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View Full Version : Solar Kiln from old casement windows?



Mark Greenbaum
09-17-2015, 9:35 AM
I am getting ready to remove and replace 20 casement windows for our new 40 year old house. I hate to just dump them, so I've thought perhaps of repurposing them into a solar kiln/greenhouse in the backyard. Has anyone on the forum done this? If so post your pictures and let me know some of your ideas.

I envision a 45 degree window wall facing south, with an overhang at the base. In the overhang placing soffit venting to allow cool air into the structure. At the peak having ridge venting to allow excess heat out. The greenhouse idea would be to allow the condensation and water vapor from the drying wood to be usefully absorbed, and to moderate the temperatures.

What thinks y'all.

Thanks.

Cody Colston
09-17-2015, 9:45 AM
Glass makes a very good solar panel with one caveat...it breaks. Even at a 45 degree angle, it will be exposed to hail damage. I do like the idea of re-purposing the windows, though.

Soffit and ridge venting will certainly remove the moisture but you need some way to control the venting process so that you can regulate the heat. Solar kilns always have a trade-off between heat vs venting. I would recommend you take a look at the Virginia Tech solar kiln design that has adjustable vents and fans for air flow through the stack. If the air doesn't circulate through the stack, the wood will mildew and stain badly, especially light-colored species.

Art Mann
09-17-2015, 9:57 AM
Casement windows mounted on a 45 degree angle will leak profusely and rot quickly, if made of wood. A kiln and a greenhouse are at cross purposes. With a kiln, the idea is to expel the evaporating moisture quickly with powered or passive ventilation while sustaining a temperature that is well above what is healthy for plants. Greenhouses need to be maintained at high humidity level. If you don't use pressure treated or highly moisture resistant lumber, structures inside a greenhouse will mold and rot very quickly. I am sorry to be negative, but I really believe this is a bad idea.

Mark Greenbaum
09-17-2015, 10:06 AM
OK - if I place all of the windows vertically and just go for the solar kiln aspects, can it be done with single pane glass windows?

Jim Andrew
10-25-2015, 10:59 AM
Vertical glass will work in winter when the sun is at it's southern most level. Put a small room dehumidifier inside the kiln so you don't have to vent the moisture out.

Brice Rogers
10-29-2015, 5:02 PM
I built a greenhouse about 10 years ago using sliding glass patio doors. I suspect that all were tempered. The north wall is plywood but the other sides are either patio glass or a storm door. On the roof I put three large patio glass doors. They are probably at a 20 or 30 degree angle to the horizontal. We've had some big hail a few times and they lived through it. So if the OP has any tempered glass, I suspect that they will easily live through most hail storms.

Because it is a greenhouse, excess heat is an issue that needs to be addressed. I have a 10 square foot panel on the north wall that opens with a (thermal expanding) wax-filled piston. They are available from Charlie's Greenhouse supply or from Harbor freight. They don't require any power other than heat from the sun. I also have a thermostatic controlled AC fan that comes on when it really gets hot. I don't know if excess heat is an issue with a kiln. In fact, maybe heat is a good thing.