Passive WINTER greenhouse works!!! here is the proof :-)

So many online forums have inspired me to build this, permies included, and now just want to share how it is working! 4 season greenhouse in southern CO, where we were able to harvest during the coldest time of year here (over a month of never-above-freezing temps, with a low of -25F) and this passive greenhouse never froze. The tomatoes and broccoli grew over 5 feet tall, the ladybugs are reproducing and the bees are pollenating. Crazy! It is a simple tire-bale earthship-style thermal mass greenhouse. I am making videos of a step-by-step build, we are getting close to finishing. That will have to be another post. But here is a video of the temps over winter, and also of a harvest in the late winter. Yum! Hope you enjoy!

great video, would love to see an update on the greenhouse posted!

This is awesome, and exciting to ponder, but unfortunately we are probably too far north (lat 60) for it to work all winter. Even with supplemental heat there's just not enough sun in dec/jan for anything to really grow. But, I think it's still worth doing to get a jump on spring and extend summer. (We would probably go with earth bags or berms to avoid the potential contamination from a petroleum based mass). Thanks for sharing the video!

Here is an update after using the Thermal Mass Greenhouse (TMG) for about 2 years... has never frozen inside, lowest temps over this winter ('22-'23) were in 40's F, even when without sun for 2-3 days. Don't forget these type of buildings gain heat from not just SOLAR gain but EARTH gain.

Do you have a video or an explanation of how you built this?  Did you use cob?
I have read the books put out by Cerce, but have trouble understanding some of the jargon.  I need a contractor, but none in my area have built passive solar.

Hi Eric,

I would love to know what you're using to record your temps.  

I have been using RC-5 remote data loggers but I'm not sure if this is the best method.  They don't use wifi and I have to manually collect them, plug them into my computer, and use an application to get graphs. http://www.elitechlog.com/rc-5usb-temperature-data-logger/   -  I had two but just bought 3 more on ebay (used) for $30 (for all 3)

I would also love to know if you've thought about capturing the warm air at the top of your greenhouse and pushing it through the soil like a climate battery, or if you feel it's warm enough on it's own.  I am in Colorado at 7,800' so this is helpful for me!

thanks