I have built a 10'x10' greenhouse from scrap wood ,plastic ,old storm windows ,and corrugated barn tin! T he tin is around the bottom perimeter, from the ground ,up to around 30" or so. Its attached to the outside. could I paint it black, inside and out,attach more on the inside(painted black also) ,leaving an air space vented at the top of the tin,to generate heat to keep plants from freezing on really cold days? could i fill it with some medium to collect the solar heat and release it slowly at night
If we could find a way to heat greenhouses all winter so they never froze and do it for little money, we could solve the worlds hunger problems. I have been working on this issue for many years. I have a 20' x 30' hoop house and I can grow food all winter, but not much when it is wicked cold and the days are really short.
A single layer of black painted tin on the south side will increase the solar gain a little. I use black barrels inside my greenhouse that are filled with a non-toxic antifreeze. The barrels get warmed whenever it is sunny and they hold heat for night time heating. Unfortunately, if there are many days with no sun, it will get cold in the greenhouse.
I suggest looking at plants for the winter that are very hardy. Elliot Coleman has a book out that is about winter time greenhouse use, and I suggest you get a copy and see what he is doing.
Greetings. I am currently building a Passive Solar Room Greenhouse Addition which will convert our home into a Passive Solar Home and provide fee heat on sunny winter days, yet stays cool in the summer.
I will be posting about a hundred You Tubes on how to do this step by step. https://www.youtube.com/user/WoodyChain https://www.youtube.com/watch?v=BBgrP53kT-w&list=UUQEFQJGOpz38hEQiQX8cJKA&index=50 Here are some pictures that will give you some idea of what were doing.
I have learned that attaching a greenhouse to a living space and actually growing food on a scale large enough to feed a family, can become a problem with fungus and things invading the living space, so this will be my new office and our solar greenhouse will be further away from the house and wont be attached.
Build the solar room as a free standing structure instead of a lean to, is quick and easy with this design, yet will handle a huge snow load, like we receive up here in "The Yaak", MT.
I hope this helps.
The trick to a solar greenhouse, is to have all sides of the structure insulated other than the one side that is exposed to sun (the south side if you are in the northern hemisphere). I used 2" rigid foam insulation panels. Then you want your glazing set perpendicular to the average angle of the sun in winter. This is generally going to be equal to your latitude. I live in Seattle, so 45º, which is close enough to 47º, worked for me. If you can afford double glazed windows you will be better off than with single pane windows, but it can work either way. For heat retention, you'll want to have lots of thermal mass in the greenhouse. I use 55 gallon metal barells panted black and filled with water.