Introduction: Geodesic Dome Greenhouse
Hello! Hello! We are from YES-2-Tech, part of a program called Youth Exploring Science (YES) at the Saint Louis Science Center, funded by the National Science Foundation as part of their ITEST program (Information Technology Experiences for Students and Teachers). The YES Program is dedicated to providing the opportunity for teens who face multiple risk factors to learn job, school and life skills. As YES-2-Tech Teens, we teach math and science skills to community youth, design and build geodesic dome greenhouses, work with technology and other activities. In addition, we give presentations to large companies to explain them the purpose and progress of the YES Program.
For more information about the YES program please visit www.youthexploringscience.com.
Working and building the domes has been exciting, but also very beneficial. We traveled around St. Louis teaching kids and adults about the purpose and functions of the greenhouses. Also, we supervised the building of domes at different community centers. With a geodesic dome greenhouse, you can extend the growing season of your plants and protect them from the harsh weather outside.
Greenhouses and how they work:
Here's what we learned about why our dome (and other greenhouses) help plants live for a longer season:
Plants germinate (sprout) from seeds and grow through their life cycle depending on light and soil temperature. We couldn't do much about how much the sun was shining, but our dome made the air, and the soil in the dome warmer than outside the dome. From what we saw, it seems that growing season depends more on soil temperature than light, because some of our tougher plants like cabbage and lettuce kept growing in our dome most of the winter. They slowed down a lot, though.
But we wanted to know, why is it so hot inside??? We can tell a difference when we step inside right away, even though the plastic is not that thick. It's much warmer and the air feels sticky sometimes. It feels really nasty in there sometimes in the summer. There are 2 main things that our dome does to help the temperature stay warmer than the outside air.
1. The air inside the dome is separated from the air outside of the dome.
2. The clear (or semi-clear) skin lets light energy in, but traps heat energy.
Even though our dome skin is thin, it keeps the air inside the dome from mixing with the outside air when the wind blows, or a bus drives by. When the sun shines on the dome, lots of the high-energy light can come through the skin. Light goes through space in waves, and the light that helps us see can go right through clear objects, like glass or our dome skin. When the light bounces off the ground inside the dome and plants and the tools, it loses some of its energy. That means that the waves that bounce off can't move as fast as the waves that came into the dome, and they get trapped inside the skin. So while the sun shines, the dome gets hotter and hotter as the energy from the sun gets trapped. And this hot air can't mix with all the other air outside, and level out. That's why it feels so different in the dome. We feel it right away. It's nice in the wintertime, but when it gets hot, we start sweating right away when we walk in.
At night, when it is colder, the air in the dome has to cool off before the ground can start getting colder. We buried a digital light and temperature reader in the middle of our dome, and also hung one up in the air on a string using a pipe cleaner to make a hook. We noticed that the air got colder, then the ground got colder. Also, when the air warmed up, the ground got warmer too.
The hotter air in the dome also means that the air is more humid. Humidity means that there is more water in the air, and it can make it seem even hotter than the real temperature. That's why we seal the wood for the dome real carefully. All the water in the air can make the wood get moldy and rot. When we open our vent flaps all the way, it gets cooler fast. The hot air rises out of the vents, and mixes with the outside air. The water in the air also leaves too, and it feels much better in there. We always see little drops of water by the vents when they are closed. That's because the water comes out of the air when it is near the colder air.
Last thing: We want to warn people who think they can grow anything they want all year round. You can try, but you will end up killing a lot of plants (like we did in our first year dome). There are plants that are good for planting in the cold season, like all the plants in the cabbage family. Their family name is Arabidopsis, so if a plant has that in its scientific name, it is probably good for putting in your dome in the fall.
If you decide to use our instructable and make your own dome, we want to know what you planted!!!!! We grow food for people who can't always buy food on their own. We also go to different community groups and build new domes for them. We are getting pretty good at making these, which is why we thought we would share our experience with everybody. How hot does your dome get? What did you add to make our dome even better? Please let us know.
YES-2-Tech Teens from the Youth Exploring Science Program
Step 1: Materials Needed
40 pieces of 1" x 2" x 8' wood
1 gallon waterproof sealant
10 6' flat perforated metal straps
25 coarse thread bolts 1/4" diameter x 3/4" length
25 1/4" hex nuts
For putting everything together:
250 1-1/4" drywall screws
250 #8 washers
box of 10' x 100' 6 mil plastic sheeting
2000 5/16" staples that fit your staple gun
For rebar bender:
4' x 6" x 6" piece of wood
4 spikes or large bolts
4' piece of 3/4" plumbing pipe or conduit
2"-3" general purpose paint brushes
hand wood saw
bench vise (used to bend metal strap)
drill hammer (baby sledge)
2 socket wrench sets
Phillips screwdriver drill bit
set of multi-sized drill bits
Step 2: Clearing the Ground
In the location in which you intend to place your dome, clear the ground by removing all grass from an area that is 12' in diameter.
