Deep Winter Greenhouse: Heat Storage Systems & Their Trade-off's

[@bcarroll03]

A follow up on the last 2 years of performance would be amazing. Thank you so much for this incredible resource!

[@janbruns3670]

A question about the “sealed rock bed” I’m planning a grennhouse build next fall. And I’m reading & watching everything about this geo-thermal stuff for the last couple of weeks coz it’s really new to me, so excuse me if my question sounds funny or naive…🙂 well anyway. The rock bed thought makes sense to me coz there u storing the energy not in the air in empty pipes. But if the even distribution of air through the rock bed is very difficult, why not laying a number of pipes to connect intake and exhaust. But not the small ones for only air, but pipes in the same sizes of the intake and the exhaust and filling those with rocks, isn’t that a easy method to direct the airflow through the rock bed??

[@kitchencone]

I'm late to the party but have 2 observations: You could better balance the manifolds by using a loop manifold at each end. Each loop would have a horizontal leg below ground, (same as now), a vertical leg at each side, leading to another long horizontal above ground. Intake and exhaust are short verticals that tap into the middle of the upper horizontals. The air may bias the sides with this approach (instead of the middle) but that will spread the battery heat better. Even if the middle is slow, it's temperature will be pulled along by the two neighbouring sides. To get better heat transfer, punch many 2 foot lengths of steel rebar through the plastic transfer tubes and into the soil. The air will hit the center of the rebar pins inside the pipes, and the steel will conduct heat better along the bars and a foot into the soil toward each end of the bars. This should increase the "speed" of the battery.

[@napalmholocaust9093]

Super later to the party. I'd have a cold well if you don't want to use secondary heat when the banana was lost at 29°. Maybe a temporary "blanket" for the glazing instead of or in addition to. That is a problem of curves. I've seen hinged panels of foam on plywood but it was for flat constructed walls always. Interior roll-down blankets I have seen from a 70's book. It had curved rails that matched the half-hoop and the insulation stayed against the curve. Think roll-top desk but fabric and not a desk 😃

[@stuartwakefield1657]

I live in the UK and we are told to put the tubes down at 8ft = 2.4m. It seems the ground is more stable at that depth.

[@waywardspringsacres]

That is correct if you are using low grade geothermal which is earths natural accumulated heat. However in this video we are covering systems where excess heat is stored in the ground boosting it much higher at a shallow depth.

[@thedomestead3546]

Thanks for providing great content for the public. ✌

[@specialkaypb]

paid for.... by the public lol

[@thedomestead3546]

@@specialkaypb like subsidiary crops

[@chriskay7233]

​@@thedomestead3546that's my point.

[@TerrenceArbic]

I would suggest internal baffles in the gravel bed to minimize 'short circuiting' the heat flow directly from inlet to outlet. Perhaps patio blocks set vertically in a checker board pattern. would force hot air around the baffles and cause some turbulence.

[@sunworksco]

The sand battery system can maintain a 75F temperature all winter long, near the Canadian/US border.

[@manofsan]

Is there one over there? Where precisely is it?

[@CarolReidCA]

Excellent discussion! Thanks! I've seen glass water columns with a black bottom and reflectors on them that can boil water (thus the glass & not plastics) on a small scale. If you have a clear roof and a sealed greenhouse, it would be much like parking a car on a sunny day. A car can get dangerously hot, however, so ventilation would be needed for warmer days... a thermostat and ventilation/cooling system would be needed, as was mentioned. A double-walled system would be helpful as well. I like the LGG passive systems using tubes with air for underground to greenhouse air exchange. No batteries required, except perhaps for ventilation and a thermostat, which could be done with some small solar panels. You could have manually controlled vents on the top to cool, as needed, unless use of fans is needed, particularly in a larger green house. Using Boyle's, Charles laws could get some math into the equation that would help in building more efficiently as well. I'm curious about the costs of building these manifolds??? There needs to be some heat loss at night for plants to cool at night, which is why hoop houses have been used so long, yet we still don't want them getting too cold or hot either way. Use of hot compost to warm, as is breaks down, is also an interesting heat source. I just found your channel today & subbed. I hope to hear more from you in the future! To the man with research grant #FNC19-1185, I Can't tell if that flower by you was a small echinacea or a large sunflower... the picture is too small to tell. I'm curious where you can buy those curved trusses, or do you have to fabricate them? It would be helpful if you could blow up your diagrams, so they can be seen better and read on say a 32" TV. I can read the 0, 2 & 4" polystyrene insulation on the screen, but the compared heat loss from none to "chosen design" on the smaller diagrams aren't readable, on my end. Most of the PP, or similar presentation are fine. I agree that the air movement being consistent through the manifold, with temperature variation, tighter degrees through the manifold, could be challenging. I would think a wider radius curve to make the 90° turns, would help. Very interesting & useful stuff! Have you used insulated tubing above ground, ie above the underground manifolds? Great stigf!

