Finally catching up with this thread.
[Joel Gagnon:]
| Better controls (including separate thermostats for freezer and
| refrigerator compartments and the needed ability to self-adjust
| the cooling to each compartment) would cost more, of course, and
| so far manufacturers don't see much of a market for high-end
| efficiency. The low-hanging fruit of energy efficiency has already
| been picked, with better insulation and more efficient
| compressors. Since the currently-produced products are not
| designed for the longevity of their predecessors, further
| improvement in efficiency could be rapidly introduced. I'd like to
| see a return to durability along with improved efficiency.
Joel probably already knows about this, but I'll mention it
anyway: there is at least one company that makes incredibly
efficient refrigerators: Sun Frost (sunfrost.com). Their models
typically use about one fifth the energy of a conventional
refrigerator. Since the refrigerator is one of the biggest energy
sinks in the average house, this difference is a pretty big deal.
The efficiency of the Sun Frost units appears to be due to a
combination of several intelligent but far from complicated
engineering decisions:
- Lots more insulation than the typical refrigerator (the company
got its start making vaccine refrigerators that could keep the
contents cold through power outages in developing countries).
- Separate compressors with separate thermostats for the freezer
and refrigerator compartments (as mentioned in Joel's post).
Sun Frost also makes a two-compartment deep freeze with
separate compressors so that you only have to run one if the
freezer is only half full (and can also keep the two
compartments at different temperatures, though I'm not sure why
anyone would want to do that).
- Placement of the compressors and coils on top of the
refrigerator instead of behind it so that heat rises up away
from the compartments (duh). This also makes it much easier to
vacuum the coils when they get dusty.
- Omission of the "frost free" feature. Turns out that much of
the energy used by conventional refrigerators goes into drying
out the air inside so that ice doesn't build up. Without this
feature, you do have to actually defrost the freezer part every
couple of months; but this is vastly easier than chipping ice
out of old refrigerators that lacked frost-free operation, for
two reasons: first, there aren't any irregulaties to get in the
way, just smooth plastic, and second, you can turn off the
freezer and put that stuff in the fridge part while you're
working, which only takes a few minutes once the freezer comes
up to room temperature. Also, the interior of the fridge part
gets kinda moist during the summer, but there's a huge
advantage to that: the higher humidity keeps veggies *much*
better than in a conventional refrigerator, and that eliminates
the need for separate interior compartments to protect
vegetables and meats from the dehydrator.
So what's the down side? They're insanely expensive. Each unit
is handcrafted in Arcata, which takes about six weeks, and then
shipped clear across the country, which adds another few hundred
dollars. The total can run upwards of three grand... which
explains why you don't see more of these. They're gorgeously made
to your exact specifications, but that hardly compensates for the
expense; and as a consequence, they don't have much use outside of
PV-powered households (which is why we have one).
The irritating thing about this is that none of the design
decisions listed above is inherently expensive. As far as I can
tell, the high cost is due entirely to the fact that these units
are not mass-produced (and the fact that they have to come a long
way to Ithaca, which points up the basic inefficiency of extended
supply chains). Higher energy costs in the future will probably
lead to big changes in both these areas.
The Sun Frost site has some pretty cool papers on "Concepts for
Sustainable Living":
http://sunfrost.com/concepts_sustainable.html
I love the energy efficient shower -- much more sensible than the
conventional arrangement (just as with the refrigerators).
Jon
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