Solar Aircon & fridge.

[StormCountry]

Hey all,

Wondering if anyone has any other plans or success with solar air conditioning.. as I understand most on here dont seem to have a use for it (the reverse is true) but here in the far North of Australia, temps around my block are often 37c + with dewpoints of up to 29c !!!!  Not nice! (although the spectacular storms make it somewhat worthwhile).

Ive encountered some designs based on the kero/gas fridge principles, using heat instead of mechanical compression to compress the refrigerant.  The vapour compression styles seem to work quite well.  The principle of AC Ive not found with regard to the whole thing, so Im wondering if anyone has tried it?

The best designs Ive seen so far are for a solar freezer, using the heat collector to boil an Ammonia/H20 and H2 solution instead of a compressor.  Very basic stuff, and it seems somewhat successful, though Ive not seen it applied to AC cooling.

Im going to whip something up in the coming weeks to muck about with it, but will be sure to be safe.. Im not too concerned about NH3 leaking as I'll initially (until time proven saftey record of homebuilt dodgey AC) put the cooling room away from the dwelling and maybe pump a supercooled solution from the unit to the dwelling in a pseudo evaporator setup to absorb heat.  As opposed to just having the homebuilt evaporator in the lounge room charged with high pressured Ammonia !!! (eek)

I'll apply the same principle to the fridge setup but obviously use a heatsource overnight.

What I've been thinking is perhaps a thermoelectric (pielter module) setup, by applying 12v/3A to the thermopile, one side is +50c and the other is -20c.  The module DOESNT provide the cooling per se, what I'd like to do with it is use it as the heat source to compress the NH3 solution, and directly under the module, use the cool side on the condensor of the unit (perhaps in a large solution to increase efficiency)

So basically :

Thermopile :

    -hot- ---> Boiler for NH3 sol      

-cold- ---> Immersed in solution thru which condenser pipes travel through (below ambient due to thermopile action) to condense the HP gas back to fluid

So thusly nighttime AC or fridge should only draw 3A during compressor 'on' times as controlled by an easy thermister cutoff circuit.  3A would be somewhat small for the amount of cooling available from a system of this size Id imagine.

Holes in this plan? or ideas to add? Cheers in advance!

 Any other ideas or plans would be most appreciated.. I'll post my progress as far as it goes.. as we've no lack of sunshine here (except storm and monsoon seasons which are cool anyway)

[MelTx]

  Hi Storm Country..... An A/C system does not  cool the area..It removes heat... the four things an A/C does:

 Removes --- Heat & moisture & dust also it circulates the air ...You have to circulate the room air over the cooling coils to remove heat.

You really need about 400 cubic feet of air  circulating... this takes a lot of energy...By the time you bought

all the componets to build a from scratch, you could buy a ready made A/C and run it for a year...The ones they make now are very efficient machines.

  The engineeers have spent 1000 of our lifetimes perfecting the products...Some wheels can be reinvented and some cant...hope this helps some..

[benjamindees]

Here's what I've found:

http://www.fridge.lionheart.net/descript.htm

There are companies that make small ammonia absorption coolers and gas powered air conditioners.  I've lost my links, but if you google around you can find them.

The principle for air conditioning isn't any different than for freezing or refrigeration, but the sizing may be different.  Solar sounds like the best means of power by far.  I would use a concentrating solar collector.

[Aelric]

