Refrigerators (tutorial)
Skip this if you know the physics of refrigeration. The
intent is to give an eco view of selecting a refrigerator.
The basics of refrigeration are simple. It works on the
principle that any gas gets hot if compressed and absorbs
heat when it expands. You can test this by feeling the spray
from a pressurized can, it is cold.
In a refrigerator the gas is expanded inside the box and gets
compressed outside. The heat produced from the compression
is dissipated in copper tubes and often has a fan to move the
heat away. All the gas is in enclosed tubes and it goes
around in a loop first compressed, then expanded. That's it.
The most important design factor from an eco standpoint is
insulation. If we can keep the heat out it will not need any
energy to remove it. Sounds simple, but the average
refrigerator isn't built to do this. If it feels cold on the
outside then lots of heat is getting in.
Another big heat loss occurs when a door is opened. For this
reason it is better to have top opening doors and multiple
compartments. Anything which keeps the air from flowing out
saves energy. Cold air sinks, so having glass shelves is
another way to keep the air from moving.
If the copper coils on the outside are large and need a fan
then you are looking at an energy monster. One way to move
heat away is to put the coils on top and let the heat rise
normally. That is how our refrigerator does it and it
eliminates the need for a fan. The only reason this isn't
popular is due to consumer demand. They want a refrigerator
that doesn't have vents on top and need room above for air
flow.
For those of us who like to tinker it is easy to build a
refrigerator. Simple designs use very little energy, are
quiet, and looks like a normal cabinet. This is sometimes
done in expensive homes and some people even build large walk
in refrigerators. The trick to doing this is "wood". Wood
is a great insulator and adding some foam makes it even
better.
If you don't want to make a refrigerator then it is possible
to buy wood ones, have one made, or find refrigerators that
include insulation. The cost of having one made is probably
excessive for one family, but a communal frig can be
surprisingly efficient.
Consumer tips say things like insist on a separate door for
the freezer. This is to keep heat in and minimize air flow.
Collecting all these facts leads to one conclusion. Keep it
simple, well insulated and small. Going from a monster frig
to something efficient saved about $5 a month ten years ago.
I don't know what it would be today. Probably close to $10.
When i campaigned to reduce the size of our frig there was a
perception that we were reducing the quality of life and
going backwards. After we began using the new smaller frig
the attitude changed to a feeling that we had moved forward
rather than backwards. This still puzzles me a little, but i
think the resistance was mostly habit and conditioning by
years of product advertizements. Once everyone experiences
the quiet operation and quality in an efficient frig it is
difficult to feel deprived.
jeff
