Refrigeration

Part 2: Heat transfer

Heat transfer is an interesting part of science. Your refrigerator uses electricity to displace the heat inside the fridge to the exterior of the fridge, and keeps these environments isolated through the use of insulation and seals. As soon as any contents (say, milk or a margarine tub) from inside the fridge are moved to outside the fridge (the counter, the table) you have begun to let the heat in the room transfer into those contents.

When you replace the margarine tub back into the fridge, your fridge is once again consuming more electricity to displace the ‘new’ margarine tub heat back into the exterior fridge environment. My point being that the longer you leave items outside the fridge (with the intention of returning them) the more energy will be consumed to re-cool them and get them back to that storage temperature.

This energy transfer effect can be even more considerable since your margarine tub has absorbed the ambient room temperature. If it is winter, your margarine tub has been warmed by your home heating systems energy. Some of that heat will come back to the room from the fridge coils, but the inefficiency of the conversions is an electricity losing battle.

In our house, especially with two little children, it almost seems like a daily ritual to have our margarine container turn warm and soft, only to be placed back in the fridge to be cooled and hardened again. Much as I might like to, I cannot always police our energy situations (much to my family’s regret, I’m sure). I wish I could quantify the amount of electrical consumption this adds to our lives–sometimes the actual number can help back up my policing!