Author Topic: For the love of concrete!!  (Read 722 times)

Pneuma

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For the love of concrete!!
« on: November 08, 2023, 10:14:45 AM »
Jabo house top of my driveway which is pretty large and full sun besides where GH is kind of tucked under some oaks a little.



So I put GH here for a bounce of reasons but 1 benefit I didnít expect is the heat retention of concrete check this chart out itís insane to me.  I even used a different sensor to double check data it confirmed.



44degs was the low last night my low temp was 65degs with no heat just a small circulating fan.  My other GH not on concrete needs heater and it ainít cheap to keep it over 55degs.  Will be interesting to see in the middle of winter if GH will hold warmer temps throughout the evening with no heater 🤞🏼

Added other GH data just to compare that has a heater and struggles to hold my 55deg desired low temp

« Last Edit: November 08, 2023, 11:58:26 AM by Pneuma »
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nattyfroootz

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Re: For the love of concrete!!
« Reply #1 on: November 08, 2023, 10:28:58 AM »
What sensor ya got there Wes?

Looks awesome! Gotta come check it out one of these days
Grow cooler fruits

www.wildlandsplants.com

Pneuma

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Re: For the love of concrete!!
« Reply #2 on: November 08, 2023, 11:53:46 AM »
https://www.amazon.com/gp/product/B0BMG2XVDN/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&th=1

Nate only downside is u need wifi to log data but u can access anytime live on phone with App or online where its saved which is most important to me so I can back and observe.  There are better brands but for $60 its been good for me.   The cannabis nursery we use Pulse Pro sensors but they're $500 each and a little over kill for jabo house hahaha but is a great tool nonetheless.  Cheers
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K-Rimes

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Re: For the love of concrete!!
« Reply #3 on: November 08, 2023, 01:10:04 PM »
I also have my GH on concrete (asphalt anyways) and think it's a winner for the winter. If we get consistent sun during the day, it holds temps nicely. Last winter was rough, it was flooding all the time and barely any sun to heat it up.

Tropicaltoba

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Re: For the love of concrete!!
« Reply #4 on: November 08, 2023, 04:45:23 PM »
Another neat idea is to use phase change materials (pcmís). Water barrels work like this, if the water were to freeze they release a huge amount of energy (100x what you can get from a concrete floor) they also use special salt solutions and waxes. You can really nerd out on this stuff, but you start to sound kinda weirdÖ and eventually people donít want to talk to you anymore, so then you just talk to your plants. Iíll shut up now.

NateTheGreat

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Re: For the love of concrete!!
« Reply #5 on: November 08, 2023, 05:21:02 PM »
Another neat idea is to use phase change materials (pcmís). Water barrels work like this, if the water were to freeze they release a huge amount of energy (100x what you can get from a concrete floor) they also use special salt solutions and waxes. You can really nerd out on this stuff, but you start to sound kinda weirdÖ and eventually people donít want to talk to you anymore, so then you just talk to your plants. Iíll shut up now.
Good in theory, but if it's really 100x better, where are the real-world examples? Pneuma has experimental data showing his concrete works much better than I'd have expected, basically not needing a heater. You're saying PCMs could keep his greenhouse above 60 degrees 100x better, so what, for 1/100th the cost? Let's say it's 10 grand of concrete. What can you do with $100 worth of PCMs? Could you even do it for the same cost?

fruitnut1944

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Re: For the love of concrete!!
« Reply #6 on: November 08, 2023, 06:13:06 PM »
The concrete will only work well following sunny days. And right now, the ground is still warm from summer. The cloudy season is about to begin in CA. And by mid winter the ground heat will be drawn down. On cloudy days in spring the concrete isn't going to be supplying heat and could even be a negative. Who wants to heat up concrete? not me.

I'd have that shade cloth off there soon. That reduces heat gain by day. But then the structure apparently lacks another cooling option. So over heating could be an issue on sunny days especially next spring.

Tropicaltoba

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Re: For the love of concrete!!
« Reply #7 on: November 08, 2023, 06:48:55 PM »
Nate, I just thinks itís a cool concept, but you are right not suitable as building material as of yet. We need more people doing research in advanced materials for greenhouse design so that everyone can grow tropical fruit.

K-Rimes

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Re: For the love of concrete!!
« Reply #8 on: November 08, 2023, 06:55:22 PM »
What we really need is insulation UNDER the thermal mass, then you'd be cooking with gas.

I can't fit any barrels of water, greenhouse is full. If I water my plants enough, isn't each of them a barrel of water anyway?  ;)

My GH is good for around 5f in cloudy cold weather, and 8-10f on a nice sunny day, with no insulation of the structure at all. It's something.

BTW I am using SensorPush sensors. The new sealed ones hold up much better than v1.

Jaboticaba45

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Re: For the love of concrete!!
« Reply #9 on: November 08, 2023, 07:00:50 PM »
The idea of using water to help heat the gh is a nobel idea, but in practice it doesn't make a difference unless you have a hecka ton of it. Then at that point, you're running out of space.
I got 6 barrels, but in the end, they just took up extra space.

Pneuma

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Re: For the love of concrete!!
« Reply #10 on: November 08, 2023, 11:20:42 PM »
I'll post again in mid Dec.
I think 55deg low night temp with no heater is doable cause we get alot of sun all year (My place runs on solar all year)
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Jeramyl

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Re: For the love of concrete!!
« Reply #11 on: November 09, 2023, 01:48:26 AM »
Or just go wild and do what Iím going to doÖ build the greenhouse over a hot tub!

My hot tub is well insulated but still some heat loss which =heat gain for greenhouse!  Plus added bonus of seeing the plants while you soak!

Win-winÖ

NateTheGreat

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Re: For the love of concrete!!
« Reply #12 on: November 09, 2023, 12:03:00 PM »
Please post your results Jeramyl.

It'd be cool to see a greenhouse built around a boulder. Or over a concrete cistern.

Kevin, I don't know how much insulation would do, since the subsurface ground is probably around 65. Especially as you get away from the edges into the center of the greenhouse. If anything, it might hurt once the greenhouse dips below 65. It'd be neat to have metal heat exchanging fins down into the ground below the slab. Maybe geotubes are just better? Or metal geotubes.

spaugh

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Re: For the love of concrete!!
« Reply #13 on: November 09, 2023, 12:32:32 PM »
Have you guys seen the rocket mass heaters? 
Brad Spaugh

K-Rimes

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Re: For the love of concrete!!
« Reply #14 on: November 09, 2023, 12:54:39 PM »
Or just go wild and do what Iím going to doÖ build the greenhouse over a hot tub!

My hot tub is well insulated but still some heat loss which =heat gain for greenhouse!  Plus added bonus of seeing the plants while you soak!

Win-winÖ

GOALS!!!

Quote
Maybe geotubes are just better?

I would think so, if you get deep enough. Mostly for cooling and keeping it really average temps in summer would be of most interest to me.




 

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