[@Boobear83]

Quick question: if you had a 100ft long passive solar or winter greenhouse, would it help conserve heat or loose heat or not even matter if you put partitions into it? I just had the thought in my head of creating barriers to cold spread like the chambers on the titanic to keep it afloat…….but wondering if the bigger area would hold heat better or if many smaller areas would be better. Thank you for any responses anyone may have.

[@guywilliams3108]

How do you control the air flow through your manifold through your Earth battery to keep the air going through your manifold evenly

[@AKDanMusicMan]

Around 1:27:00 you mention you might do away with the clerestory if you had to do it over. I was wondering if it might actually benefit by making it a bit taller and painting the exterior black to increase the heat at the top of that space that then gets pulled into the climate battery below? It would also isolate the hottest air for pulling into the tubes and there would be less mixing of air as it circulates below?

[@guywilliams3108]

Will the earth battery affect a CO2 system if I have it in my greenhouse

[@TheDomi44]

with a geothermal Greenhouse is there any benefit in insulating horizonally above the heating tubes?

[@AKDanMusicMan]

Would there be any gain (or loss) by adding another layer of tubes at 6' depth? You mentioned around 1:21:00 that you weren't able to store the excess heat at the peak of summer. Wondering if adding layers would allow for more heat storage in the climate battery, or would you get diminished results because the ground is cooler and possibly working against you the lower you go?

[@martinwinther6013]

you would need unimaginable amounts of insulation if you want to have any hope of storing summerheat all through to the winter(assuming 4 seasons is a premise)

[@AKDanMusicMan]

@@martinwinther6013 I wasn't saying store it until winter. He said that they couldn't store all the heat from that day and had to vent it out the roof. If they had more tubes, maybe they could store it and have a more prolonged release than not having them.

[@allanm9913]

I'm thankful for the people who make these videos for the public. Heat storage is a topic that is important to our lives. Does the University of Minnesota have a media department? The scripting could use some work.

[@441rider]

I am researching urban use in small geothermal solar growing of coffee citrus cherries and other fruits. I am installing a compost heater furnace to my circulated earth battery duct. All is powered by solar in Vancouver BC 8b zone. 18" frost level. I also put layers of foil emergency blankets over my battery area then 2 inch foam. Blue light stunts growth far red increases growth as it penetrates leave better. I use aluminum 3 inch duct x 30ft perfed only near battery soil.

[@karstenschmitz1]

This video is extremely helpful. I have one question, though. The slide that shows “Heat Storage Capacity of Common Materials” at 20 mins 8 secs has a sample calculation for estimating the heat storage capacity of a climate battery. I’d like to use this slide to estimate how large my future greenhouse should be to heat my future home, but there is an unknown factor which prevents me from using this formula. How could I predict how much the soil will heat up (temperature differential)? Even though weather data would indicate climate trends, I don’t know how much the climate battery would heat up from sunshine hitting the surface area of the soil. Any suggestions on how to predict this?

[@waywardspringsacres]

That is very complex and depends on many factors such as: your climate, day length, sun angles, glazing material and angles, size of structure, effectiveness of fans and tubes to move heat into the soil, soil thermal conductivity, soil specific heat, etc...so unfortunately cannot be summed up very simply. I can see at least 5F rise on a sunny day, with a better design it could be more.