A few ideas.   I have been looking into this myself.  So far the ways of cooling are absorbtion (NH3) evaporation (swamp cooler) and a few others like thermo-electric and vapor based ones like the HCFC kind that big companies like to say is best.  There are also a few others, One called "Greenfreeze" that uses butane (very small amount) also the propane ones (I think they are NH3 with propane as heat source) and another I stumbled on recently using Metal Hydride.  This particular one is being really explored in Japan where their laws are a bit more stringent on HCFC's they want to get rid of all of them.  There are already some Generator/Refrigerator units available that use fuel cells and Metal Hydrides, as the Fuel cell consumes the Hydrogen the endothermic reaction of the Metal Hydride releasing H2 is used to cool things.  Metal Hydrides use an absorbtion/release cycle of hydrogen to produce heat or cold.  Also could be used for storing hydrogen fairly efficiently for Auto or Home since Metal Hydrides only smoulder if exposed to open flame and they greatly increase the amount of Hydrogen that can be stored in any given space.  There is a neat writeup on it at http://www.homepower.com/magazine/downloads_hydrogen.cfm  just click on the link for Hydrogen storage.  Great article.  He doesn't go into how it could be used for refrigeration just suggests the possibility.  In his article he says that during the release of Hydrogen (sent to his H2 BBQ grill) the tank actually formed ice.  During the absorbtion cycle the tank got very hot.  This is the technology I am gonna look into soon.  I plan on making a lawnmower run on H2 then playing with Metal Hydrides, possibly using an old C02 tank like he did in the article I mentioned.  If it pans out Metal Hydrides would be a great way to heat or cool, no toxic chem's, just boosting efficiency of a system I plan on using anyway.  Want to one day convert a gas powered vehicle to H2, or if Fuel cells come down in price maybe build or buy a Fuel Cell car :-)

Anyway thats just my two bits.

[nothing to lose]

 I haven't tried any of it, too many other projects, but I think I might have seen one of the systems you mentioned, kinda sounds like it. Made about 10lbs ice by boiling amonia in a solar tube with an ice melter type salt, ran through a coiled cooler, driped into a condenser tank in an old freezer or something. When solar tube cooled an Ice melter salt in to tube would absorb amonia again and the amonia in the condeser tank in the freezer would boil off taking the heat with it and freezing the 10lbs of ice.

 Sound like about the same one?

 I was thinking if the solar heated tube/pipe were able to pivot up and down by the wieght of the amonia contained in it that it would work far better for a larger scale perhaps. Say make a long wall above the tube for shade, when full of amonia the pipe would swing down into the solar collector heated area and boil off the amonia from the salts inside. As the amonia boils off the pipe becomes lighter and raises behind the shade pannel where it cools off and then abosrbs the amonia agian into the salts, becomes heavy and lowers into the heated area again. This pivot system should then cause a cycle of freezing. I beleave in the system I looked at he was getting 1 cycle per day in a stationary tube always heated in the sun till night then cooling till morning and was only doing 10lbs ice per day. It has been awhile but I remember it fairly well. Was something I planned to try someday maybe but I dought I will ever get around to that one myself now.

For airconditioning then I would think a cycling system like I mention using that basic type design he had but cycling, you could cool some type of liquid perhaps and circulate that instead of freon or such. Say if you used a safe anti-freeze good for -10F like automobil types or that stuff for water pipes in motor homes and pump that through the freezing chamber and a tank. Cool the anti-freeze as cold as it will get and then pump it back into the cooling system in the house. I have no idea how cold you could actually get it but if he could freeze water and make ice with his system then we know it will get freezing cold anyway right

So that stuff for motor homes is to be used in drinking water lines and should be safe in case of spills or leaks I would think. Everything involving amonia could be located outside where safe and circulate only the antifreeze through the house in a closed loop system. Perhaps even build a pre-cooler into the system where the warmed anti-freeze goes through a underground loop or tank if your ground gets cold enough the remove the house heat from it, then should take less to cool it agian.

As for pumping the cooled liquid then, there is a post on here somewhere of a sterling heat pump. Was a simple easy to build design involving some tubing, couple fittings, and 2 one way valves. When the one side heats water expands forcing it out a top valve, water cools and contracts sucking in more through a bottom valve. Now if you can freeze water or cool the anti-freeze with your solar heat it seems to me it would be no big deal to make a pump like this and use solar heat to operate it. You don't want to heat the liquid you are cooling of course but I would think some thought into this would provide a way to make the water pump operate a second pump or diaphram unit that would move the cold liquid with out heating it. If so then you have your cold for cooling and a system to move it also.

