How To Design A Climate Battery for a Greenhouse
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- Опубликовано: 2 окт 2024
- In this video we will review how a climate battery, also known as a subterranean heating and cooling system works. There are a lot of misunderstandings on how to design and build one of these systems so first we will cover the basic theory behind them.
When designing one of these systems it is critical to understand how air moves through a duct system, why it is important to size it and how to go about doing this.
If you are looking to design one of these systems for your greenhouse you might find that this tool makes it a lot easier. You can purchase the tool at:
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In less than 10 years, Rob & Michelle Avis left Calgary’s oil fields and retooled his engineering career to help clients and students design integrated systems for shelter, energy, water, waste and food, all while supporting local economy and regenerating the land. He’s now leading the next wave of permaculture education, teaching career-changing professionals to become eco-entrepreneurs with successful regenerative businesses. Learn more and connect with Rob & Michelle at vergepermacult...
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I am working on a new greenhouse with an 18" below grade excavation in which that soil becomes part of the exterior grading. Instead of trying to push hot humid air down through tubes I believe it will be more efficient to push cold air up . Warm air will be gradually lowered due to density stratification resulting in a much more efficient heat exchanger. In effect the entire surface area of the excavation becomes the exchanger without resistance and cost of tubes. Thank you for posting your ideas.
Rob, Would you please mention the size of the green house you are building and the cost related. Thank you!
I think cfm can cool too quickly if the volume is turned over to quick. Wicking heat rate from ground is key ie surface area.
I certainly agree that pumping heat into the root zone of plants is very beneficial in the winter. Soil temperature is just as important as air temperature for optimal growing conditions. I do wonder why you would ever pull heat from the root zone in winter. It seems to me that should be a one-way transfer for successful plant growth. Earth tubes are proven to effectively heat the air of a greenhouse. But those earth tubes should not be pulling heat from the soil plants are growing in. Am I wrong?
Thanks for a great series of videos. Have you ever designed a climate battery using water in drums underground? Clearly there are some logistical issues, but water stores much more heat than gravel or soil.
I am in the process of building a thermal mass battery under my greenhouse, using a small swimming pool (8ft dia x 3 ft deep), five feet down...I am going to do experiments on growing produce year-round in extremely hostile environments...(our winters have seen temperatures as low as 30 below zero F...there is very little water...at an elevation over 5000 ft.)...I'll let you know how it goes...
If you get an hour of sun on a winter day your water may only gain a few tenths of a degree. With soil, the heat stays at around the same temperature as it arrived. The heat also remains close to the tubing where it can be recovered for use later that day. The conductivity and diffusivity of soil more than makes up for its lower specific heat capacity.
@@JohnGuest45 I believe that using a stone based thermal mass is more effective than soil and easier to use and maintain than water based storage. River stone has been used effectively because large voids allow passage of air easily creating uniform heating which is better that having hot zones in the soil. Stones allow for drainage and control of condensation, stones self compact which is important if your in clay.
@@capeguy
Even heating can also be described as dilution. This can be an issue when the system is operating "hand to mouth" where the heat in the mass is low (late winter) and all the available heat from the day is used the same night. A kettle full of hot water is more useful than a cold swimming pool that has a kettle of hot water added to it. When soil is used as mass, the heat remains relatively concentrated and within reach of the tubes. The best choice depends mostly on the local climate and especially the amount of winter sun.
@@shawnncheriyoung3597 i am wondering how it went if you can share
I am experimenting with very low budget build. Something I have not tested but I am curious about maybe you can help me. I would think blowing the hot air into the ground in the day and then sucking it out at night would produce more heat? I’m also curious on maximum air flow during the day and maybe half as much at night?
I keep hearing people use skepticism when talking about this process. I am curious how it could not work. It may not provide enough cooling for the building you put it in due to size mismatch. But unless someone can explain to me the physics of how the air could not be cooler after going deep enough underground for a long enough time, I am listening. It seems like the only reasons it would not work would be bad engineering or crappy installation.
do you think it is worthwhile to insulate the perimeter of the greenhouse underground where the pipes pass?
it was great
Does this work for house heating and cooling?
or at least cooling
I'm amazed there aren't formal studies on these types of systems yet. What would it take to make it happen?