Step 3: Cutting the Wood
1) Start by measuring and cutting 30 pieces of wood that are 42" in length. These are your "A" pieces. It would be good to mark them with the letter A.
2) Once you have those pieces cut, measure and cut 35 pieces of wood that are 48" in length. These are your "B" pieces. Mark these with the letter B.
Step 4: Weatherproofing the Wood
After cutting the wood, use paintbrushes to coat it with the waterproof sealant. Allow it to sit overnight or until dry.
Step 5: Making the Connectors
When you are finished, you will have 10 4-way connectors, 6 5-way connectors, and 9 6-way connectors.
1) Begin by cutting ten strips that have ten holes each.
2) Next cut twenty strips that have seven holes each.
3) Once you have all of your strips cut, you will use a vise to bend the pieces. Each bend should be approximately a 25 degree angle. On the strips that have ten holes, bend them twice, at the fourth hole from each end. Do this for all ten strips. For the seven-hole strips, bend them once, at the second hole from one end.
4) Once you have all of the pieces bent, you will assemble them. Attach two of the seven-hole strips to the middle (fifth hole from either side) of the ten-hole strips. Place the seven-hole strips on top of each other. Then, using a bolt and a nut, connect them together. You do not need to fully tighten the bolts at this time.
5) Repeat step four until you have a total of ten connectors.
Step 6: 5-Way Connectors
1) Begin by cutting thirty strips that have seven holes each.
2) Once you have all of these strips cut, use a vise to bend the pieces after the first hole from one end. Make 25 degree angles on all bends. You must do this for all thirty strips.
3) Once all of your strips have been bent, it is time to assemble them. Line up the first hole for five of the strips and connect them with a bolt and nut. For assistance on how they should be assembled, refer to the picture.
4) Repeat step three until you have a total of six connectors.
Step 7: 6-Way Connectors
1) For the 6-way connectors you will need to cut twenty-seven strips that have thirteen holes each.
2) Once you have all of the strips cut, you need to bend them using a 25 degree angle. Bend at the fourth hole from each end (leaves five holes in center space). You will bend each strip twice. Do this for all of the strips.
3) Assemble them by connecting them at the center hole (the seventh hole) with a nut and a bolt. Do this for all nine of the connectors. Once you have all of these steps completed, you are finished fabricating the connectors.
Step 8: Make the Pentagons
Using your drill with a screwdriver attachment, fasten one arm of a 5-way connector to a 42" (A) piece of wood using two screws (with the washer around each of the screws). Look at the picture below for the placement the screws. Once you have your first "A" piece of wood attached, you will repeat this step for the remaining four arms of the 5-way connector. Repeat for all five 5-way connectors.
Step 9: Adding the 4-way Connectors
Next you will attach two 4-way connectors to the assembled 5-way connectors and A pieces. Put a washer around the screw (two screws go in each leg), then attach one 4-way connector to one leg at the bottom of the pentagon and attach the other 4-way connector to the other leg at the bottom. For more help, look at the diagram below.
Step 10: Adding the 6-way Connectors
Next you will attach two 6-way connectors. Put a washer around the screw (two screws go on each leg) then attach one arm of one 6-way connector to the top of "A" piece of the pentagon and another 6-way connector to the left "A" piece of the pentagon. There will be one "A" piece that does not have a connector. The diagram shows the placement of the 6-way connectors.
Step 11: Attaching the "B" Pieces
Attach one 48" "B" piece of wood between each outside connector. Be sure to install two screws and washers for each piece of wood. For more help, see the diagram. There will be no connector on one of the corners of the pentagon.
Step 12: Finish the Pentagons
Repeat the previous few steps to complete the other four pentagons. You will have 5 pentagons when you are done.
Step 13: Connect the Pentagons
To connect the pentagons to each other, connect the 6-way connector on the left side of the pentagon to the right side of another pentagon without a 6-way connector. Repeat all the way around until each pentagon is connected. There will be ten "A" pieces connected around the middle of the pentagons.
Step 14: Connect the Bottom of the Pentagon
Now attach "B" pieces between each pentagon at the bottom of the dome using the two 4-way connectors. Repeat until there are ten sides on the bottom of the dome.