 Now last part of the system is a way to move hot air through your cold radiator in the house. Fans normaly use power. You should have alot of heat difference here though if the system is working. Perhaps a small sterling engine turning a fan?

 As I see it the sterling engines work on a difference in tempature from hot side to cold side. Air inside moves to the hot side where it expands and the engine moves a piston outwards and inside a displacer moves pushing the hot air to the cold side where it contracts and thus sucks the piston back in again. Displacer then moves pushing the cold air back to the hot side to expand again. Pretty neat little engine.

I plan to build a few different types out of aluminum ingots and copper with my lathe/milling machine. Anyway some of these are more working models and don't have enough power to do much work if any (mine will be a working novelty to begin with) but a good one should run a fan and I would think hot air in the house and mounted to a cold condenser/radiator you would have enough temp difference to run one of these pretty nicely with a fan moving air.

I have seen some for sale made to sit on top of a wood burner to run a fan, they were expensive and I never tried those. The little one I built from cans worked though it's just a working toy, for me anyway and didn't do anything but turn a flywheel and rock a beam but it was nice to have till it got broke.

 The design for what I built from cans is on this site somewhere, that's how I knew what to build. It is that plan I will be using for machining my aluminum and copper parts to build a more solid one that won't get broke!

 I don't remember exactly who posted the design off hand, kinda a slow brain type night tonight. I should be asleep right now and would be but it sounded like a digital alarm clock factory here when all the UPS systems started beeping! Lost power for about 2 minutes or less and just now had another round. Oh the joys of being on grid at this house

[stop4stuff]

it was me NTL

here's the link

http://www.fieldlines.com/story/2004/12/7/204910/690

[StormCountry]

Thanks MelTx : Yeah, Im quite aware that there is no such thing as cool, just the relative absence of heat But cheers.. Though not to be rude, Id argue that air-con companies don't invest millions in research to create electrically efficient machines, moreso more cooling, period.  Most household products are made guzzlers for the simple reason that on the grid, and connected to a standard point (not even a hardwired point) there is 10A at your disposal.  The last thing big manufacturers are interested in is dropping power requirements.  There simply isn't enough of a market for low current devices.  Sure the market has now become 'somewhat' more aware of the efficiency related to domestic products, but its seldom an issue when purchasing a new unit. Its about manufacturing costs, and getting the product out.  I can tell you that I dont 'use' most common household appliances for this reason.. I dont have the ludicrous wattage required for a washing machine (without the motor change) nor a kettle or a toaster, Im quite aware that if I want 'efficient' products, I have to do my research for myself.  Not being rude, so please don't think Im taking a dig! just that I've not the 'faith' in devices that can be compared like this.

The same product :

A): Solar fridge that produces a heap of ice from solar absorption (free)

B): A freezer that draws 200w from my battery bank.

I could compare wattage and naturally it would come out about the same (given relative Watt per Sq M from solar heating) but I'd prefer to use all that spare heat on the compressor side of my en-visioned cooling system.  Thanks for the response though! and ignore me just being my arrogant self!

BenjaminIndees :   Cheers for the link! Yeah Im concerned mainly about the size issue, and think that perhaps even if it cools a relatively small area (small cordoned sleeping area) it would be a great asset.  Like you say, solar would be the best (and otherwise most wasted) heat source for the compressor side, esp in this very hot place! Cheers again!

Aelric : Thanks for that info, Im well in touch with the common absorption and vapour compression type AC's but literally have NO idea with the metal hydride chemical reactions you are mentioning! It sounds exciting, and probably another whole new technology to sweep the planet, if not in cooling, like you said, the safe storeage of H2.  If you do bump into any awesome uses, be it kinetic or thermal, drop me an email !! haha.. (then I'll swiftly sell your plans to a large manufacturer) kidding of course.. they generally aren't interested in us small timers and our projects.  Thanks for the input, fascinating too!

