Monday, February 07, 2011

Heating a green house without using “energy” . . .

Sources of information . . .

Start with thermal mass:
We use barrels filled with water:

Add a compost pile for some supplemental heat: He is talking about keeping the temperature above freezing most of the time. However, I grow many winter crops in temperatures down into the low teens. If you adjust what you expect to grow in the green house, you don’t need to keep it very warm.

Add animals for even more free supplemental heat:
These folks are using some high tech options—but I have read about this being done in a much simpler fashion. Your animals will need ample water, and a way to freely leave the green house during the day—because the solar gain can be enough to cook them. When it is 50 degrees outside on a sunny day, our greenhouse here can be over 120 degrees.

Not only can you heat your green house for free—you can use the heat the greenhouse collects to heat your home. On sunny days that works for the main farm house here, without any major retrofitting at all. The green house is simply bolted to the main house.

But if you want to get fancy, check out what these people have done:

Hot Beds are also useful ways to heat green houses and hoop houses. They utilize manure, usually horse or cow, in deep trenches over which you plant your crops. They provide heat to the soil and roots, with some escaping into the air:

You are also going to need vents and vent openers--unless you are going to monitor your green house all day every day. On 50 degree days here, our green house can be over 120 degrees! Here is a company that offers some solar powered automatic vent openers: I am not recommending this company, I am just recommending that you design your green house with vents and have some sort of vent openers. Since we are talking no energy use here--solar ones seem like the way to go.

Here are some book recommendations for those who would like to know even more . . .

Winter Gardening in the Maritime Northwest: Cool-Season Crops for the Year-Round Gardener
(This one is pricey, check with your library or local used book seller. And if anyone knows of a great book, which is still in print, that gives details of how wind breaks and microclimates work for the winter garden let me know.)

Four-Season Harvest: Organic Vegetables from Your Home Garden All Year Long

Be sure to check with your local library—and if they don’t have copies they may be able to request a copy from another library system for you to read.

Don’t forget to do some searches on the Internet—there is lots of information available.

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