[@pault.juckniess7265]

One of the factors that seems to be missing is how moist is the soil. Someone mentioned that the soil was drying out faster. We should expect that the more moisture that is in the soil , the greater heat capacity and better heat transfer.

[@Brians-Easy-Low-Tech-Solutions]

What is the reason for "not" using say 4 ft deep of water storage under the greenhouse and a car radiator for heat exchange? You could have a sheet of plastic suspended at 4 or 6 inches high off the bottom to have " thermal stratification" (heat travels up by convection easier than down by radiation in water) so maybe you would have more effective "insulation" by using water as your storage and then either directly connect the rest of the water to the radiator or have coils of pex pipes going through your water storage near the bottom for an indirect system. I suppose I am missing something pretty big but wouldn't it be cheaper and simpler?

[@t.b.a.r.r.o.]

I should be building spring or summer 2022. My soil is very spongy with a water table less than 3 feet below the surface. I want to put PEC tubing at or below the water table. I'm assuming the response time will track somewhere between that of water and soil. I'll be using a draindown system with 2 - 4x8 homemade solar panels beside the GH. Solar heat to storage during the day when the GH doesn't need help. Circulation changed to heat when needed. Because I'll be doing aquaponics I'll use battery heat to control my grow bed/fish water temp by placing a coil in the reservoir. That will be set to a high/low - summer/winter range thermostat. Also the growbeds will have there own heat coils if needed. (I'll be doing a decoupled aquaponics system so water that goes to the plants will never return to the fish.) I am curious to see how the high water table will work as a battery.

[@nickrowe9221]

high water table will wash away your heat you can't store in it. you must store someplace else. you can however use the ground temperature of the ground water 56 degrees or so as a heat source.

[@t.b.a.r.r.o.]

@@nickrowe9221 Thanks for the input. I'm not expecting long term storage. More like collecting during sunny days using a couple 4x8 panels, then drawing that over the nights and cloudy days as a way of reducing reliance on other heat sources. Just trying to reduce fuel and electricity costs during winter. In the summer I'm hoping the heat dissipation into the water table will help keep the fish tanks at lower temperatures too. I'll be documenting everything. If it works out as useful and a cost savings I'll post that. If not, I'll put that up too. Btw... Long COVID cost me a full year. Plus a heart attack set me back a few more months. I'm running about 18 months behind schedule. Working hard to catch up. 🎱

[@nickrowe9221]

@@t.b.a.r.r.o. I had it too almost died the first night but they put me on whatever they gave the pres and first lady, and I was only out of it for 2 weeks... weird. I have a lot of connections to the solar/wind energy area. They have just come out with a heat pump that is 10 times more efficient Its a game changer. So you could go that route as well. I was planning on doing solar with 7000 gallons water storage to give me a summer through winter system for my home but am only doing a redundant hot water now (700 gallons) and will use the newest heat pump with PV. Best of luck, Nick

[@t.b.a.r.r.o.]

@@nickrowe9221 Wow... Glad you and I survived! The heart attack almost got me. I'm fine now but it was do or die for about an hour.

[@babbarsher2065]

@@t.b.a.r.r.o.. Chia seeds soaked in water. Overnight. Put. Extra virgin olive oil. And Cayenne Peeper. Drink in mornings. Good for heart and stroke cleans arteries Motivational Doc. On u tube. 💘🌎🕊. 👍🏿. 👁🌎👽🛸

[@sherrylesser]

I live in Central Canada; zone 2/3, and have a small backyard greenhouse and two properties with large gardens. I wish to build a passive solar greenhouse or improve the existing greenhouse for my climate. I am wondering if: 1. Is it feasible? 2. What system would be best? 3. Is there any way to make one that has zero additional energy inputs? 4. Is there any way to build something with only solar energy inputs? 5. Is there any way to make an off grid system for use on a farm away from all utilities?

