Would a climate battery work for cold cloudy climates?

The main reason "Forest Garden Greenhouse" cites for using perforated drain pipe is to use the phase change to your advantage, both ways.

When you're charging the battery, the warm moist air from the solar collector (your greenhouse)  drops both heat and moisture when it travels through the perf. pipe under the greenhouse.

This phase change allows for considerably more heat storage in the limited insulated area under the greenhouse.

Also, on the second half of the equation, when you take heat from the heat battery, the water that evaporates gives you the benefit of the phase change again, again maximizing the heat transfer ability of a certain size/mass and a certain fan/pipe capability.  He also claims the plants appreciate the lowered humidity in the summer and the raised humidity in the cold season.

Todd Parr wrote:According to the Geo-Air Technology A-Z publication, geo-air systems are vulnerable to Radon gas contamination if you use perforated pipe, but solid pipe acts as a barrier against it.  Also "I've seen NO water accumulations from condensation in any of our tests, and therefore the perforated drain pipe, and drain pipe with slits are a liability in many ways."  In areas with high water tables, solid pipe will block the infiltration of ground water into the tubes, although that is not a concern where I am.  They give other reasons for solid pipe as well, and are pretty adamant that only solid pipe be used.

I agree it is really important not to confuse the Climate Battery System which uses perforated plastic tubes with „Geothermal Heating Systems“ which use closed tube systems. The except that i have included below from John Cruickshank via eco systems design inc. explains the Climate Battery concept and why perforated tubes are „essential“ for it to function. Unless you are just into experimenting why re-invent the wheel? There is more than a decade of experience out there on both systems that you can read up on.

One of the big problems that occurred with „closed pipe“ geothermal heating systems that use (air) for heat transfer was and is „mold growth“ inside the tubes. For this reason the house building industry has moved away from „closed pipe - air systems“ and now uses closed loop „fluid“ systems usually in connection with heat pumps.

To gain more “Climate Battery” or earth battery to extend the heating capacity in winter you must go deeper and build layers of perforated tubes and earth. If this is economically practical is another question. For this reason auxiliary heating sources like wood or pellet stoves are generally used as an alternative solution.

Climate Battery Functions
http://www.ecosystems-design.com/climate-batteries.html

The magic of phase change from liquid to vapor and back again drives the Climate Battery™, or Subterranean Heating and Cooling System (SHCS).  The system functions like a simple refrigeration system, moving heat from one place to another. But a typical 1200 square foot greenhouse needs only the equivalent equipment and running costs of a single large household refrigerator!

By slowly circulating all of the hot, moist daytime air of the greenhouse down underground where it is always cooler than the greenhouse air, the Climate Battery forces the vapor to condense. By doing so, the solar heat as well as the chemical heat from the plant photosynthesis that was required to evaporate the moisture in the first place is forced into the soil. The "miracle" is that by inducing temperature change over the phase change barrier we have the potential to harness 5 times the energy normally the case if we simply tried to solar heat objects cluttering up your precious greenhouse floor space. And by inducing this "dewpoint" condition in the soil of the greenhouse, the plant roots are always being bathed in warm, moist conditions - the perfect balance for plants and solar greenhouses. The space is heated by the massive amount of radiating solar heat stored in the soil under the greenhouse, and with fans to circulate cooler nighttime greenhouse air through the tubing network, adding warmth and moisture back to the greenhouse.  

Davide Honey wrote:

Todd Parr wrote:According to the Geo-Air Technology A-Z publication, geo-air systems are vulnerable to Radon gas contamination if you use perforated pipe, but solid pipe acts as a barrier against it.  Also "I've seen NO water accumulations from condensation in any of our tests, and therefore the perforated drain pipe, and drain pipe with slits are a liability in many ways."  In areas with high water tables, solid pipe will block the infiltration of ground water into the tubes, although that is not a concern where I am.  They give other reasons for solid pipe as well, and are pretty adamant that only solid pipe be used.

I agree it is really important not to confuse the Climate Battery System which uses perforated plastic tubes with „Geothermal Heating Systems“ which use closed tube systems. The except that i have included below from John Cruickshank via eco systems design inc. explains the Climate Battery concept and why perforated tubes are „essential“ for it to function. Unless you are just into experimenting why re-invent the wheel? There is more than a decade of experience out there on both systems that you can read up on.