Nothingtolose :  Yeah, that is the one I speak of, I was impressed with it, and have seen it featured in a few places, the salt base seemed to be a great replacement for a gravitational cycle device, though the only thing Id have concerns with is the integrity of the ammonia and/or the salt base over time.  Fascinating idea with the kinetic aspect of the other unit cycling up and down.  I see you understood exactly my concerns with having the NH3 so close to a dwelling, so pumping supercooled fluids to an evaporator like setup in the house.  Thus taking away any chances of toxic explosion or leak.  Esp given the probably huge amount of NH3 Id need to make the unit relatively efficient, though Id not use water, Id prob just use a liquid with a very low freezing point.. (that would prob be toxic anyway lol)

The fan of the unit could be a just run from a simple panel on the roof, Ive a 4 ampre 12v panel that would more than do the trick, or even use a thermopile to use the heat/cool difference (heated from the condenser area of the unit, cooled exposed to ambient temp) to run the fan.  

Glad to hear someone else suffers the wrath of a lazy grid! my parents house here in Darwin loses power almost every day in the afternoon at this time of year (high amount of lightning strikes in the afternoon take out the grid) and then its the fun of suffering horrid heat with not even a fan for a few hours! haha...  Cheers again for your response I appreciate it!

[nothing to lose]

 That's a mighty nice one but not the one I was thinking of, glad to have that link again though.

 Windstuffnow had this one from copper tubing I was thinking of. Making it larger and using in a closed loop system I think it'd would nice and easy on solar.

[wdyasq]

http://www.zomeworks.com/tech/doubleplay/index.html

One of the authors is an enviro-nazi but that doesn't eman he has bad ideas, just some of his solutions are unworkable (not necessarily about this subject).

Ron

[ruddycrazy]

Hiya Storm Country,

                   Eh mate I'm situated up in the Adelaide hills where it can get pretty hot in summer and what I did to help cool the house was put in a shade house the full length on the north side. This alone dropped the inside temp in the house by 10 degrees and as my wife now uses it as a greenhouse I plan on setting up a retic system so on hot days I can spray a fine mist thru the shade house. This idea comes from the old faithfull kalgoolie fridge principle. As your up in the north of the country setting up some shade cloth around the house and spraying water force fanned around should help on the cooling side. I did something similar when I lived in port hedland and it worked great but I don't know how you'd go with all the humidity you have there but it won't cost a bomb to try it.

Cheers Ruddycrazy

[Aelric]

Yes I agree the NH3 version is good too.  Here is an article about a solar powered icemaker on homepower:

http://www.homepower.com/magazine/downloads_homebrews.cfm

just find the link for:

A Solar Ammonia Absorption Ice Maker         Article on making a solar ice maker. From HP #53, in Acrobat format.   

I had actually thought of using this design with antifreeze looped around the collection tank rather than water, then just run that to a radiator in my house and blow the air in.  With a solar powered motor to cover or expose the parabolic trough with a dark lid that was on a timer you could easily control the heat/cool cycles, thus making this run without need for human intervention.  Possibilities are endless :-)

He lists general plans and a full price breakdown, buying everything he used it came to $510.  Of course would be much cheaper if you had some parts yourself hehehe.  I thought about this one myself because the factory I work at scraps a lot of galvanized steel, would be easy to get ahold of enough to make a parabolic trough (we can buy scrap steel for 12 cents per LB <evil grin>) just hard to convince the wife, plus I get a bit nervous working with flammable/toxic gas.  Still might go that route but I plan on playing with metal hydrides first.  Yes I do agree that if it were outdoors as this one is that you could easily keep it safe, just have it out in the open with a hose handy just in case since NH3 is easily soluable in water.

[nothing to lose]

 Another thought in regaurds to my idea of making the unit raise and lower behind a shade pannel would be to build it as a daul unit to somewhat seesaw , as one side raises the other side lowers. It could be built as 2 units in 1. As one side is heating the other side is cooling. If building it as a 2 unit system then it could be balanced easily in the center. When I reffer to it as a 2 unit, I mean to complete units including two seperate cooling coils and freezer chambers. So one unit is boiling off amonia and cooling as the other unit is collecting amonia.

