Draft cabinet / fridge

Ok I know I saw in a youtube video once that someone had installed something called a draft cabinet in their kitchen, which was a floor to ceiling cabinet that drew cold air from under the house, through the cabinet chilling the food that was in it, and out through the ceiling. So it worked like a powerless fridge or a chiller.

Does anyone have any more information on this, it seems interesting. I probably have the name wrong since I can't find any more info on it.

I saw this and have it in my favorites, but it's under some general name and I can't find it right now.  The guy lives in Australia and it is a tour of his passive 'designs', really interesting stuff.

I really like the idea.  It has been done like a small box fridge in cob housing too, without the fan.

The thing that bothers me with drawing air from under the house is that there must be an air space under there, and I was planning on no air space with a cob house.  I don't really understand the pros and cons regarding heating/cooling of a house that has a crawl space and one that doesn't.  Since I wouldn't need a crawl space for wiring or plumbing I was thinking I'd skip it, and help my house retain a constant temp better.  I suppose there are other ways you can draw in cool underground air than from one's house too.

Oh here it is - http://www.youtube.com/watch?v=bkt7UlKvoDk ;

Yep that's it! Turns out it was David Holmgren himself 

Also turns out it was Australia, so probably a very slight chance it would work here in Sweden...

          I also watch that video in youtube and I am really interested to it. After I watch that video I became really interested to it. I also want to try it on my home.

It sounds like a really "cool" idea.

Another one, for those who don't have a crawl space or want to insulate their crawlspace.
dig a trench out away from the house at least 20' and bury 4" pipe that comes up to the surface with a vented cover.  After the pipe enters the house crawlspace or from under the slab, then have it come into that box.

I've heard this principle would work just as well for the Entire house, as natural air conditioning if you had larger pipes AND  like 3 or 4 of them.  In that case you would want to have a vent direct at the highest point on the roof to take advantage of the chiminey effect. 

Erik:
How do you keep it from letting the cold in in winter? is the draft box super insulated as well?

Well, there is a couple of things here.

This "draft cabinet" your referring to is a good idea, but, yeah, it would need to be insulated, just like any refrigerator.  I think it would be most convenient to simply take an old refrigerator, that is well insulated and already has provisions for adjustable shelves and lighting, cut a hole in the top and bottom and connect Insulated ducting to it. 

Now this would be fine for winter months. But extracting heat or cold from the ground is difficult in this system because the ground is a consistent 55 degrees (approx.).  And refrigerators need a temperature range of 30 to 39 degrees.  Freezers even lower.  So in this passive system, it really would not work unless you live in a cold climate, and for only some months of the year. 

This system would work well for natural air conditioning, however, because a typical air conditioned temperature in summer would be about 75 degrees.  In the winter, I think, the system would work as a heat source if one were to connect the pipe directly to the vent in the roof.

And that connecting pipe should have some type fins to distribute the heat.  This would, in my opinion, supplement other heat sources to bring the room to approx. 72 degrees in winter.

As for the draft refrigerator idea,  I looked at an old house once, here in Wisconsin, and it had a wood box built into the outside wall that projected onto the front porch.  They were using this as a cold box in winter.  It wasn't insulated though, so not very efficient.

Frankly, given the exact and consistent demands of a refrigerator, and for efficient models (meaning a evaporator coil that uses natural convection to cool it on the back, and are well insulated) they don't use that much energy,  I would rather spend my efforts finding a way to generate that electricity rather than a permanent installation that you may not be able to control as well.

But how would you get it to warm in winter? If outside temp is -5C, ground temp is a constant 4C it is definately warmer, but you'd prefer around 20C in your home... So how would it warm? A heat pump? Then that becomes another story altogether.

In the winter, the warmer air being extracted from the earth would be approx 55 degrees, which could supplement ones heat source.  My thoughts were that some type fins on the pipes in the house, or metal rods going through the pipe and sticking out, or other manner of extracting the heat (think refrigerator type coils here) would be able to add heat to the living area via natural convection. 

Paddy82 wrote:
But how would you get it to warm in winter? If outside temp is -5C, ground temp is a constant 4C it is definately warmer, but you'd prefer around 20C in your home... So how would it warm? A heat pump? Then that becomes another story altogether.

