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Old 07-28-2016, 08:18 AM
Machine Elf Machine Elf is online now
Join Date: Feb 2007
Location: Challenger Deep
Posts: 10,734
Originally Posted by jtur88 View Post
This is similar to a question I've asked in a couple of forums, and never got an answer.

Is the heat exchange greater if I leave the refrigerator door open while making a sandwich, or if I keep wafting the circulation by opening and closing the door several times to take things out and put them back? In other words, was my mother right or wrong when she yelled "close the fridge, you're wasting electricity".
I think the buoyancy-driven convection associated with leaving the door open for a solid 5 minutes is going to warm things more than just quickly opening/closing the door a few times. Either way I think the cost of the energy involved is pennies.

For best efficiency, think about what you want on your sandwich, then grab all those items in as few visits to the fridge as possible. Put the items back (in another single visit) as soon as your sandwich is made so that you minimize how much they warm up.