To quote Professor Farnsworth of Futurama: "...dump trucks of flaming grant money!" :-)
Stop voting for rich politics. Boycott all Govermonts
Get an education and begin your studies
Not true, this is geothermal energy, who was invented in Italy.
@@BurninVinyl the word you needed was "discovered". No one "invented" geothermal energy. Also, No, this is not "geothermal energy". Related, not the same things.
Rob, you distinguish this system from annualized storage (I'm assuming you're referring to Jon Hait's work and Passive annualized Heat Storage) . Could you please explain what you see as being the differences? Because other than details in methodology, I'm lost on what distinguishes them.
wondering what sort of fan you're using to move the air.
The most important question is how much air is being moved.
You're an amazing person! Thanks for sharing this great knowledge. Curious, would it not benefit the "soil" to be small gravel and pebble instead? By replacing soil directly on the piping, wouldnt it hold underground temp better if it were stone? Any downside to this thought process?
underground stone/rock baffins for a rocket mass heater would benefit greatly from a packed sand then pebble floor above it, the heated air would leave the RMH exhaust and seep through the floor into the greenhouse also heating a mass that would in turn release its heat during the night/cooler times
you can have just a rock box under the home (large and medium rocks) that takes hot air from the attic with a fan in the day, and at night a vent flap opens into the house and closes off the outside air vent. Air flows over the rocks, rocks hold thermal energy, and at night keeps the home warm. A hot air solar collector can be used in combination with this idea to create an effective night time heating solution.
why not just use water in an insulated tank? that way, u dont have to dig underground. additionally, water can hold 5x as much heat than soil.
🤔Interesting.... are you referring to a hydronic heating type of setup or, rather, moving the air through the tank to heat it up. It kind of sounds like either would work (in my mind). I am a complete novice, so forgive me if my question seems offputting....
You would still have to put the tank underground...the point of putting the tank (or coils or pipes or blah, blah, blah) is to utilize the cool earth in summer and warm earth in winter...an insulated tank above ground would have to be heated or cooled...a tank under the ground is being heated and cooled by the earth...I am doing both; I am putting an 8ft dia x 3ft deep pool under the greenhouse. This will draw the cool from the earth in summer (vent tubes in the water will help)...in the winter the water will be kept warm by the earth...I will be using a rocket stove/mass heater (circulating the water through the stove, also) to add supplemental heat on the extremely cold days...
Great share, Will this be able to climatize a Mediterranean climate greenhouse? Where winter is cold (down to around zero Celsius) and hot summers up to 40 degrees Celsius.
The greenhouse we are thinking to build has double glazing on the south and insulated walls on the north. Considering a Trombe wall at the back wall, as well shade cloths on the outside with ventilation vents at the lowest south side and autogas vents at the highest north side, plus 2 large doors at east and west.
This kind of knowledge on passive climatizing is rare here so hoping to overcome the lack of local knowledge and examples by relying on info that I inquired in the last 10 years of Permaculture design and research and a great community of spread out international colleagues like you. Then provide this example to locals.
I’m open to any advice in any direction. The goal is to be able to stay inside and grow plants all year round in soil an aquaponics systems. The greenhouse is not attached to a home, it’s stand-alone.
Geo-location: 31.706334, 35.228147
Thanks in advance.
Oh hell yeah. I was in the young gardens conference and afterwards realized I’ve been subscribed to your newsletter for years! That webinar I watched really made me appreciate your work and congratulations on your successes! I’m happy to hear someone from same province is doing so well and creating good life in this climate!
where can i buy plans?
I going to build a greenhouse and would like help designing a GAHT system. Specifically, wait materials should I use for a 10’ by 20’ space. Size of fan and pipe
Check out our online course on greenhouse design. You can take our free 30 minute program here to see if it is a fit. www.smallfarmacademy.com/a/10115/LAFiALDo
Spend your cash on the tubing and fan, not shcs calculators that are available for free;)
www.ecosystems-design.com/climate-battery-calculator.html
JohnGuest45 thanks John 🙏🏻. I’m in Southern California and my needs are more for cooling have you seen any data focused on cooling. Thanks
@@caseG80
For a cooling bias the best approach is to install the tubing outside the greenhouse if space allows. The heat transferred during the day will be lost at night passively as its not insulated or sheltered. You can also do this with a standard under greenhouse installation by rerouting the inlet and outlet outside and drive cooler night air through the system to dump the heat. This increases the cooling capacity for the following day but does require power to run the fan.