[@gregschweser]

1. A passive solar greenhouse is feasible in your area. 2. What would work best would depend on your goals and your budget. If you want to be as energy efficient as possible, and you only need a smaller greenhouse, you might look to our DWG 2.2. designs. If you want to build a larger scale greenhouse for more commercial production capacity the farm scale greenhouse is probably a better fit. You could combine the two and make a larger greenhouse with an insulated underground rockbed if you have a large enough budget. There are also many other options like those developed by CERES in Colorado, or many of the designs found on youtube or google if you search for 'solar thermal greenhouse' or 'Chinese greenhouse.' The examples will range from too big and too costly, to too small and not suitable to cold climates as well as everything in between (which is where you fill find your sweet spot). 3. I don't think it is feasible to make one that requires zero energy inputs. There will always be cloudy days when the heat battery can't charge and if you go below 0 (32) your plants will die. Even the best models will require some small amount of regular backup heat. 4. If you use only solar inputs, you will need to have a battery or powerwall setup that can charge your electric backup heaters and your fans to move the air around between the thermal mass and growing area. Those fans are needed at night when the sun doesn't shine. 5. Like the answer to 4, if this were entirely off-grid, you'd still have to supply with reliable power to keep the fans running and backup heater going. So, if you could do that with electricity generated on site, and if that electricity is storable and reliable 24/7 you could do it, but you'd just want to be careful you don't run out of power in the middle of the cold nights.

[@TallontedTinkering]

How dus the system operate, heating vs storing? As in what fans are running which way and is it the upper or lower system?

[@gsanning]

What about using a radiant floor heating system. This combined with a solid concrete foundation would create a very good consistent heat to the greenhouse correct?

[@waywardspringsacres]

That would not be solar powered, unless you are thinking of water heating solar panels, which is definitely and option, but tends to be more costly is most situations.

[@JohnGuest45]

You have to use a combination of insulation and heat storage or you will be wasting your time. The tradeoff with tube spacing is very logical, that closer spacing reduces the amount of mass between the tubes so you have less capacity but a faster response. Wide spacing is the opposite. Most systems opt for a happy medium of 2ft horizontal and 1ft vertical tube spacing. Its important to note that heat stored in the mass during the day will remain within reach of the tubes that night. Typically heat that migrates further than 1ft from a tube cant be recovered the same night, which is the main reason for the standard 2x1 tube spacing. Its easy to see how the tube spacing can be used to bias a system to work in harmony with the local climate or even a specific location. For example, a greenhouse may be situated where it only receives a few hours of bright sun per day. The mass in a very close spaced layout would achieve a higher temperature (more tubes influencing less mass) where a wide spaced layout would be cooler due to less tubes heating more mass. Basically its a case of tube density, with the caveat that tubes displace mass, so the more tubes you place in a given space, the less mass you`ll have. Your daily performance example doesnt show relative humidity or airflow rate which are required to calculate the heat transfer. The latent component makes up the bulk of the energy transfer to the mass during cooling. The latent component makes up a large percentage of the total energy removed from the mass during heating, as you know the latent component doesnt increase the air temperature, it siimply increases the RH%. To get an idea of the system performance you need to know the average temperature of the mass, the real system airflow rate, the inlet temp and RH%, the outlet temp and RH%. If you have a temperature sensor installed below the system you may notice the average temperature of the ground rising, at least for the the first 5 seasons, which confirms heat is lost downwards which eventually slows due to the increase in temperature.Growing in the ground has the benefit that you need to water less as the condensate is returned to the roots. Plants are a critical part of the system, transpiration not only cools the plants themselves but also creates the humidity that provides the lions share of the heat transferred to the ground during cooling. In my experience with a system capable of a turnover rate of 60 airchanges per hour, its not easy to outrun the cooling capacity of a tube, even a short tube. With a temperature differential of 30 deg F btween the mass and the inlet air, you will need to run at least 25 airchanges per hour to raise the exhaust air above the mass temperature. Diminishing returns begin to kick in at around 45 airchanges per hour. For energy efficiency you should run the fan at a speed that keeps pace with the incoming gains to maintain the desired greenhouse temperature. Running the fan flat out interrmittantly is less efficient and less than ideal for the plants. Its great to see folks experimenting and doing real world testing, if you build another system give me a shout before you finalise the tubing layout. :)