One of the big problems that occurred with „closed pipe“ geothermal heating systems that use (air) for heat transfer was and is „mold growth“ inside the tubes. For this reason the house building industry has moved away from „closed pipe - air systems“ and now uses closed loop „fluid“ systems usually in connection with heat pumps.

To gain more “Climate Battery” or earth battery to extend the heating capacity in winter you must go deeper and build layers of perforated tubes and earth. If this is economically practical is another question. For this reason auxiliary heating sources like wood or pellet stoves are generally used as an alternative solution.

The system that I am talking about is not a climate battery system, and it is not a closed tube system.  The tubes are open at both ends and are simply using the constant temperature of the earth to heat and cool, as necessary.  With these systems, there is no mold growth within the system.

Todd Parr wrote:

"The system that I am talking about is not a climate battery system, and it is not a closed tube system.  The tubes are open at both ends and are simply using the constant temperature of the earth to heat and cool, as necessary.  With these systems, there is no mold growth within the system".


By "closed tube system" I meant "non perforated tubes" but open at both ends like you are suggesting. Because this type of system requires an adaquate length of pipe for the heat exchange to occurr, condensation from the air will remain inside the pipe especially in summer. This eventually leads to the mold growth problem i was speaking about.

henry Trott wrote:Thanks
    Soooo much new information coming out in the last months it seems. If you have time I'd appreciate you taking a look at what I have done. I don't have a lot of funds for this venture, but look forward to increased food production, even from this little greenhouse if I get it somewhere near right. Paradise

Very impressive! Please update the blog. I subscribed.

Davide Honey wrote:
Because this type of system requires an adaquate length of pipe for the heat exchange to occurr, condensation from the air will remain inside the pipe especially in summer. This eventually leads to the mold growth problem i was speaking about.

The Greencube people have built these systems all over the world and done extensive testing over many years and have not found that to be the case.  Regardless, I'll know soon enough first-hand, because that is the type system I am building.

Other groups and individuals who have built these systems have had differing experiences.  Those experiences are valid.  I've been researching this subject for several years myself, preparing for our home build in Michigan.  The literature is thoroughly divided on the issue of condensation in the pipes and mold therein.  No consensus on the extent of the problem and more than one approach to dealing with it where it is seen as an issue.

One thing I don't see being addressed is the emphasis Hait placed on stopping the flow of water through the area where you are trying to store energy, because water does such a great job of absorbing and transporting heat energy.  His designs focused on doing a sheltered "umbrella" surrounding the house, with a waterproof layer above the tubes, then insulation, then the tubes.  This protected the area with the tubes, allowing improved heat storage.  One of Hait's designs worked well enough to maintain constant temperatures around 68F year round in Montana.  It works.

Jerome Osentowski is growing tropical plants at 7200 feet using similar technology (distinctions among "PAHS", "Climate Battery", etc. are more branding than anything substantive).

There's lots of experience showing that these systems work, and lots of differing experience in details, such as the mold issue. It is a possible complication to be aware of and to have plans for addressing should it arise.

Hi everyone

I know this is about climate batteries and I admit I dont know much about the concept. It also seems to revolve around trying to heat the greenhouse in general and while I know even less about that, I watch a lot of YouTube and every blue moon I find something that peeks my interest. At the beginning there was talk about insulating the north facing wall and it reminded me of a video I had seen. Maybe not even close to what you are looking for but what the heck, I wasn't looking for it either til I found it. Give it a watch and who knows........ Just a thought.  If this is way off base, please accept my apologies.

Hi guys.

I'll chime in with my 2c's worth.

I'm in a similar situation as you are.
I'll start building my house + greenhouse this spring (house first).
But if i dig for foundations i would be better off to dig for everything, including the tubing for let's call it "temperature mitigation".
I want to use some tubes for the greenhouse and some for the house.
They will be used all year but i suspect more during winter.

As such, i realized, just as Todd did, that an external system is much better (due to costs and type of climate).