I have been experimenting (on paper) with different designs that use water, instead of just ground, as a medium for heat storage. I like this idea because water has a high thermal mass and ought to be able to store a good bit of heat. The major downside would the cost of creating a reservoir vs free dirt, but I plan to need a reservoir for aquaponics anyways. I would love to know your opinion on this since you have put so much thought into solar and geothermal systems.
I have thought about this system too. the best result I have come up with is a combination of a segmented pathways of water, and one or two reservoirs. the reservoirs aren't too expensive as second hand water heaters can be pretty cheap, and are really well insulated.
the main design I came up with was a controlled series of switches that open and shut valves to different parts of the system (some holding hot water, some cool)
there need to be many different places to dissipate and increase the waters heat (exposed pipes and so on) because relying on the soil is not enough and the soil will overheat and loose all the thermal regulation benefits.
with enough pipes and thought the system could easily heat a house
People do this with barrels.
I wonder why you need the pipes to move the air. Would a manifold at each end of a rock bed of sufficient depth achieve the necessary contact between the moving air and the thermal mass( rocks of the proper size). I am guessing solid rock is way more dense than soil so the total storage per cubic ft of rocks would be higher than a cubic ft of soil.
I've thought of that too. The rock bed could be as deep as you want.
The heat capacity of soil increases with moisture content. A rockbed has a lot of air spaces which equates to less mass. The specific heat capacity of rock and dry soil are about the same per lb. Soil is generally free and available on site.
I was interested in the greenhouse design tool, but The Small Farm academy link takes me to a page where I can sign in (if I'm an existing user), but I can't sign up. Browsed around the small farm url and could not find anywhere to create a login.
In Colorado Zone 5b, GAHT systems are $9 / sq ft matched to east-west shed style thermal greenhouses.
i have a friend in construction and when installing in floor heating he would put styrofoam insulation on the ground so that the heat would heat the floor and not the ground. If the pipes are 6-8 feet down and you lined the base with foam insulation would it be more beneficial in that you would only be heating the ground above the pipes? looking to start construction in the spring and want to make it as efficient as possible.
What an amazing video. Can't believe it doesn't get more views these days regarding what our ignoration of sustainable, decentral energy management could mean one day.
do you think there is a way to do this with no fans? Making a closed loop solar chimney using well placed thermal mass...
I could find no way to buy the tool without logging in And I could find no link to create an account so that I could login.
so, why would an air particle choose to pass through the center of the pipe system when there are twice as many corners to overcome? Only if the outtermost side pipes were 'full'? If I'm an air particle and I'm going to take one of the middle pipes, I have to turn 90 degrees into the manifold, 90 degrees after the manifold, 90 degrees into a small pipe, then 90 degrees into the outter manifold, and 90 degrees again to get into the exit pipe. The air particles who go through the outtermost pipes have two less corners to overcome. I imagine someone's thought about this already and it was still deemed appropriate to have the middle pipes? Has anyone built one of this with softer corners for easier airflow? I bet traditional masonry heater builders would have some wisdom about design possibilities for these kinds of fluid air dynamics....
You gave me a good chuckle... thanks.
Good morning,
Summary: Will your model address the concerns I have listed out ? If so, it seems a small cost to be able to KNOW prior to construction the the earth tube system was designed correctly for the above ground construction (and to be able to play "what if's" for that).
Since you are in Canada, even though I see / hear the model input "for your US climate zone", you state your model is designed for cold climates. I am in US Zone 6b, Southern MO, it is rare for freeze line to extend 6" down. Is your model still accurate this far South ?
We are at the design phase, looking at earth sheltered (North wall semi-underground and bermed up to top of 10' wall etc.) using 'earth bank' system for primary heating, would prefer to avoid the need for a secondary heat system to maintain temperatures above 33 F., with thermal pane glass (we have source of 1" commercial thermal pane glass at LOW cost, even if structural costs will increase due to additional weight).
