Is Your Fridge Running (Efficiently)?
by Union of Concerned Scientists on 02.19.07
Appliances account for about 20 percent of a household’s annual electricity use and one of the biggest users of electricity is the refrigerator. If you’re in the market for a new refrigerator, see one of Union of Concerned Scientists’ previous posts on buying an energy efficient fridge.
You can make any refrigerator more efficient by making make sure it has a few inches of space behind it to keep air circulating around the condenser coils. Vacuuming your coils also can improve circulation.
Keeping your refrigerator too cold also can waste energy. The recommended temperature for refrigerators is 37 to 40 degrees (3 to 5 celcius) Fahrenheit and the recommended temperature for freezers is 5 degrees Fahrenheit (-15 celcius).
Keeping your refrigerator full also will help it retain the cold and cool more efficiently. If your fridge is sparsely occupied, you can add a few water-filled containers. On that same note, smaller refrigerators generally use less energy than larger ones. If your refrigerator is rarely full, you might want to consider replacing it with a smaller one.
See also: ::How to Green Your Electricity, ::How to Green Your Heating, ::How to Green Your Water, ::How to Green Your Dishwasher
For many of the more recent fridges you need to dust and vacuum under them. That is where the coils are. For many years I had assumed that the more recent fridges didn't have exposed coils. Then I looked underneath. Totally caked with dust. I had to go and buy a long feather duster to get access. I don't think many people realize this, and it is worse if you tend to sweep the floor towards the fridge.
Why do fridges run more efficiently when they are full? Doesn't it take energy to cool and maintain mass at a lower temperature? And if a fridge is too stuffed, airflow may become restricted.
A bit back TH posted a commercial from the UK that showed a bunch of kids running around sticking bricks in the back of toilets and in peoples fridges too (all to a cover of PinkFloyds The Wall). Just like a rock in the dessert radiates heat, a brick in the fridge absorbs cold air and causes the same effect as a full fridge (as mentioned in your article).
Since that video I had found some cracked marble and have put this on top of each of my shelves and turned the temp way down to less than 1 on the little switch. Its like geo-mimicry, instead of bio.
So TH, in theory this maintains a cooler temperature, but by how much? Would it actually prolong the period of time the thermostat takes to re-cool the fridge? Would this use less electicity?
What material would work the best? Porcelain? Marble? Slate?
You made me curious.
Hmm, I suppose that having more stuff in the fridge increases the thermal mass, which probably means that between cycles the fridge loses "cold" (or rather, warms) more slowly. It's kind of like a thermal buffer..
"Why do fridges run more efficiently when they are full? Doesn't it take energy to cool and maintain mass at a lower temperature?"
yes, but when you open the fridge door, the items inside don't fly out and carry that energy investment with them as air does.
As a foodie, I've kept a thermometer in my fridge and freezer (and oven) to make sure I'm running it at 38 degrees in the fridge, 10 in the freezer, and make sure my oven is accurate.
Those numbers on the dials inside don't reflect anything concrete, and the thermometers run about $2 apiece at the grocery store.
Knowing your fridge's temperature will also help your food keep longer since it'll be below the temperature that bacteria and mold thrive at and above freezing. Less food wasted = less food to grow and ship
None of these fridges are anywhere as efficient as converted chest freezer. The cold air remains inside simply because it opens from the top.
If you have the space, why not consider it?
Re: "when you open the fridge door, the items inside don't fly out and carry that energy investment with them as air does."
If this is the answer to the mystery of why a full fridge is more energy efficient, then why not place empty plastic jugs in your fridge to fill it up? Less air to escape and less mass to maintain at a lower temperature.
The only thing that I can think of is that it must take a lot of energy for fridges to start a cooling cycle. Near empty fridges would need short but frequent cooling cycles. Fridges with mass inside would need longer cooling cycles but less of them.