Now, for the physics part.
Remember, any warm, moist air, will condense if cooled below it's dewpoint.
Such a scenario is guaranteed to happen if pumping outside or greenhouse air during warm parts of the year (summer).
So, there will be some water in the underground pipes during these times.
The only question now is what to do with it.
I've seen people sloping unperforated the pipes 1/10 to a low spot with a drainage hole (or more holes), all underground.
That low spot can be a dry well or a smaller cavity filled with sand / rubble.
I've seen people using perforated pipe (preferably just on the lower side of the tubes) so any condensation will drain right at the spot it's formed.

Pros and cons ?
As Peter said, things are highly debated as not all experiments were done in identical conditions.
However, there are some points to note.

	Pros	Cons
Perforated	Water will drain at the spot	Radon, if present, can infiltrate
		Unusable if there's a high water table
Nonperforated	No way for Radon to get in	Pipes must be sloped so condensation can drain to a dry well

Debating mold, it's been said that, at least for perforated pipes, there's no mold because of competition between mold bacteria and earth bacteria.
This may be true if the tubes are close to organic soil layers but i don't think there's enough of it deep under but that might not be an issue.

All in all, i would use perforated tubing because water will just go away.
My issue is i can't easily find tubes with perforations just on the bottom 120 degrees or less.

Joseph Johnson wrote:Hi everyone

...

Good video.  I may need to figure out a way to incorporate it.

Hi Joseph, I saw that video a while back when researching compost heat.  I know it doesn't relate to the official thread but that is actually my plan for heat (see quote below).

Mike Jay wrote:R2 glazing on south side of A frame
R40 straw bale insulation on sides and North side
Entry vestibule
Shallow frost protected footing for ground insulation
Compost inside greenhouse for additional heat generation
Water barrels for thermal mass
Phase change materials to act as heat battery

I may have understated it a bit in the quote but behind solar gain, I'm planning on compost as my main heat generation.  For anyone that's interested, Gaelan Brown's Compost Powered Water Heater is a tremendously helpful book.

I just redesigned my greenhouse again yesterday (iteration #15).  One of these days I'll put the plans on here for review, but I want to get my ducks in a row first...

I have some experience with SHCS greenhouses in the Colorado foothills (8300'), we have two of them. The smaller one was built on the S side of our basement of the main house, it is 8'x18' and uses the attached garage (other side of N wall) as a heat sink as well as the soil in its raised beds. That GH generally remains above freezing without any supplemental heat, and warm weather plants (tomatoes, peppers, etc) will grow year round (although they do slow down considerably in Dec-Jan due to lower light levels).

The larger one is 16' x 34' and on the S side of an uninsulated barn. It has a full SHCS in the subsoil under the GH area. It does however require supplemental heating in the winter to keep it above freezing, and does need to vent excess heat in the summer. This GH is not yet finished (still need insulation on the N wall and I want to experiment with higher volume fan in the underground system), but is performing about as expected. John C used to say that with just a SHCS system you can expect roughly a month extension on each end of the growing season in Colorado for a larger GH. And that is pretty much what I am seeing even without the N wall insulation or additional heat on the bigger one.

For smaller GH's and ones which are connected to other conditioned spaces which can be used as a heat sink, you can likely get freeze free operation or close to it. I have in my smaller GH for ~15 yrs now. I have not run the numbers, so I can't say how much of the smaller GH's success is due to the availability of an insulated garage to use as a heat sink, and how much is just the difference in size ratios of heat loss in the GH itself. There are also differences in that the smaller GH has an insulated knee wall while the larger one is glazed to the ground.

While it would be nice to capture every BTU of excess heat in the summer, and be able to pull it all back out in the winter when temps plunge, that is not realistic (at least for my climate needs). One can get real heat savings from a SHCS but in a ag zone 5 GH it just isn't going to be totally heat self sufficient all winter; maybe with interior covers and for greens but not for warmer climate plants (tomatoes, citrus, etc). The subsoil system just cannot absorb heat fast enough to take in all the excess on a sunny warm day. Yes there is a 30F drop in temp between the air going in and the air coming out on a hot day, but that does not cool the GH sufficiently to keep it from overheating without additional ventilation (we get a lot of sun), which is pretty much the expectation that John C and SHCS sets. And when it is below 0F outside the air coming out of the SHCS tubes from underground is warmer but it can't pull heat out fast enough to keep the GH at growing temps, at least not through the entire winter here. In other climates you will likely see different results.

