Naked Science Forum

Non Life Sciences => Technology => Topic started by: thedoc on 03/06/2016 13:50:01

Title: What uses more energy, leaving the fridge door open for 15 seconds or opening and closing it twice?
Post by: thedoc on 03/06/2016 13:50:01

CHEEKOS asked the Naked Scientists:
   IF I AM GETTING A GLASS OF WATER FROM THE FRIDGE, DO I CONSUME MORE ENERGY BY LEAVING THE DOOR OPEN FOR 15 OR TWENTY SECONDS, OR OPENING AND CLOSING IT TWICE?
What do you think?

Title: Re: What uses more energy, leaving the fridge door open for 15 seconds or opening and closing it twi
Post by: chiralSPO on 04/06/2016 04:00:14

Unless your fridge does something particularly energetic every time it is opened and/or closed, leaving it open will certainly require more energy.

Title: Re: What uses more energy, leaving the fridge door open for 15 seconds or opening and closing it twi
Post by: wolfekeeper on 09/07/2016 15:06:34

Probably not a lot in it. If you open the door twice, widely spaced, that's probably worse.

In both cases you're primarily just dumping the cold air in the fridge on the ground, but air has low heat capacity, so it's not a big deal. Still, once you've dumped it, you've dumped it, so opening and closing it twice makes little difference unless the temperature in the air has recovered significantly (has been cooled by the food or the compressor has kicked in).

If you open and close it twice in 20 seconds it's about the same as just opening it for 20 seconds; but if you open it twice, half an hour apart then it's probably better to just hold the door open once for 20 seconds.

Of course you could get a power meter and ... try it. Science!