This is the principle behind the ground-source heat pump.  Yes, it does require a secondary heat source in the winter.  (Think rocket mass heater.)  However, the secondary heat source doesn't have to be as efficient or powerful as a heater that is the primary heat source.  If you bury the tubes 1.5 to 2 meters underground, the temperature there is closer to 10C than to 4C.  The air coming into the house is bringing fresh air into the house (remember -- people need to breath, houses don't) at 10C and so won't need as much energy to bring it up to 20C -- only a 10C difference.  Air that comes straight from the outdoors is -5C, meaning a 25C difference -- more than twice the temperature difference from the air from the ground source.

Jami McBride wrote:

The thing that bothers me with drawing air from under the house is that there must be an air space under there, and I was planning on no air space with a cob house.  I don't really understand the pros and cons regarding heating/cooling of a house that has a crawl space and one that doesn't. 

If you're going to be building on slab, then you need to be sure to thermally insulate the slab from the surrounding earth.  Otherwise, you're going to have your heat sucked out through your floor.  If you build on a crawlspace, you need (and I cannot emphasize this enough) you NEED to have your crawlspace sealed.  The latest studies have shown that open-vented crawlspaces have higher levels of mold and structural deterioration because the water vapor gets in there and can't get out.

Vapor seal the flooring, and insulate the walls and the underside of the floor (the top part of the crawlspace) for the most efficient heating and cooling.

You guys need to think outside the box.  First of all, while the ideal temperature for a refrigerator is around forty degrees F, any amount of cooling will be helpful.  So, if you can't get your box down to forty degrees F in the summer, take what you can get!  If temperatures are critical for some items, have a smaller efficient refrigerator (which requires less electricity).  Or, cook differently.  Instead of making a large amount and putting leftovers in the frig, cook smaller amounts and eat it all at one meal.  Instead of butchering a whole goat or steer in the summer (or buying big packages of meat), do a chicken or a rabbit -- and if your family can't eat all of a Cornish cross chicken or a New Zealand rabbit at one meal, then raise a dual-purpose breed of chicken, or Florida White rabbits, for smaller carcasses.  Instead of making highly perishable desserts with a lot of egg in them in the summer, make fruit desserts -- fresh berries or fruit with a little sweetener and maybe a dollop of cream is pretty good in hot weather!  Or just eat a slice of melon. 

For things that you buy that need to be refrigerated, like catsup, buy smaller containers.  Make your own mayo in small amounts.  Turn your milk into kefir (which keeps for quite a while even at room temperature).  Instead of baking a whole big batch of bread to last the whole week, make a few muffins or a baby loaf each day.  (A sourdough crock might simplify this process a little.) 

In the winter, if you are in a cold climate, move your refrigerated stuff!  Instead of keeping it in the warm kitchen, make a cabinet in a cool entryway and use that as your refrigerator.  Or have a cool pantry off the kitchen (or a root cellar under or behind the house).  When we lived in a cabin in the Interior of Alaska with no electricity or running water, we kept some stuff in a hole under the floor -- a small root cellar.  We had a box by the front door for stuff that needed to stay cool -- a non-electric refrigerator.  And there was an old propane cook stove outside the door that we used for a freezer most of the winter, until daytime temps got too warm.  It kept the stray dogs and the wolves out of our meat.  Part of the winter, you could also keep frozen stuff in a vehicle that wasn't being driven, but the windows would need to be covered when the sun started to stay above the horizon long enough to warm the interior of the vehicle. 

You can't always exactly replicate the jobs that electricity does for us, if you don't have electricity.  Sometimes you have to go with the flow and use what you have available, even if it isn't precisely the same.

Kathleen

Muzhik wrote:
Vapor seal the flooring, and insulate the walls and the underside of the floor (the top part of the crawlspace) for the most efficient heating and cooling.

This is soooooo true!

But going back to the cabinet/fridge idea:

Set the refrigerator part to 38 degrees Fahrenheit (3°C) and freezer part to 0 degrees Fahrenheit (-18°C).  Bacteria grows most rapidly between 40 degrees Fahrenheit (4°C) and 140 degrees Fahrenheit (60°C). Zero degrees Fahrenheit (-18°C) is the temperature, suitable for long term frozen items preservation.

It is obvious to me that these CF's are NOT refrigerators, but cold boxes.  And that we are talking about two different things - (1) storing foods that are only going to be around for a few days, versus (2) storing foods for the long term.  The temps quoted above are for long term storage of easily spoiling foods (specifically meats, animal products).

Even though the temps of a CF may not be cold enough for long term storage, including/excluding meats - they are cold enough for short term storage and the long term storage of cold storage veggies and fruits such as carrots, apples, cabbage, and such. 

I use my garage to storage many of these items during fall, winter and spring here in my zone with no problems at all, and it stays mostly in the 40's range.  This is very handy when I make huge pots of foods that won't easily fit in my refrigerator.