The other thing which all passive heat storage system have working against them is their efficiency decreases as it is used. It is very efficient putting extra heat into the soil (or water barrels, etc) when they are empty of heat and cool. However as they warm up that heat transfer becomes less and less efficient as their temp rises closer to the hot air you are trying to pull the heat out of. Similarly taking the heat back out is easiest when the heat store is warmest, and becomes less efficient as the heat store cools off (sadly like in Jan when you need it most).  You can adjust for this somewhat, by having a smaller heat storage mass with a higher surface to volume ratio. That will allow it to heat up faster and cool off faster. It might be good for a single day's heat needs, but obviously would not do much good for a prolonged cold cloudy period. Perhaps a system with multiple heat stores, some for quick exchange and others for longer term would even things out some.  

Anyway, FWIW, those are my thoughts/experience on this...

Steve, thanks, that is good info.

Thanks Steve!  I do think you get a fair bit more sun than Todd and I in the winter.  Must be nice.....

Mike Jay wrote:Thanks Steve!  I do think you get a fair bit more sun than Todd and I in the winter.  Must be nice.....

One of the many reasons I want to move back to Colorado...

Todd Parr wrote: Also "I've seen NO water accumulations from condensation in any of our tests, and therefore the perforated drain pipe, and drain pipe with slits are a liability in many ways."  

thats weird since the developers of these climate battery systems generally say that the major energy exchange is from phase change of water from vapor to liquid and vice versa

RE: condensation in the air pipes

I have never dug mine up to check but I still think it is likely good insurance to put in the vented/slotted black pipe. There should be condensation down there if the warm air in your GH is humid and the soil down there is cool. At least in the spring after a cold winter. Be interesting to hear if those that reported dry tubes checked then.

But even if there isn't condensation moisture, you might have underground leaks. If you ever have a wet season and the water table rises to or above the level of the tubes, it is likely that some of that water will find a joint and make its way into your tubes. If you have solid tubing how is that water going to exit when the water table goes back down? For that reason alone I would use the vented/slit tubing.

I have heard reports that the sock over the slit tubing is unnecessary; that dug up SHCS systems that did not use it did not have sand or soil in the tubes. Although I don't recall hearing what soil type was around those tubes. So it might still be a good idea to use the socks. The difference in cost is minimal.

Steve Sherman wrote:RE: condensation in the air pipes

I have never dug mine up to check but I still think it is likely good insurance to put in the vented/slotted black pipe. There should be condensation down there if the warm air in your GH is humid and the soil down there is cool. At least in the spring after a cold winter. Be interesting to hear if those that reported dry tubes checked then.

But even if there isn't condensation moisture, you might have underground leaks. If you ever have a wet season and the water table rises to or above the level of the tubes, it is likely that some of that water will find a joint and make its way into your tubes. If you have solid tubing how is that water going to exit when the water table goes back down? For that reason alone I would use the vented/slit tubing.

I have heard reports that the sock over the slit tubing is unnecessary; that dug up SHCS systems that did not use it did not have sand or soil in the tubes. Although I don't recall hearing what soil type was around those tubes. So it might still be a good idea to use the socks. The difference in cost is minimal.

High ground water is one of the reasons NOT to use perforated pipe.  You are worried about a leak, so you put in pipe with holes in it to ensure you have a leak?  

Todd, whether you use perf pipe or solid there WILL be ways for water to enter the pipes. An accidental cut or manufacturing defect in the pipe, any couplings you used to join pieces of pipe together, the joints with the manifolds, condensation, etc, etc. In spite of how careful we might try to be (and you should be careful, don't get me wrong), there will be water in the pipes when the ground water level puts them under water. Maybe not the first year or second, but eventually.

For me the question is really what's going to happen with that water once it is in there. That's why I chose the perf pipe, I wanted an exit for that water other than having to evaporate it out.

I am assuming that high ground water is not a common thing in your GH location. If it is, then in all likelyhood any SHCS or Climate battery is going to fail, because that high ground water will move carrying away heat. Certainly you don't want to be putting stored heat into that soil if there is water flowing underground through it, cause that heat won't be around for long.

