Backyard Aquaponics
A place to discuss aquaponics

At the end of summer, I built a 6.4 m geodesic dome (2V), using the Zip-Tie Domes system. http://ziptiedomes.com For those of you who are unfamiliar with this method, the dome is constructed using 1 inch (25 mm) PVC piping, connected to 4 inch (100 mm) PVC hubs using 125 lb (56 kg) vinyl zip ties. The dome is covered by greenhouse polyvinyl that I've pleated and fastened under the edge using aluminum fabric clips. My family and I are very happy with the greenhouse, but we are running into temperature problems now. See pics below...

Throughout the fall and winter, the temperature has not been a huge problem, though we have no formal ventilation system in place. Now, temperatures can easily top 45°C if I don't open up the front of the dome during the daytime. If I am lucky, I can keep it below 30°C. In short, it is time to install a proper ventilation system that is responsive to temperatures within the dome. I would like to know from the members if they have ever worked with this kind of greenhouse and solved ventilation problems. Thanks for any insights you can provide.

No advice,just a very nice dome.Are you in snow country?

I'm in San Jose, California. We never see snow here. The temperature never really drops below freezing, so this is a single-walled greenhouse covering. During the colder months, I have issues with condensation, but the vinyl is designed not to allow dripping onto the plants. Rather, any condensation just rolls down to the bottom where it can drain.

Possibly frame in a couple sections like web4deb did?Familiar with your area,thanks for sharing this system,Ive already passed it along to a couple friends.We are down by lake arrowhead/big bear area at 5000 feet.

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I would just use poly tape the plastic to the pvc section at the top, and then cut out a section to vent the hot air. Add a few feet on the bottom for a side curtain if you need more air movement. You have to have air movement, or you'll end up with loads of disease problems. Still air with lots of humidity not your friend.

Following up on the problem of ventilation in the dome greenhouse, I have opted to install an attic fan at the top, while adding zippered slits along the first tier. The first day running was almost perfect. There was a time during the late afternoon when the fan was running nonstop, and the temperature got up around 90°F (32°C). More slits should do the trick.

Make sure the outside of the fan doesn't get rain in it. They are designed to be installed on gable ends where they are protected from rain.

This one has a hood. It's designed to be installed on a sloped roof of anywhere between 45 and 25°, but I know the type you're talking about.

One challenge is that you are supposed to install it with the hood not peeking above the ridge-line of the roof. In the case of a geodesic dome, there is no ridge-line. They're worried about strong gusts going under the edge of the hood. Will have to see how that plays out.