One of the reasons I really never got into this project I think is there are many Methe labs (illegal drugs) around our area. Unfortunatly they were using amonia alot I think to make the drugs, so with all my off the wall and weird projects I don't want to buy amonia and have everyone thinking I am making drugs.

 Otherwise I would probably been building one of these myself.

[nothing to lose]

Thanks for the link, that's one I saw before and been looking for.

15lbs ammonia. 21' of 3" black iron pipe. 10lbs ice melter salts. That's the part I think should be modified to pivot out of the heat. They say about 3/4 of the ammonia should evaporate off at 250F. At 15lbs for a full pipe that would be 11.25lbs less weight when the 3/4 ammonia is removed from the salts. I did not remember the length being 21' though, but that should be fairly easy modified, maybe shorter and wider?

 Perhaps 4 sections of 8' pipe for a total of 32' and use more ammonia and salts for more cooling in a cycle?

They say it takes about 3 hours of good sun for the generation cycle, then it could be shaded to start the freezing cycle. If making two units that pivot in a seesaw style into and out of the heat zone, then on a hot summer day one might expect 4 or more freezing cycles perhaps. Since the cold water would be needed for cooling a house durring the day mostly, then the cycling would be important.

One thing I do not see is how long the freezing cycle is supposed to take, when the pipe cools and the salts start absorbing the ammonia again, thus freezing the 10lbs water. Is this dependant on how fast the pipe cools, the tempature of the water in the freezer, the difference in temps between the two, etc...  That would make a difference in how many cycles one could expect also of course.

[Aelric]

My best guess on the length of the cooling cycle would be to add a pressure gauge and a thermometer or thermocoupler.  As I understand it the pressure builds as it goes to liquid state, then during cooling cycle it should loose pressure (I think) so if this is true maybe some sort of pressure switch could be installed to regulate when the cover extends to begin the cooling cycle maybe could be done automatically.  The more automation the better... could even make a air cond. maybe.  Just some ideas.

[Kwazai]

seems like it would be easier to hack one of the little rv refrigerators- using the peltier device instead of propane and blowing air thru the box.

just my .02$

Mike

[StormCountry]

Problem is the cooling per Watt is very low with peiltier modules.. so used by themselves they chew way too much power.  The average thermopile (commecially avail) draws around 4amps for a cooling surface of 4cm x 4cm and only cools that area to ambient sub 20c.  So really on the scale of things it wont compare to the cooling generated from vapour compression types..  The biggest challenge seems to not be boiling/compressing the NH3, but moreso controlling or phasing the cycles!  its brainstorm time..  Some awesome ideas raised already from some great minds in this thread!

[GCHurricane]

We've just been blown back into the Stone Age by a hurricane on the Gulf Coast USA. The most desirable items (aside from cigarettes and beer for many) were ice and a cool place to sleep.

I am pursuing a solar PV collector that can be erected upon demand, to drive a DC refridge. Another one for a DC ice maker. Another one for a DC window A/C unit to just cool a sleeping room.

During the recent unpleasantness, one item of good utility was a spring-wind AM/FM radio by Freeplay.org. I scanned their website a moment ago and saw the Freeplay Plus, exactly the one that sustained our info needs for more than two weeks of power blackout.

Don't believe how dependent we've become on readily available info. Roads were closed both physically and by edict of emergency responders. When and how to start back home was a mystery. Availability of fuel enroute to the storm-impacted area prompted porting 10Gal of gas to get out again if necessary.

So next time, all things must be in place to sustain life in some degree of comfort. Solar PV collectors are my answer, and small, low-consumption DC appliances are my interest. I have some collected data to share.

Anyone shoot holes in this idea? Counter-proposals?