Summer cooling is of at least as much importance as is winter heating.
Is this a good tool, that using references for r values etc. (are they referenced or linked, or will we need to look up each ?) for different glazing / insulation questions (what is the effect on minimum temperature if we increase the exterior closed cell insulation on the outside of a 8" poured concrete wall from 2" to 3") type questions ?
I am aware of the 5 volumes per hour minimum winter but thought that 20 volume changes per hour would be more ideal for summer cooling - is there a rule or is this in the model to determine run time ? Is it better to run close to continuous or is it fine to have a 20% duty cycle ? If time the fan's are on is not a design criteria, then higher volume fan's with the ability to meet / exceed 20 volume changes per hour running full time make a winter heating / summer cooling simple - just differential thermostats controlling larger fan's.
Placing a bi-level set of earth tubes placed 3' and 18" down (staggered vertically and input diagonally opposite outflow), but I can clearly see the advantages of more accurate calculations!!! (is 18 and 36" for THIS climate adequate, or do I need to be 24 and 48" (does your model consider depth placement ?), AND your info was the first time I encountered the idea of 3 levels of earth tubes. I had also been planning to use smooth walled tube for drops, raises, manifolds for less friction losses, and the corrugated standard = lower cost 4" sewage drainage tubes to connect the manifolds. Dose your model allow for adjusting (and give references for?) smooth (PVC) vs corrugated tubing ?
BIG question: I had assumed 2 independent systems, 1 for each level to decrease manifold size/cost and to be able to utilize smaller / cheaper fans. NEW, if 3 levels, 3 independent systems and use one to zone on section with subdividing wall as more a warmer section??? (I see the lower cost in-line fan's at 400 and 720 CFM) Does your model account for design of 2 or 3 independent ground heat systems ?
Thanks for your consideration,
Robert
What happened?
@@jupiteradventure5284 Robb never got back to me, I sent e-mail to both his e-mail addresses and then posted this here per his wife's suggestion as the fastest way to get a reply.
so the pipes are empty and only the air from the greenhouse flows in them? no chemicals in them like in geothermal heat pump? do the tubes need to be made out of plastic or can they be made of metal?
You can in theory make them of metal. But that's going to be more expensive and more difficult to work with, for probably not a lot of benefit. Soil, stone, and air all have far lower heat conductivity compared to metal. The metal pipe would be like a Bugatti stuck in a traffic jam with all the GM vehicles. Fast in isolation, but limited by it's neighbors.
@@mattmanning1572 thank you for the info!! would this type of heating work with sunken greenhouse or is the idea of sunken greenhouse so that you don't need additional heating or cooling?
@@wiezyczkowata I should give a disclaimer first - I don't actually have any kind of greenhouse yet, so I don't speak from experience. I'm among the ranks of those 'planning to make one'. But as I understand it, whether or not a sunken greenhouse will work on it's own will depend entirely on your location, climate, and just how 'sunken' it is.
In addition, the temperature you want to maintain will influence the equation - do you want to just maintain above freezing to overwinter figs and citrus? Or do you want to have tropicals year-round, which would require maintaining perhaps 50F? Or do you want to actively grow tomatoes all year, which would require 65F minimum?
But in general yes this system of heat exchange with the ground should be a fine addition if just being sunken isn't enough. The less heating you need to do, the easier it will be for the ground source tubes to make up the difference.
@@mattmanning1572 thank you for the answer, it was very helpful!!
There is 100 things wrong with what you said. If you want to know how to do this properly contact me.
NO THANX,,,NOT AT 250. BUCKS,,,, why do you think we watch screwtube ???
sorry but this is a bull of crap, you dont need any of that stuff to design your system. Just use little common sense and experimentation.
A hvac enginner doesnt rely on common sense and experimentation to design a system. Its not as complicated as it seems.
Would it be feasible to use this type of passive system to heat water instead of air? I am interested if this can be used to regulate water temperature for a aquaponics system, in conjunction with an air system. I know that the ambient greenhouse temperature will mostly regulate the water temperature. Will this give better direct control of the water temperature?