We started the long process of building our Geothermal Geodesic Dome Greenhouse in the Fall of 2016. It has been a long process because other than a few days of friends and family helping with the Geothermal battery and foundation, most of the work was done by just the two of us when weather would allow.
Too much wind, you can’t install Lexan or Stucco. Too cold you can’t glue Lexan or Stucco, so weather really had a lot to say about when we got to work.
But finally, the Greenhouse is up and the Lexan is all installed. The stucco still needs the finish coat, but that will be easy and Spring is almost here! We still have to make window frames, install one more door and have a few other projects (like a loft inside the dome on the North wall) that we want to do.
I did plant lettuce mix, spinach and radishes in barrels and then we put a temporary hoop-house over them inside the Dome to see if we could get an early start and have some more freshness for our Farmstand Delivery service. SUCCESS!! We had -7 degrees F here the last week of February and even though we still had some Lexan missing and NO HEAT source other than the Geothermal battery, the temperature stayed above 40 degrees F in the hoop-house. This was wonderful for a couple of reasons.
- It really takes a year of the greenhouse being up and closed in for the Geothermal Battery to build up some good temperatures, it has only been a couple of months of semi-closed up.
- We did NOT add any other heat source.
I had seen a post on a Facebook group asking about different ways to heat the greenhouse and when I posted Geothermal, I got some wacky responses. I still believe this is a worthwhile way to go. Yes, we will have to add in some heat from a woodburning stove if we want to keep the greenhouse at optimal temperatures in the winter to grow goodness, but it will be much less wood (or propane, natural gas, electric) to heat from 40 degrees F to 60 degrees, than it will be to heat from -7 degrees.
In the summer months, the Geothermal battery will help to bring the temperatures down from 100 degrees to 60-70 degrees without a cooler. The temperatures of the Geothermal battery by the mere fact that is buried underground will not reach severe highs nor lows. A simple solar fan blowing through the inlet and outlet tubes move the air through the battery. Warm air from the upper level of the dome is blown down warming the battery from the normal earth temperature of 40 degrees to about 60 degrees (after about a year remember). Anyway this will moderate the temperatures in the Greenhouse requiring much less input from other heat and cooling sources. So the expense of building the Geothermal battery will pay for itself easily.
We didn’t just jump into this without research. We have been building and loving our Geodesic Greenhouses for 12 years now and Central Rocky Mountain Permaculture Institute is the place we got the idea to add the Geothermal as they had already had one in use for about 5 years when we found out about them. We did hire their engineer and had plans for the battery drawn up taking into account our own unique situation/location.
I have heard of someone having a problem with mildew and condensation build up in the underground tubing, but I would have to believe they live in a very humid climate and did not use slotted tubing to allow the moisture an escape route. You probably shouldn’t build it in a swampy area either without making allowances and protections from seepage. In the Northern Colorado Mountains that is not a problem.
You can view the videos that we made along the process of building our Greenhouse at our Youtube Channel: Genesa Garden