In regards to radon, I think you are right, that perf tubing will allow more of it into the GH air. But my experience is that any GH build over high radon producing soils will tend to have high radon levels in their air. Unless you don't have any exposed ground in your GH (concrete floor), and the flooring is well sealed. If you are going to have ground beds, I'm not sure how much diff the heat exchange tubes going thru the soil will make (but I admit I have not measured it).

If I were in a high ground water area, I probably wouldn't consider this system at all.  If I were going to try this in a high ground water area, I would have to defer to the people whose research I have read, and they say to use solid pipe.  You may be right that you are going to get a leak at some point, but if ground water level puts the pipes under water, and use are using perforated pipe, I would assume they would fill entirely with water and burn out your fan trying to circulate air through a closed pipe.

As I have said in this thread a number of times, the system I am building is not a climate battery system, so that part isn't relevant to my situation, and I don't feel qualified to speak on it.

Since we had a warm spell this week I bought a new tool and decided to do some soil temp research.  Per the only ground temperature map I can find (BuilditSolar) it suggests that my deep soil temps should be around 42 degrees.

My sand point well is an unknown depth but I'm guessing 15-20' underground.  My well water comes in at 49 degrees (much higher than I expected).

The new tool I bought is an adjustable hole auger (Seymour AUA2 Auger) after watching a youtube video of a guy digging a well with one.  I was a bit worried about the dirt falling out of it due to my sandy soil.  It was not an issue at all.

I had a spare 4' length of 3/4" black pipe so I could extend the auger to 7.5' long.  If I was better prepared I'd've had another 10' length and another coupling so I could go deeper.  I just kicked aside the 12" of snow and started digging due to no frost

I found my ground temps to be:
0'      36F
1'      36F
2'      38F
3'      36F (seems like a bad reading)
4'      41F
5'      43F
6'      43F
7'      44F
7.5'   45F

If my well is 15 feet deep, 49 degrees for that water seems totally reasonable when compared to these temps.  

Long story short, if you're considering the system Todd is describing (using the earth to warm greenhouse air - NOT to store excess greenhouse heat) you may want to get an auger and dig a test hole in the dead of winter now to see what actual temps your ground gets to in January.

Hello,

My first post here. I am 100% amateur, just fan into greenhouses, yet, I did not have any (well I am having first one, but its only 1m2). But I am so excited about this idea, that I am googling hours and days to get more info
Here are my thoughts:
Like every building, also the greenhouse has some heat loss, during day and night. How much of a heat loss is 55F difference, I am not sure. Example: outside 0F, inside 55F, and the main factor is the lambda of the foil/glass or R value.. In different words, how much heat we capture, or let thru/out.
Imagine if our greenhouse would be built only from 2 glasses, between which, there would be vacuum. We would have close to zero heat loss, therefore one tea candle would keep up the heat at desired 55F (ground temp)
But thats impossbile, as there is no glass like that, and even if we use regular glasses, it would be extremely expensive (maybe $15/sq ft , but the Uw=1 or so, so heat loss would be very high still.
Perhaps, as mentioned, a movable insulation (2' of some good wool/EPS), but not sure how to handle sunrise/sunset temp shocks / heat gain=loss shocks.


Regarding radon, I think it behaves like gas - it simply escapes from greenhouse, unless its 100% airtight.. I think it should escape thru regular foil (even two or three or more), but not sure about window.. But any gap in greenhouse = heat loss, hm.

But back to the topic, so we have some heat loss value, so we need to match it with heat gain. There is no battery, which would match it for whole winter, because it is impossible to insulate the battery itself. We could pack/insulate the battery underground or even above ground with 5' wool/EPS, but the heat will be lost after few days, or weeks at most, IN MY opinion. No technology can catch heat forever, nor for month. it would need to be MASSIVE, and the problem is - IS the heat gain during day/summer/sunshine high enough, to store such energy? I have no idea. Just thinking aloud.

The good thing is, there is 40-50F underground, "for free". But still, rain = heat loss, wind = heat loss.. lack of insulation = heat loss.

Thats why I am googling days around, if there is a true and existing greenhouse with data during winter, eg in +-NY area (my place is Slovakia, Europe).