I think the addition of good isolation to a CF (cabinet fridge) is a great suggestion, as well as moving the air with a small fan, for the removing of any off gassing from fruits/veggies and clearing off moisture accumulation. 

Trust me, even without refrigerator temps these boxes are very very useful additions to the homestead.  Much like a light version of a root cellar.  In the summer time one may have to move food that spoils easily to a proper refrigerator, but the cold cabinet is still a nice addition and has many uses.

On the flip side, in the winter - I also find a warm box (cabinet with heat from something like a food dehydrator, or light bulb on a timer) just as useful and necessary to fermenting as the cold box is to food preserving/storage.  Making yogurt, kefir, kombucha, ginger ale and other fermentation needs a warm place to sit without taking up space in one's oven. 

If it's more like 10 degrees C, that's good news. But is that true for all non-permafrost latitudes? This would really make massive difference (to the better) to my plans
I have heard it was 4 (at least here), but I hope whoever told me that is mistaking.

Anyway, if you didn't want to use a draft cabinet doubling as ventilation you could just divert the air back outside from the top.

Just what I was thinking about mainly using the draft cabinet for vegs. That would free up a lot of room in your fridge so you could make do with a smaller one or just a not-so-stuffed one, saving energy too.

Really good idea about a warm box for fermenting! Although hard to find a warming lightbulb nowadays, since they're all illegal
An idea would be to build one to the back of your fridge, since that gets pretty warm.

it occurs to me that in a hot climate stuffing your fridge into one of these(or just building one around the condensor coils on the back) so it was operating at less temperature gradient would boost efficiency a lot

kinda like how much better a ground source heat pump works in winter than one that exchanges heat with outside air

If it's more like 10 degrees C, that's good news. But is that true for all non-permafrost latitudes? This would really make massive difference (to the better) to my plans 

I'm on the border between zones 5 and 6.  Around here, the ground-loop heat pumps all assume a 10C year-round constant (plus or minus a couple of degrees) at about a 2-meter depth.  It tends to be easier around here to hit that 2-meter mark because of the depth needed for footers to reach the permafrost region.  Since you have to dig that deep anyway, the great majority of houses here have basements.  Commercial buildings like convenience stores are built on slabs that have been thermally insulated from the ground.

However, this depends on what zone you're living in, so...

Muzhik:
The zoning map of countries are not international. I don't know what country you live in, but according to the Swedish zoning, I'm in zone 1, which is the southernmost and thereby the warmest. I don't know what that corresponds to in your country, so it is often better to compare latitudes (Here is 55 degrees N).

I just found  this site that "translates" eurozones to USDA zones. However, USDA zones only consider temperatures, whilst eurozones also considers, type of summer, length of winter and depth of ground frost. Anyway, it says I'm in USDA zone 7.
http://www2.dicom.se/fuchsias/eurozoner.html

Good point, Paddy.  Here in the US, the Sunset growing zones for the western half of the country are by far more accurate than the USDA growing zones.  Unfortunately, the eastern half of the country does not, as far as I know, have anything comparable.  The Sunset zones take into account elevation, summer frosts, and so on.  (Elevation is a huge factor in most of the Western United States -- we are technically in USDA Growing Zone 6, but because we are at 4200' elevation we can have frost in any month of the year.)

The nice thing about this type of climate is that no matter how hot it gets during the day, it cools off at night, making another type of cooler practical.  This is the one that sits out under the open sky at night -- you open it at night and allow the contents to cool off.  Then during the day close it and move it into a shady location.  I'm told (haven't tried it yet) that this type of cooler can actually freeze stuff, or come very close, but it's not as convenient as a refrigerator, or even the draft cabinet that this thread is about.


Kathleen

Paddy, Hur mår du?  Jag bodde i Mora under sex månader med en vän.  Jag lärde mig nog svenska för att träffa svenska flickor, men jag är rädd att jag har tappat bort vad jag har läst.

I live in Iowa, near 41 degrees N.  I didn't even know the zones were from the USDA, as I've only used them to compare building and insulating practices.  In Sweden, you have the advantage of getting some warmth from the Gulf Stream.  All we get from the Gulf is humidity.  There is no such thing as a "dry heat" in Iowa, which is why evaporating cooling (swamp coolers) don't work here at the time of year when we need cooling the most.

Muzhik:
Din svenska låter perfekt!

Yes, thank god for the gulf stream, without it we'd all have to hibernate year round.