[@waywardspringsacres]

Those are good clarifications and explanations. Unfortunately we had strict limits on the length of our webinar so I had to cut out many details about the extent of sensors, explanations of sensible vs. latent heat transfer, etc (and everyone might've fallen asleep :)). I'd like to put together some more detailed, non-time limited information on that at some point. Maybe I can get some more grant funds to further optimize the system and develop better training/guidelines. There is so much poor/misinformation out there that it is very confusing to growers and builders and northern climate agriculture could really benefit from these simple systems.

[@JohnGuest45]

@@waywardspringsacres I didnt have the luxury of a grant so i spent a long time at the drawing board exploring every possible option. I count myself very fortunate that i had John Cruickshank to bounce my radical ideas off before his passing in 2011. The final result was a completely different design to anything before or since. One of the main goals was the system should offer plenty of scope for experimentation. Back in 2009 there was very little real world data coming from the installations that were out there. Most of the installations on you tube use designs with the same flaws. John used to say, its plain to see as the nose on your face. You wont see it until someone points it out and then it suddenly becomes obvious. You are on the right track with the design but if you can think a little more outside the box you may have a eureka moment . Its plain to see as the nose on your face :)

[@brendanmchenry6532]

Would using water instead of air help to improve the efficiency?

[@Nya875]

@JohnGuest45 How can I communicate with you on questions for an open source project if you're willina?

[@snickerstoasted2212]

very detailed info thanks a bunch for putting in the effort

[@liambenyamin5482]

OMG!! Any shmo can know information! To inspire, light up and support thru teaching is a rare precious gift. Please allow teachers to teach. If you can't; Don't block a space from being its true something just because you want a salary and title. Please

[@dustygreene3335]

one thing i have heard about the design shown is having the top tube layer only 2 ft from the surface can have a tendancy to dry out the soil. But im very curious what his results will be long term.

[@waywardspringsacres]

My email is on the last slide of my portion of the presentation.

[@vincentjean6756]

Excellent presentation! Thank you!

[@UtahOSR]

What about a hybrid of the two types in this video? So, from the bottom up: Cover the lowest level of perforated pipes with rocks along with the space in between them, then a layer of plastic (or corrugated pipe fabric), then soil, then rocks surrounding the upper level of pipes, then more plastic, then dirt? That way, the air can flow out of the pipes more readily, but you don't have to pay for rocks to fill the entire pit. Best of both worlds?

[@zachs5231]

Are there any resources, materials, or other information available from U of M about how the DWG design would scale to 5000-10,000 sqft? Thank you for posting this webinar!

[@waywardspringsacres]

Sorta, Look at the Farmscale Deep Winter Greenhouse design drawings. That is in the 1400sqft range. Sizes over that are also feasible by increasing the length. Usually, they are a maximum of 30ft wide though. I plan to build a 1500sqft version soon.

[@cherrytreepermaculture756]

The Farm Scale one could be extended lengthwise indefinitely, if you have the space for that.

[@shawnburke6016]

I’ve been following deep winter greenhouses for a while. We finally poured our 5’ insulated foundation. We are 16x40 and in Clearwater Bc Canada we are zone 4 abd get 4-5’ of snow How many fans were you running? Do you like black flexible pipe better than solid white perforated pvc. Can you recommend fans and how much pipe I should put in the ground I was thinking 2 layers 24” oc. Great data! thanks for all your work

[@JohnGuest45]

A greenhouse that size would require around 850ft of tubing. The fans will depend on the volume of the greenhouse and the tubing layout.

[@mikerobertson6663]

I’m jealous! But I’m glad you’re getting going on your project. I want to get one going as well. I’m in zone 6 so it should be a piece of cake to keep a green house warm here. Wanting to grow more sensitive tropical plants as well . I’m not sure how air flow works when it comes to different size pipes . I start by figuring the actual area of the pipe . We can easily get fooled when it comes to this . For instance a 36” dia. Pipe has 1018 sq inches of area. A 6” pipe has just over 28 square inches of area, that would take 36 of these pipes to equal one 36” pipe . That just doesn’t seem possible.