The cost is one thing, but it SHOULD be one time investment, so if it pays off in 10 years, it is quite interesting (its not liquid asset I am afraid, so no house selling in near future?)

I am not able to calculate  the loss with much accuracy... Maybe someone is?

For me - amateur, its easier to simply build some 2-10m2 and test it
The more passive, the better, the less on/off mechanical switches the better. I can not believe its not all around us already... "Free" food basically

Also, what about mirrors, mylar ? Few sq ft of extra nondirect sunlight... Or what about rocks as thermal storage?
http://www.engineeringtoolbox.com/sensible-heat-storage-d_1217.html

But I am afraid, none of this alone is able to generate passive 365.25 days greenhouse.And combining them = too complicated, easier and cheaper just to turn on the heater and bear the costs.. (because the time I would need to monitor it is "expensive" but I never calculate this into costs, but imagine one day the system fails, and all veggies will go to compost, that would hurt too...)

Anyway, thanks for great forum, so much new information for me

Dusan Tomasek wrote:
I am not able to calculate  the loss with much accuracy... Maybe someone is?

The math I use for conductive heat loss is :  Heat Loss (Q) in BTU/hr = 1/Rvalue * area * delta T
For infiltration (leak) loss it is: Q= delta T * Vol * Air Changes per Hour * .018

Temps are in Fahrenheit

The math challenge I have is the uninsulated floor.  If the soil is 45 degrees and I'm desiring a 55 degree greenhouse, how do I calculate that loss?  If the R value is nearly zero, then I get a huge loss even though the delta T is small.  Unless someone knows the R value of dirt.  Let's pretend it's a .25R per inch, should I say that I have 5' of dirt insulation?  In that case it is a R15 and there's basically no heat loss to the ground when you do the math.  So far I've just pretended the ground has an R value of 2.

Welcome to Permies!

I spent a lot of time last winter designing a greenhouse that I planned on building this summer.  Getting chickens and other projects got in the way so I'll continue the design this winter and hopefully build next summer.  

I just came up with another question related to this topic so I figured I'd put it in this thread.

I've seen many mentions of the great benefits of the phase change when warm humid air enters underground pipes, condenses out liquid and gives off a lot of heat in the process.

Maybe a physicist needs to chime in here, but I thought the only phase change points for water are the freezing point and the boiling point.  Isn't condensation just a conversion from water vapor to liquid water at the dew point?  

So is that really a "phase change" and are we sure that it transfers as much heat as a 32F phase change?

I have had success with a "greenhouse within a greenhouse" on a small scale and seen it on a larger (small commercial) scale. That being said, I am playing slow pitch softball in the Pacific NW compared to you guys in the northern midwest.

Just posting to subscribe, thank you everyone who has contributed. @Mike Jay, have you ever posted your greenhouse plans? I'd love to review as I only have 2 months to finalize my own plans before building.

Hi Mario, I haven't posted my plans yet but the design is nearly done.  I'll make a new thread (or several) for it when I'm ready.  Hopefully in January I'll get it done :)

FYI, when you find a thread you want to subscribe to, you can click the "Watch" button at the top and you should get notifications for it.

Regarding the heat released when water condenses in the underground pipes, yes, the amount of heat released depends only on the amount of water that condenses, not the temperature per se. The heat released for a given amount of water is called the latent heat or enthalpy.  The value is a constant for the type of fluid.

These systems work much like the heat pump we have for our house. It seems like a great idea and I am very interested in hearing about how the systems are working in practice.

I wonder if the greenhouse must be of a certain size to have enough thermal mass in the soil and length of pipe to be effective.  Ostenkowski's successful example in Colorado was quite large, 72 by 26 feet.

Hello,
I am reading this thread, and am definitely not an expert.
I just finished building our house in Poland and believe we have a relatively high water table in this area.
I thought the solution was simple: to use non perforated pipes, but then i stumbled on this thread

I was thinking directly, what if I use non perforated pipes, but i slope the pipes 2 degrees so that the water drains to 1 side.
Then the manifold ( or to the larger pipe) which takes the air up again i also slope so that the water is also collected in the side going up, then i can easily drop a small pump in every now and then to drain it.

Seems like a solution, or am I underthinking the issue?

Regards
Reinier