GCHurricane

A Blast Into the Past

[Derek]

Being in the horticulture and greenhouse industry before, here is how they do cooling for large greenhouses.  They pass air over water moving through some materials to cool with evaporation.  Simply blowing air over a big chunk of ice would not only cool the air just because of the idea, but any evaporation that occurs would also lead to cooler air temps being passed along.

I too have been interested in this, but of course would first like to make such a thing on a smaller scale for cooling a single room in the house.  

What temperature does the ammonia have to reach in order for this to work then?

[segler]

Since I have no information about your house, I will try to give you information based on your climate.  Although I am an electronics tech and interested in technology, I have found that passive systems are the best investment.  They are low maintenance and comfortable. You will appreciate this later when you take vacations and the house takes care of itself.  You can always add active systems later as you have time and money.

I can relate to what GCHurricane told us. I have been through force 5 hurricanes and know them up close and personal.  Everyone should take this disaster as a lesson.  The historical construction in the U.S.A. and Canada has been stick frame wood buildings, even along the coast line.  In Mexico and the Southern parts of this hemisphere most homes are built with masonry just as in Europe and most of the world.  Today they use steel reinforced concrete.  Even the cheapest homes in Mexico are steel reinforced cinderblock.  They never have to worry about wind damage, although some of the homes are in the flood surge area.

Any house in Tropic areas should have high ceilings and double hung windows with screens and strong shutters to protect them in storms.  The best shutters I have seen are used in Europe of a all places.  They are a roll down aluminum shades that are built in to the house.

There should be a tower on top of the house that is centrally located or over the kitchen to create a vacuum that sucks the hot air out of the house, but can be closed by a srong shutter.  An attic fan can be used for a house that was built with low ceilings.  In your latitude a North facing porch should be used to shade the house, and the West side should have a wall or trees to shade the house in the afternoon sun.  Screened sleeping porches were used in the past, but porches should now be built from steel reinforced concrete columns and roofs to keep the lifting forces from tearing the roof off the house.

Decidous trees always help to shade, but can be a problem in high winds when they fall on the house.  Banyan trees are best for cooling if they will grow in your area, but they take a while to grow and grow very large. The first priority should be thick walls of stone, Concrete, Adobe, or thick stucco.  The color of the roof should be light colored and heavy, but reinforced to survive high winds and hail.  reinforced concrete with a concrete wash is good unless you have overhanging trees which would drop leaves and sap on it and promote growth of moss.

A Solar air conditioning system using an absoption refrigerant in your area should best use a trough type parabolic system that focuses on a tube type collector that is enclosed in a vacuum container such as a glass tube.  This would give a low profile to high winds, use minimal control systems, and would only have to be protected from hail.  If You reinforced the roof they could be mounted there and provide shading also.

For protection from hail you could use remote impact sensing panels on poles at the perimeters of your property to activate motors to turn the collectors upside down to protect them.  These sensors would be similar to antitheft tape on windows that sense an impact, just make sure you protect them from birds with a fishing line barrier.  The problem in your area is that the storms move so fast that the sensors and motors may not be able to respond fast enough.

There is another alterative, if your storms are similar to some others I have seen in Tropical areas.  There is normally a reversal of wind from a gentle morning land breeze that slacks at noon and then comes in from the coast rapidly around 3 to 4 PM as the humid air feeds the storm right before it reverses and the downdraft from the storm hits you. There is a low level cloud that precedes the thunderhead to the coast it will shade the collectors, and a photovoltaic sensor could turn the collectors over before the storm hits.

Ammonia's use as a refrigerant today is mainly for industrial sized units and consumer refrigerators for RV's, boats, and homes where electricity is unavailable.  It may be hard to find a unit for air conditioning a house.  Anhydrous ammonia's use as a refrigerant has gone out of favor due to the hazardous vapors. It's use is also now regulated in some countries due to its possible use as a chemical weapon by terrorists or the production of methamphetamine.  The last home A/C unit I saw was made by Servel which is now Dometic, and that was 20 years back.  Ammonia has been replace in absorption systems by AQUEOUS LITHIUM BROMIDE.

