Sounds interesting. Do you have any link so we can see that work?
I found his stuff through citrus in the snow. It was a weird thing that cost like $50 or something but now I can’t even get the login button to work. I’m not sure I’d recommend people buy it.
The chinese greenhouse is more of a kit. We can use it’s principles, but I would think it’d actually be cheaper to just buy the stuff from alibaba and use the kit. I haven’t priced that all out though because of the foot print of it. Those greenhouses seem more for professional people anyway since the blanket isn’t automated. If I had a few acres then I’d for sure price one out and would probably get one
As another thought point there are also folks adding rocket mass heaters to greenhouses to turn twigs and small branch detritus on their properties into efficient heat that gets stored in thermal mass and released overnight into the greenhouse.
There’s a guy in the Canadian prairies who built a greenhouse with basically what you’re describing - dug down a few feet, put down R40 insulation, filled back with sand(native soil would work) and inside the insulated envelope has pipes running down into the sand, and back up along the north wall to the roofline.
It’s a much more effective (especially in climates with colder deep soil temps) passive version of the “earth battery” concept.
I found a nifty way to heat my greenhouse a few extra degrees this winter!
This solar panel:
https://www.amazon.com/gp/product/B07WX6L3V6/
Hooked up to this power station:
https://www.amazon.com/gp/product/B09Y17YZL4/
With this thermostatically controlled outlet plugged into it:
https://www.amazon.com/gp/product/B09NLSZSX2/
With this clamp lamp plugged into it:
https://www.amazon.com/gp/product/B0002DHOE0/
With one of these ceramic heat emitters screwed into it:
https://www.amazon.com/gp/product/B0CGD67R6M/
And I kept the ceramic heat emitter right next to my tropical plants, which were sitting on top of my rain tank, and therefore had a bunch of water right underneath them to keep them a little warmer.
Voila! Whenever the temperature hit freezing, the outlet would automatically turn on and start pumping an extra 5-10 degrees of warmth right where my tropicals were. It’d last for only about four hours before running out of power, but that was enough to keep them just barely above 32 in the greenhouse when it was 10 degrees outside.
I’m thinking, next year, I’ll have two power stations and two heat emitters, so it can work to keep the greenhouse above freezing if the temperature dips down to 5 degrees (which is the coldest it usually ever gets here), or possibly even colder.
Now, I also had about 400 gallons of water in the greenhouse serving as thermal mass, plus another 750 gallons of water sitting against the north side of the greenhouse, and those kept it consistently about 15 degrees above whatever temperature it was outside, no matter what.
On top of that, I had added a second layer of greenhouse plastic to the whole inside of the greenhouse. I also, later on, clued in to the fact that if I put open buckets of water inside, as well as closed rain tanks, it made a huge difference at night, because the sun made the air humid inside. It was surprising what a difference that alone made!
But even then, I needed something, because I wanted to keep the greenhouse above 32 to keep my tropical plants alive (and, okay, also the tomatoes that I started in pots in February 
). Without any way to add new heat during the coldest time of the night, it was briefly dipping down to 25 degrees inside on nights when it was 10 degrees outside, and, well, I lost a few plants.
This setup made that difference. It made a 7 degree difference! I didn’t need it set up if the temperature was predicted to stay above 20 (which was most nights), but if I saw it was going to dip down to 19 or lower, I’d hook it up and sometimes find the battery depleted. All my tropicals and tomatoes that I started in there after putting in the heat emitter setup survived. Hurray! 
So basically, the heat emitter setup wouldn’t have been sufficient on its own – it may have, if I’d had four or more running concurrently – but in combination with a lot of thermal mass (all rainwater or greywater) and an extra layer of greenhouse plastic, I think I can consistently keep zone 10 plants alive in zone 7b, with just one little dinky 60 watt heat emitter and a thermostatically controlled outlet hooked up to a power station.
Awesome!
This setup certainly wasn’t cheap, if you count the cost of the solar panel and the power stations. But I had those anyway because I want them for emergencies. If you count only the cost of the thermostatically controlled outlet, the clamp lamp, and the ceramic heat emitter, the setup was cheap. And it made a full 7 degree difference.
So! There’s a thought if you’re hoping to have power stations for emergencies anyway!
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