Geothermal greenhouse

Deub

I watched some videos about geothermal greenhouses. The idea is to use to warm air produced by the greenhouse during the day, and store it underground to release it during the night. It is essentially usIng the earth as battery.

The most painful part in the building process, is to dig to place the pipes.

Does anybody know if someone has done it here?
I am curious to know what are the results.

Here are some videos (series) about it:

Jim_Hodge

As I understand it an electric heat pump runs almost constantly - proves to be expensive.

Deub

Jim_Hodge wrote: »

As I understand it an electric heat pump runs almost constantly - proves to be expensive.

It is fans pushing the air through the pipes. There is no system heating the air.
I was searching for solutions to keep a greenhouse warmer than outside during the night and I saw heating systems which, indeed, seem expensive to use.

macraignil

Have been offered some second hand windows that I am going to use to build one when I can get them delivered so no direct experience with this idea yet. I was doing a bit of research and found this video had some good information.

Deub

macraignil wrote: »

Have been offered some second hand windows that I am going to use to build one when I can get them delivered so no direct experience with this idea yet. I was doing a bit of research and found this video had some good information.

Thanks for the video. The system I am talking in the OP is GAHT ( ground to air heat transfer). It seems to be a heating system for cold period and a cooling system for warm period.

macraignil

Deub wrote: »

Thanks for the video. The system I am talking in the OP is GAHT ( ground to air heat transfer). It seems to be a heating system for cold period and a cooling system for warm period.

No worry. It sounds like an interesting project so its good to share as much information as possible. My own planned design has less glass area than the types in the videos you posted and I reckon I will not need to worry too much about the cooling element of the system if I follow the current version I have in mind.


I'm thinking of trying something in that GAHT category as well. I even drew out a rough design for what I might build after watching the video I put up a link to. The offer I have got of the old house windows has been made since then by a neighbour who I talked to about my idea and knows someone who wants to get rid of them but I think they give me the opportunity to build something that is very insulated for an affordable price. I have yet to get these windows but they look in the picture I have seen like they are double glazed glass which should work better at keeping the heat in than the materials I would have had to work with if I was getting everything in new. The windows I hope to place mainly on the south facing side with some on the east and west sides as well but thinking the north facing side will be a block wall that I will paint black to be the main solar thermal absorption area. Got to get the dimensions of the windows before doing any more design work but will also have to organise a draft proof door which I might also try to find second hand.



Currently looking at just having a flat roof with more of an emphasis on insulation than letting light through as the video explains a lot of the sun in the winter is from a south direction and not directly overhead. North facing glass would be of little use. What I'm going to build may end up looking more like a potting shed than a greenhouse. Might also include a tank for keeping fish in my system as I think it is a neat idea to have the fish tank water to provide fertilizer for the plants. The water in this would also be a thermal storage device. Would be hoping to build the whole thing to be warm enough to keep tilapia which can survive down to 9 degrees celsius but will need to test the setup with some goldfish first to see if it can stay warm enough.

Deub

Using the water tank as a storage heater is a great idea. If you can also use it as fertiliser, even better.
The type of roof will mainly depend of the width of your greenhouse and what you plan on growing. If it is vegetable, you could do a lean to roof facing south. It would provide more heat and light.