[@tonysu8860]

Interesting. in the past I've mostly considered higher temperature storage mediums but simply using air and soil is an interesting concept. It's certainly lower cost and involves less stress, and likely would involve less loss and engineering requirements. For greenhouse applications,, the perforated tubes for draining excess moisture and the observation that air circulates into the soil and dries it out is interesting because it highly resembles is doing what a lot of "no turn" composting piles are attempting to do... I bet you could turn what you consider a problem into a highly desirable feature by converting that part of your "soil battery" into a no-turn compost pile where the tubes inject fresh air/oxygen and microbes into the interior of the compost pile. Although I still wouldn't consider the result anywhere close to properly done hot compost, this is adequate for a lot of people. You'd also be creating a biological heat source up to about 120 degrees F which I believe is the most common use for greenhouses which is to provide an environment warmer than the ambient air rather than to provide a cooler environment than the ambient air. Of course if the objective really is to cool the environment, then you could simply not do any composting and draw from the natural cool temperatures of the earth.

[@belspace]

Great stuff. Many thanks for sharing.

[@RichardHauser]

Three questions: 1. Are you loosing heat from the mass down to the ground i.e. are you winning or loosing due to deep average heat temp. 2. If water is 4x the density, why not use a quarter the volume and then just do water to air radiators or pond line the rock bed and pump water thru 1/2 the volume? Radiators are cheap and efficient. 3. Any worries about mold in tubes?

[@umnextrsdp]

A great resource to ask your DWG questions is the Deep Winter Producers Association Facebook group--a very interactive community of those interested in deep winter production: facebook.com/groups/845092875544652

[@JohnGuest45]

You will lose heat to the ground below the system initially but in my experience it does stabilise to a new "normal" based on the new energy balance. I guess you can think of it as a one time investment of heat that you will never get back that provides benefits to the system for as long as it is in operation. It took 5 seasons to stabilise in my case but ymmv as it will depend heavily on the design and operation of the system and the local climate. Water has a 4x the heat capacity of soil but it doesnt provide the same advantages. If you put the heat gained from a couple of hours of winter sun in a large mass of water it will make almost no difference to the temperature. If you run the heat through tubes in the ground the heat will remain in a relatively concentrated form close to the tubes where it can be recovered for use later that night. My tubes have been in the ground since 2009 and i`ve never had any issue with mold etc. I sent filter samples to a lab to be tested for peace of mind and there was nothing of concern in the samples, just the normal flora and fauna you`d expect in a healthy greenhouse environment.

[@RichardHauser]

@@JohnGuest45 1. Yes, that makes sense, you are kind of changing the average ground temperature under your greenhouse. 2. "If you put the heat gained from a couple of hours of winter sun in a large mass of water it will make almost no difference to the temperature." Yes, that is what heat capacity means, being able to dump huge amounts of heat into a mass and have almost no temp change because once the temps match, the battery is full. What it sounds like is that you need to use a water mass and dump even more of the heat into it. In my view, and correct me if I am wrong, if you are venting heat in a season where you need heat at night, then your mass or the system to interface with the mass is failing. Every one of these videos mention how important venting is EVEN IN WINTER, and then complains that there is only so much heat you can get back out at night so supplementary heat is sometimes necessary. Doesn't that tell you that the battery isn't doing enough? I think if you did half your digging and just did a 4'x4' trench and filled it with insulated IBCs at 330g and heat them 20 deg.F then you store 55kBtu of heat or the heat of 2lb of propane EACH! If you have a 24' greenhouse and you just do one line then you get six of them. And they do TWO tasks, they make your nights AND days better. All you have to do is add the piping, six car radiators and pumps and the vents will now be for emergencies or to store cold in the summer nights. Am I missing something? Here is someone who did it with a fraction of the amount of water I am talking about: northernhomestead.com/car-radiator-for-heating-and-cooling-a-greenhouse/?fbclid=IwAR1jhEXcQolVdFrRB5Wlih94jZ_hPXgAPXIh3lVf_ljdQ92fE-ghBFkoqME