If you decide to use Ammonia the best way to deal with the hazardous vapours if it leaks is to use a heat exchange system to seperate the indoor heat exchange loop from the ammonia refrigerant loop which is kept outside.  The current cooling loops use a propylene glycol/water solution. This solution is also stored in insulated tanks to give cooling between day and night.  In your proposed Solar use, the stored solution would be used at night.  In commercial builings it is used to cool during the day, and the refrigeration units are run at night when the electricity is cheaper.

ETHYLENE GLYCOL IS NOT TO BE CONFUSED WITH PROPYLENE GLYCOL!!!  ETHYLENE GLYCOL IS NORMAL AUTOMOTIVE ANTIFREEZE AND WILL DESTROY YOUR LIVER AND KILL YOU IF INGESTED.  Propylene Glycol is used in food products like canned onion rings and to winterize RV water systems.

The mention of greenfreeze by Aelric is not relevant to your situation since this is a compressor refrigerant, and you need an absorption refrigerant for a solar system.  Propane and butane were used as a mechanical compressor type refrigerant in electric powered home refrigerators till the 50's or 60's and there are still many of these old refrigerators that are still working.  The problem with them is when they leak the flammable refrigerants.  This has confused many people recently since propane is burned to heat ammonia absorption refrigerators in RV's and Boats when shore power is unavailable.

Evaporative systems are best used in low humidity areas.  There are new systems that do not draw the humidified air in to the house, but use a heat exchanger to keep the indoor air seperated from the chilled and humidified air, but they may not be efficient in your area.

I wish you the best on your voyage in life

Will

[gonedrovin]

I spent a bit of time in Darwin & most of my life in North West QLD..so I know the heat.

A simpler solution may be to bury a hundred metres of HDPE pipe 2 or 3 metres underground, pump water through it to a second hand chilled water type Air con heat exchanger...3 metres down at Rockhampton the temp is a steady 19 degrees. You won't use much energy to move the water, for every litre you're lifting, another litre is falling. To move the air thru your heatexchanger, start with convection and maybe help along with a fan.

For the insensible load..the humidity, look around for some sort of solid desiccant dehumidification system. Munters, might be a good place to start. With a good volume airstream, at low pressures, through a big desiccant wheel you should easily be able, with a relatively cheap, homebuilt solar collector, to heat it enough to regenerate your desiccant.

Having read your comments about commercially available gear, I agree. Most homeowners today just want a system that is compact and won't clash with the B V & T.

But one thing most of us do have is space, and a low energy system, with big slow fans, moving air slowly thru wide bore ducting at low pressures will have far fewer energy losses, less noise, and less wear and tear. If you can't get enough cooling from the earth coupled system, maybe a 2 stage evaporation cooler might help, especially if you're using the desiccant dehumidification system.

The dehumidification is the key here, especially during the wet. My family lived at The Narrows, and the poor old aircon was working overtime to get the water out of the air.

[sahlein]

I plan to move to a high desert area in SoCal.

The thought crossed my mind to use cooling coils built into thick masonry walls and circulating a coolant through these coils at night.  I may use some kind of swamp cooler outside to take advantage of the cool night air and low humidity.

The really hot part of the day is from Noon until about 5PM.

The idea is to have enough "Thermal Mass", insulated of course, to get me through the really hot part of the day.... I could easily adjust to sleeping from Noon until 6PM.

In winter maybe I could use solar collection to heat my "heat-exchange medium".

Heat removal in summer would be for me, girlfriend and our dog.

If I had several thousand gallons of cooled "heat-exchange media" in the walls would it do any good to keep us cool during the hot part of the day???

We do not need much more than about 1000 square feet for the cottage which I want to build.

I want to be "semi-off grid" with wind and PV to help offset the electric bill.

I have recently retired early so I have time to do some building now.

Anyone have any input or ideas???

J.S

[rpcancun]

Which Desert?

Morongo/Yucca Valley area??

Is concrete a good choice in the eathquake state?