5 hours ago, paulraphael said:
That's the folk wisdom, but it doesn't turn out to be a big deal. The amount of thermal mass of the air in the fridge is minute ... it takes very little energy to chill a few cubic feet of air from room temperature to 30-something.
If you calculate the thermal mass, of say, 20 cubic feet of air, and look at the amount of energy it takes to raise it from 4°C to 22°C, it's equal to 0.0004 kilowatt hours. If you assume a refrigerator isn't that efficient, and takes twice as much energy to cool that air back the other way, you've got .0008 kwh. At our current price of 19.2 cents per kwh in NYC, this is 0.015¢ to open the door and let out every molecule of cold air.
So it should go without saying that it makes no difference if you open the door for 5 seconds or half a minute. You use more energy putting in a jug of room temperature water and letting the fridge cool it.
That is the long way around to what I was saying , but yes the time to really save on energy when it comes to fridges and freezers, is when you buy them. Buy the most efficient unit you can afford, and after that just use it whatever way you normally would. https://www.energystar.gov/products/appliances/refrigerators
