One of the fall projects I have worked on is creating a completely solar greenhouse. I built this right over my moso bicolor so I can protect it as well as speed up its growth. I'm also using it to place some of my bamboos so they can grow a bit more through the winter. My objective is to insulate it well enough so that additional heating will not be necessary here in zone 6a. At this time of the year, the greenhouse typically raised the greenhouse about 5-20F, but those numbers typically increase in the middle of the winter.
Here's the outside of it.
This may not make sense, but I placed the door on the west side where the wind blows into it, but over the winter, there will be an entire tarp that goes over the greenhouse partially so that the wind and snow drift does not pile onto the door. It will also make it much easier to get inside when there's a lot of snow.
The solar vent was added yesterday to help with the air flow as carbon dioxide can be depleted with all the plants in the greenhouse. It works well because it only turns on when the sun is shining strong enough which also means that the plants will be photosynthesizing. That's when they actually need more air flow. I placed it on the south side of the greenhouse at a 45 degree angle to make sure it is functional.
Here are my 55 gallon drums for the heat sink. I am using black colored drums on purpose so that they can absorb more heat which can keep the greenhouse warmer through the night. I can also stick a fish tank heater in one of these which should be enough to keep the greenhouse above freezing however it will also make it even more humid than it already is.
Right behind the heat sink on the north side of the greenhouse, I already have reflective bubble wrap to help provide more insulation. It can also help reflect light back onto the plants. It's reflective capabilities should also help heat the greenhouse up a little bit more.
Here's the shelves that came with the greenhouse kit. I plan on using it to place either a small heater, a 400 watt metal halide, humidifier, paraffin lamp, or any heating device that will be enough to keep the greenhouse from freezing over.
Here are the 2 shoots on my bambusa ventricosa which have gained about 2ft of height after 3 days of being inside the greenhouse.
Finally here's the moso bicolor
30 Sept 2012: I decided to add a 4th 55 gallon barrel to the greenhouse, and it has been tarped on the north and west side so there is more insulation. It also allows the wind to blow over the greenhouse much easier instead of radiating too much cold air inside. I've noticed that north and west facing windows are more likely to have cold air radiate in so I'm providing extra insulation on that side.
Many more leaf filled bags will be stacked up on the north side to help provide even more insulation.