ page.
One of the tips was something like this: “If you have freezer which isn’t full, fill empty milk cartons with water and put them in. These store the cold meaning your freezer won’t have to work so hard.” (Words to that effect, anyway). There was also a cheesy picture of a guy with a milk carton filled with water standing next to a freezer.
I had to do a couple of double-takes when I read that. Speaking as someone who doesn’t know much about physics (did an A-Level in it, but have forgotten most of it!)… surely that can’t be right! To start with, your freezer would have to cool down the cartons of water to form ice – this would take energy. Then, the freezer would have to maintain the temperature to keep them frozen (taking more energy).
But what I can’t get my head around is the fact that having what is essentially a great big block of ice in your freezer would actually help keep it cool. The question comes down to: does it take less energy to keep a block of ice cool, or a block of air?
I’m guessing that it takes less energy to keep air cool, because it’s more dense. But I could be wrong on that (my old physics teachers would probably be shaking their heads by now at my terrible forgetfulness). Thus, a completely empty freezer would do less work than a freezer loaded with ice.
Am I going mad?!