Step 15: Connect the Top of the Pentagon
At the top of the pentagons, attach a "B" piece to the 6-way connectors between each pentagon. Repeat until the five "B" pieces connected at the top of each pentagon form a pentagon.
Step 16: Preparing to Make the Roof
First, pick a pentagon most convenient to where you want your door. Then disconnect the 5 internal legs ("A" pieces) with the 5-way connector from the external connectors (4- and 6-way) on each leg. The five legs that are disconnected will remain attached to a 5-way connector and make a star shape. This will be used to make the roof and the open pentagon will be used to make the door.
Step 17: Attaching the Roof
Connect the ends of the legs to the last available 6-way connectors at the top of the dome to form the roof.
Step 18: Tighten All the Connectors
Put one socket wrench on the nut side and one socket wrench on the bolt and tighten up all of the connectors on the dome.
Step 19: Making the Door Frame
Since there are variables that affect the exact dimensions of your completed dome, making the door is a field-engineering task. Measure a piece of wood that will be use to construct the side of the door. Start at the bottom corner of the open pentagon where the 4-way connector is and go straight up until you are touching the top leg of the open pentagon. Mark the wood were it touches the top leg pf the pentagon (see photo below). Repeat this step on the other side.
Step 20: Connect the Door Frame to the Dome
After you mark the piece of wood, cut it at an angle so that it fits the pentagon flush against the top piece of wood. Attach the cut piece to the 4-way connector at the bottom of the pentagon. Use a 3" screw to attach the piece of wood from the top of the pentagon where it fits against the wood. This will hold your door frame together. Repeat this step on the other side.
Step 21: Adding the Top of the Door Frame
Next, measure another piece of wood to create the top part of the door. To do this, hold a piece of wood at right angles to the tops of your two parallel door pieces. Mark the spots that will allow you to connect it to the "B" pieces of wood at the top of the pentagon. From the outside of the pentagon, use 3" screws to attach this piece where it fits against the top of the pentagon and the other door pieces.
Step 22: Adding the Side Supports
Next, measure a piece of wood that goes from the 6-way connector at the side of the pentagon to the piece of wood that makes one side of the door (see photo below). Screw the piece of wood into the connector and into the piece of wood that it touches. This step adds support to the door. Repeat this step on the other side of door.
Step 23: Adding the Top Support for the Door
The last step of constructing the door is to measure a piece of wood from the top 6-way connector to the top part of the door, cut it and attach the wood to the connector and the door (see photos below).
Step 24: Make a Rebar Bender
Now it time to anchor your dome to the 12' X 12' area where you have cleared the grass. You will use twenty pieces of bent rebar to anchor your dome into the ground.
To see a visual of how to make a rebar bender (jig) and bend the rebar to hold down the dome, visit this website:
Step 25: Anchor the Dome to the Ground
With your drill hammer (small sledge hammer), hammer two pieces of rebar over each "B" piece into the ground. There are ten sides to the bottom of the dome, so you will use twenty pieces of rebar to hold it down.
Step 26: Cover the Dome With Plastic
Cut out a large sheet of plastic, about 6 to 7 feet long. Cover a section of the dome with the plastic. Start from the bottom and work your way up. See photos below.
Step 27: Staple Plastic and Cut Off Extra Plastic
Pull the plastic tight over one triangular section of the dome. Staple just enough to attach the plastic to the wood on each leg of the triangle. Then go back and staple the plastic to each leg of the triangle, stapling about two inches apart. As you do this, continue to smooth the plastic to get the wrinkles out. It helps to fold the excess plastic on top of itself as you staple it onto the wood. Continue by covering as many triangles as you can until you have used up the plastic sheet. When your first section of plastic is securely attached, cut off any excess that does not completely cover a triangular section of the dome.
Step 28: Keep Adding Plastic Until Finished
Repeat the process until the dome is covered. You will need to put a ladder inside the dome to staple the plastic onto some of the top parts (see photo).
Step 29: Add the Vent
You'll most likely need a ladder inside the dome for this step. Place the ladder on the ground under the top of the dome. Cut along one leg of any triangle at top of the dome (see photo). This will create a vent that will allow air to circulate and help regulate the temperature in your geodesic dome greenhouse.
Step 30: Make the Plastic Door
To make the plastic door area for the dome, put a sheet of plastic on the door frame, cut it through the middle into two symmetrical halves, staple the plastic onto the frame, then trim the excess plastic hanging from the frame.
Step 31: All Done!
The completed dome