Guys take a look at the following for an idea:

http://fourmileisland.com/IceBox.htm

timby wrote:
Guys take a look at the following for an idea:

http://fourmileisland.com/IceBox.htm

Love it.

Except us North Floridians can't exactly do this. We do get freezing nights but only about 10-15 per year, and usually only in the night. Cold winter days, but rarely below freezing.

We might be able to use some of the passive fridge techniques: Use a standard freezer to create a big block of ice, insert into a well-insulated cabinet for several month's worth of cold.

Or: Add extra insulation to a standard top freezer/refrigerator. Put a large bucket/tub of water in the top section. I believe there is a vent between the freezer and refrigerator sections, else cut one.

Or: Easily convert a standard chest freezer into a refrigerator. Uses a mere 0.1 kWh a day, which is 1/10th a standard refrigerator!

Maybe a combination of the last two choices? Would require two freezers, probably chest freezers, if you've got the space.

Greenpa claims to have gone 30 years without any refrigerator. Food for thought (no pun intended) 

We can't use it here either (North Texas) however, anyone in a northern clime should be able. Also, take a look at the solar hot water section. Has a great design for that.

In cob construction it is very useful to remember the thermal flow through the mass.  Actually, it's good to remember this with any type of construction.  The cabinet won't work well in just any old wall of the house.  The access should be designed (kitchen, pantry) so that the cabinet is set into the NORTH wall in the northern hemisphere, and into the SOUTH wall in the southern hemisphere (if in temperate zones).  In the temperate zone, it is not absolutely necessary to draw air from under the house. 

I live in sourthern Missouri, right at the northern border of what might be considered the South in the United States.  My house is mobile home retrofit with a hybrid wall system of six inches of light straw clay and six inches of cob.  My cabinet is located on a NORTH wall of a small pantry room.  Air circulates through the cabinet from the shady side of the house - that's right - outside air.  Even at 95 degrees ambient outside, the mild inside stayed at 54 degrees.  Not refrigerated, but certainly low enough to keep it from spoiling within the use time.  Where is the cool coming from?  From the walls themselves. 

In summer, the cabinet is only covered with a frame with 1/4 inch mesh and cheese cloth, which is moistened with a spray bottle each day.  In winter we can reach -10 F.  I have a cupboard door that I use in winter, but items too close to the outside still tend to freeze.  The temp. is a little higher each inch or so closer to the interior of the house you get, so that, the items furthest from the outside in winter remain refrigerated but not frozen.  The opposite holds for summer.  Items the furthest from the center of the house remain cooled (not refrigerated), whereas items closest to the inside of the room are cooler than the house, but not as much as deeper in the cabinet.

If you place the cabinet not in the kitchen but in a separate room, like I have done, which is shut off from the rest of the house, that room never benefits much from stored thermal mass from either solar gain or from heat sources such as wood stove.  With the cabinet in that environment, and being cooler than the room (because of the nature of earthen walls), it's almost as good as a refrigerator. 

Incidentally, we save ice cut out of the pond, packed in sawdust, in the same little room.  It lasts well into august no matter what the temp. outside is.  With ice in the room, the cabinet becomes a true refrigerator!

Don't know if anyone has posted this yet - refrigeration for hot climates:  http://www.scienceinafrica.co.za/2004/september/refrigeration.htm

Cloud - thanks for posting your experience with the cabinet fridge.  I have a couple of questions, as I can't exactly picture your set up.  (1) is your CF surrounded by a thick cob wall on the entire outside?  And open in the summer only on the inside?  (2) Have you considered or try adding form insulation?  (3) do you have any pictures you can share?

Ludi - regarding The Zeer Pot
From what I've seen of people trying them their results were unsatisfying.  Seems our standard of acceptable 'cool' is not perfectly achieved with the pots.  And the return for effort sends people looking into other low tech methods.  Maybe you know of some with better results and could post a link?

Ludi Ludi wrote:
Don't know if anyone has posted this yet - refrigeration for hot climates:  http://www.scienceinafrica.co.za/2004/september/refrigeration.htm

It's a brilliant idea, but only for dry climates. Evaporative cooling just won't work in humid locations like North Florida, where I live.

I'm thinking of building a cold cabinet in an area of my house that has a crawlspace (a three season porch that I plan to have insulated). My thought is to bring the temperature down to refridgeration range by using the top shelf of the cabinet for a slab of ice and making it an ice box/cold cabinet. This way perhaps I'll be able to eliminate the need for a refridgerator altogether. I will still have a freezer, but my overall energy consumption should be decreased.