13 Creating a Greenhouse out of Electric Metallic Tubing EMT

Picture of EMT frame, draped with plastic
So how do you grow 365 days a year when you have cold winters? A greenhouse is a big part of that answer. [In fairness, 365 Aquaponics also requires attention to fish selection and plant choice, but that’s for another post.]

The lightbulb went off for me when I saw a video of Michelle Obama’s hoop house garden, at the White House. An evening of internet surfing later, I knew all kinds of information about high tunnels, aka hoop houses.

But a standard hoop house wouldn’t work for me. The typical cross section of a hoop house is a circular arc, 12 feet wide if it’s 6 feet high. Not bad for crops grown in the ground, but murder if my crops are sprouting 3 feet above ground level, as in an aquaponics system that’s wholly installed above the surface of the ground. Besides, all that area at the edges is practically useless for either growing plants or allowing the gardener to walk around.

There are some nice greenhouses available for sale. Harbor Freight has an inexpensive 10’x12’ model that is used by many gardeners. But my townhome community has covenants that limit how tall my backyard structures can stand.

Besides, I wanted to see if I could come up with a sturdy greenhouse someone could build themselves from standard materials available at local hardware stores.

Now that I’ve lived with such a greenhouse for a summer, I prefer a simple hoop house over standard greenhouses. When it gets hot, you can simply remove the plastic from the hoop house for the hot months. If you need shade, drape shade cloth over the hoops. Nature takes care of ventilation and pollination. When the days and nights start cooling, put up the plastic again. 6 mil plastic will be stronger and provide better insulation, but 3 mil plastic lets in more light and still keeps things moderately toasty in the sun.

I used Electric Metallic Tubing (EMT) rather than the more typical PVC pipe because:

• EMT allows me to achieve a precise shape
• EMT is stronger
• EMT won’t break down under UV sunlight the way unpainted PVC does.
• EMT is sold in 10 foot lengths, allowing me to create an arched form that is 8.5 feet wide and around 7 feet tall from just two 10 foot lengths

Pictures (better, moving pictures) are worth thousands of words, so here is a movie showing how to set this up.

N.B. - If your plant roots are "dark," this may be due to particles in the water youre piping in under your floating raft. In that case, consider adding some kind of filtration to reduce the particulate content.

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Starting the Rocket Mass Heater

Today I finished building and fired up the rocket mass heater for the geodesic dome. Ironically, its January and were having record breaking warm temperatures in the 50s but I couldnt resist and started it up. I will do a full video about the construction in the future, but wanted to share a few pictures of it. This heater is a bit different than some you may see. I wanted to be sure there was enough drafting in the chimney so I doubled up the barrels.

The entire burn tunnel is buried under the floor. It took a little while to get the drafting to start. It didnt help that the internal chimney wasnt insulated yet (missing some parts for it), but once the system got warmed up, it turned into a raging inferno.

A picture without the flash shows how well the fuel is burning in the tunnel.

I ran out of sand so I wasnt able to completely bury the horizontal exhaust. It was quite hot to the touch, but as you moved down the pipe, I could hold my hand against the duct and it was slightly warm.  It was quite funny to see the sand around the duct drying out so quickly. It will be interesting to study the temperatures along the system in the future!

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