[@JohnGuest45]

@@RichardHauser There are two main reasons for venting heat that could otherwise be stored., one is not having enough capacity to store all of the available heat which is true of most installations when you consider how much energy is delivered by the sun. By far the most common reason is that the system isnt able to move and store the heat fast enough to keep pace with the incoming gains. Consequently, the greenhouse overheats and you are forced to vent. In this situation, it doesnt matter how much mass you have, :) The difference between a thermal mass of water and soil is that when the water drops below a useful temperature you will need a massive amount of heat to bring it back up. Most places dont get a lot of sun in the winter which makes this a lot more difficult.. With soil you dont have to worry about adding massive amounts of heat,, you can get by on a hand to mouth basis because the limited heat isnt dispersed into a large mass. If you are going to use water as mass and car radiators for heat exchange you will need to move considerably more air than with buried tubes. If you consider a 2ft x 2ft car radiator with 1000cfm of airflow, the air will take about 30 milliseconds to pass through the radiator so the opportunity for heat transfer is very limited. The radiator itself will absorb heat directly from the greenhouse and could be subject to direct sun which will reduce its ability to cool the greenhouse air.

[@RichardHauser]

@@JohnGuest45 Absolutely, the key design features of a thermal battery system is first a system to get the heat into a battery as quick as it is generated and then having a large enough battery to store it all. I think the flaw of soil systems isn't the size of the battery, but the speed the battery can be charged. That is also why water is better. Water can use conduction AND convection to transfer heat, unlike soil which can only use conduction and cause the soil around the pipes to be heated in a gradient, instead of being heated evenly which is why you have to use so many pipes. You may be right about the car radiators though, they are designed for a very different situation, so you would definitely want to slow the airflow through them down to a level that would maximize heat transfer at such low thermal differentials. I also agree you want to keep it out of direct sunlight, but again for the money that soil designs put into all that piping and gravel, you could buy MANY radiators and fans and line them up at the peak of the roof under the overhang. Then if you found out that the system was under performing, you could just add more and more till you maxed out the storage and then add more storage if necessary.

[@MsZzzipper]

Thank you so much for this!!

[@dustygreene3335]

I would love to hear more and somehow get in touch with you guys.....I am a fellow minnesotan and i have been passionatly obsessed with deep winter greenhouses for years and I just stumbled accross this now. where can i reach out to ?

[@6478nick]

Does this hold economical sense. Investing on system,, running and operating cost. Lots of labour on day to day basis.

[@waywardspringsacres]

That is really the most important question! Operating cost is very low as is labor, but the initial build cost is much higher. It ultimately depends on the value of what you are growing and how efficiently the area can be used. I feel there is a lot of easy room for improvement though.

[@erich4329]

Do you have a sharable PDF file of the slide info from this presentation?

[@nocogarden]

It’s a shame it appears no data was collected on RH which tells the other half of the story about the indoor climate.

[@LordGunigugu]

Great video! Thanks guys. But I'm always wondering why the manifold diameters are so small? I would really appreciate it, if someone could explain that to me. In my mind... for perfect flow the manifold circular area would best be the exact sum of the ground pipes circular areas. Am I wrong?

[@RichardHauser]

To get the same thermal battery as 4x16x24 of dirt you'd need just to bury 12 IBCs or skip the backhoe and put 12 IBCs in the back wall for a fraction of the price then just get 24 car radiators & fans plus a small water pump.

[@umnextrsdp]

A great resource to ask your DWG questions is the Deep Winter Producers Association Facebook group--a very interactive community of those interested in deep winter production: facebook.com/groups/845092875544652

[@waywardspringsacres]

@@RichardHauser Water based heat storage using the 275gallon IBC tanks is definitely an option. It would be great for someone to put together the cost comparisons and space trade-offs for that. It is particularly interesting for situations when excavation is impossible or costly due to bedrock or high water table.

