Underground Greenhouse vs. Earth Tubes

Still debating on the design of my greenhouse and whether I want to use earth tubes to warm/cool an above ground greenhouse or build an underground greenhouse.

I love the idea of underground but concrete walls are really expensive and earthbag walls would take forever given the state of my body. Plus I don't like the fact that the further you go down the less light you are going to get esp in the winter. Half of your floor space could be shaded which means you would probably want to grow on benches. If you want to grow fruit/nut trees, I guess it wouldn't matter.

I'm just not sure if I can get the same amount of heat from earth tubes.

What's your pick and why?

Why not use both ?
You could use reclaimed bricks to build the walls, that is much more inexpensive.
Plus i think heat is more important then light during winter especialy if there is a chance of sub 0 temp.

Underground probably has the biggest impact.
The way the sun shines on your location and water table depth should make the decision for you. If you have a south facing slope, go underground.

Check this out. Earth air exchange tubes, partially in the ground, no earth bags, no concrete.

http://www.citrusinthesnow.com/

http://youtu.be/LnYC_7CDmlo

Thanks for the feedback everyone. Because of cost and the complexities involved with going underground, I'm just going with the earth tubes. I really don't think both (underground and earth tubes) are necessary since the greenhouse is only going to be 120 sq ft and its going to be attached to the south side of my house. My porch on the south side rarely freezes so I'm hoping the earth tubes will keep the greenhouse in the 40's even when its really cold. It was zero last night and it only got down into the low 30's on the porch and the south wall is all glass. I have to admit, I'm really not sure if a 10 degree boost from the earth tubes in winter is realistic though.

Bill J Price wrote:Check this out. Earth air exchange tubes, partially in the ground, no earth bags, no concrete.

http://www.citrusinthesnow.com/

http://youtu.be/LnYC_7CDmlo

I'm familiar with Russ Finch. I bought his report. And while I don't recommend others buying it, what he's doing is amazing.

Its awesome that he's got very stable soil so he doesn't need retaining walls but I've got beach sand so I would definitely need them.

Paul, if you add your climate zone it would help us give appropriate advice.

Where I live, high cold desert, we heat our houses solely with attached greenhouses on the south wall. We remove the greenhouses in May and put them back on in October. I love it. This time of year when there's dreary melting snow and no greenery outside, I spend a good amount of every morning in my attached greenhouse mooning over some new germination, or growing salad greens, or swelling flower buds. Yay! However, every year in late March it gets roasting hot in there some days if we don't remember to open a ventilation option. And by May it starts to get too hot even with some ventilation, so we remove the greenhouse, and all summer we have normal houses, nice and cool.

The only time we made an underground (freestanding) greenhouse, on the strong recommendation of the local army labs, we abandoned it after one year. Sure, the attached greenhouse goes below freezing on winter nights, but many kinds of plants don't mind that, and it protects our houses so their south wall is exposed to a few degrees below freezing, not tens of degrees below freezing like the outdoors. In rare instances when we had delicate things or were trying to keep things growing through the winter instead of going dormant, we put on additional covers (made of old worn out greenhouse film) at nights. But many things do fine through the winter without that protection, and don't mind a few degrees of frost.

We have neither fans for summer nor backup heaters for winter.

A lot depends on your location and zone. If you are so far north that the winter sun is negligible, underground makes sense. If, like me, you've got plenty of winter sun but cold air, an attached greenhouse, unshaded by the ground, is wonderful.

Hi Rebecca,

Thanks for your response. I'm in zone 5 near Chicago. So yes, the winter sun is sparse.

So you abandoned the underground greenhouse because of shading?

I was looking at a floor plan and realized since its only a 120 sq ft greenhouse, if I went underground, stairs (up to code) would use over 20%!!! (25 sq ft) of usable floor space since I'll definitely want 2 entrances, one from the house and one from outside. You really have to look at so many factors.

We abandoned our underground greenhouse for a couple of reasons. One main one was the shading -- the south wall shaded a good portion of the greenhouse from the low winter sun. Another problem was our basic design, which meant that to go inside (to weed, water or harvest) we had to loosen one corner of the film on top and crouch in. Not very convenient, and it seemed like it was losing heat any time we opened it. Your underground greenhouse doesn't have to have this problem.

im from Slovakia and thinking to build party underground geodesic greenhouse, so the floor will be ~40cm under.. and probably will add pipes
what do you think?