[@guywilliams3108]

Can you give me the average cool temperature in the average warm temperature

[@dustygreene3335]

I know this is about greenhouses.....but it sure would be nice if our houses were also designed to at minimum not get below freezing to at least passively keep our pipes from freezing.

[@nickrowe9221]

it is being done. look at net zero homes. also there is a development for many years in Alberta Canada look into that. They collect all summer and store underground and in a shed behind each house using water.

[@dustygreene3335]

@@nickrowe9221 yes....I can't remember the name of that project in canada.....very cool

[@guywilliams3108]

Maybe with water and then bury them along with the piping add 2 l bottles in between your solar battery piping

[@brendanmchenry6532]

Really interesting- thanks for sharing

[@gilbertarzner]

Shouldn't our university's have been working on this to start with, instead of people like Russ the mailman figuring it out?

[@gilbertarzner]

Now they are trying to tell us how to do it. Everything that I learned from Oregon State University Crop Science program is now BS. Just ask Gabe Brown.

[@Boobear83]

Amen…..

[@georgemckenzie2525]

Condensation is the mechanism of heat transfer Sock pipe rewuired!

[@AutoEngineerVideos]

No, glycol doesn't increase the heat capacity. It reduces the heat capacity. The purpose of glycol is as an anti-freeze, and for automotive applications (not really relevant for greenhouses unless you have a wood heater or similar), it also increases the boiling point of the water. In fact, in the mixtures used in the automotive world, the proportion of glycol is very much sub-optimal as far as heat capacity is concerned because the proportion is chosen specifically to prevent the coolant mixture from expanding if it gets cold enough to freeze (ie: the contraction of freezing glycol is enough to counteract the expansion of freezing water). This is to prevent extremely low temperatures from bursting the coolant system. So... now you know... unless you need the anti-freeze/anti-boil characteristics of glycol, you might not need it in your water-based heat storage for greenhouses.

[@mehboobahmed3076]

Hello sir who r u am mehboob from pakistan ur vidio r grateful sir I have 5thousands feet land but have no investment sir I want to prepared nursery far tunnel farming and want to export hwo can u help me in this matter

[@guywilliams3108]

Farm scale but I'm in Tennessee

[@brennagarten317]

don't true heat pumps use the difference between input air and output to create heat?

[@waywardspringsacres]

In this webinar we talked about air-to-ground heat exchangers, which are not to be confused with "heat pumps".

[@garynickel648]

It is rude to interrupt him. Say questions to the END

[@bcarroll03]

Passion fruit flower

[@guywilliams3108]

Backup heating like a compost pile

[@eddieseward1649]

Excellent video…..except for the constant lip smacking. As Jerry Seinfeld says “Oh the dreaded lip smacker, for the love of God does he have to keep doing that?

[@hawaii8461]

Dude please try to cut out the uuummhhh uuuhhhmmm on the next video

[@tzenophile]

UMN is the name of the University- duh

[@butymetree7340]

arabic

[@billgreenjr1]

Bigger rocks lets air flow and hold up concrete

[@ChrisBeckPortableLogMill]

Just a thought... I think you could get 5 to 7% more solar heat gain if Shannon was to trim his eye brows. Lol

[@railroaded1299]

ffs.

[@wendydevereux4375]

How have you been paid for years to churn out existing knowledge as though it is yours. I was always told you need to understand a subject before you can teach it.. your waffle clearly shows you do not understand your subject

[@davidh9368]

seems they are being paid to learn, not teach. but if we all learn something they share then ok.

[@shawnburke6016]

I’ve been following deep winter greenhouses for a while. We finally poured our 5’ insulated foundation. We are 16x40 and in Clearwater Bc Canada we are zone 4 abd get 4-5’ of snow How many fans were you running? Do you like black flexible pipe better than solid white perforated pvc. Can you recommend fans and how much pipe I should put in the ground I was thinking 2 layers 24” oc. Great data! thanks for all your work

[@umnextrsdp]

A great resource to ask your DWG questions is the Deep Winter Producers Association Facebook group--a very interactive community of those interested in deep winter production: facebook.com/groups/845092875544652