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Re: [pfaf] re: tomatoes in greenhouses

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  • Matthew Sleigh
    Crystal fusion heat, solar ponds etc. Some low tech, low energy ways of keeping greenhouses/plants from freezing, there are probably better examples of similar
    Message 1 of 6 , Mar 4, 2011
    • Jonathan Teller-Elsberg
      Another source of information is Darrel Frey s recent book, based on his many years of experience and experimentation in Pennsylvania, The Bioshelter Market
      Message 2 of 6 , Mar 4, 2011
        Another source of information is Darrel Frey's recent book, based on his many years of experience and experimentation in Pennsylvania, "The Bioshelter Market Garden." He's established a working permaculture commercial (small-scale) farm, and one of his key components is a passively heated greenhouse system utilizing both passive solar orientation/design, and incorporation of the waste heat from composting and chickens (maybe other animals as well) to keep the greenhouse warm enough to produce crops through  the winter. http://www.newsociety.com/bookid/4082

        And then, of course, there are the books from Eliot Coleman about his four-season harvesting in Maine (USDA zone 5). He's done quite well with unheated greenhouse and, in his most recent book, details his more recent use of "minimally heated" greenhouse -- that is, greenhouse that are heated only enough to prevent the temperature from falling below something like 34'F / 1.1'C. (His unheated greenhouses will get as low as the teens'F in the coldest weather, but he grows crops capable of withstanding those temps unharmed.) http://www.chelseagreen.com/bookstore/item/the_winter_harvest_handbook:paperback and the older but still relevant  http://www.chelseagreen.com/bookstore/item/fourseason_harvest/

        Other books and online resources also give info on this sort of thing.

        Jonathan

        >>>>>
        Hi there,

        Poultry and other living beings we share our farm/homestead spaces with may
        contribute heat to a greenhouse in winter.

        Peace and love.

        Steve.

        --
        "We have changed the world, and we wonder why things won't stay the same." -Les Lanyon
      • john willis
        No problem - your reply is great and gives much food for thought.John. To: pfaf@yahoogroups.com From: jelsberg@gmail.com Date: Thu, 3 Mar 2011 10:00:40 -0500
        Message 3 of 6 , Mar 4, 2011
          No problem - your reply is great and gives much food for thought.
          John.


          To: pfaf@yahoogroups.com
          From: jelsberg@...
          Date: Thu, 3 Mar 2011 10:00:40 -0500
          Subject: [pfaf] re: tomatoes in greenhouses

           
          Traveler in Thyme,

          Yes, you are right that the benefits of overwintering tomatoes in a heated greenhouse are far outweighed by the problems of unnecessary use of energy. But that assumes that the greenhouse exists only for the tomatoes. If a person has determined that they want/need a (heated) greenhouse for whatever reasons already, then putting some tomatoes into it doesn't much change the energy balance. Still, the joy of a fresh tomato shouldn't overwhelm someone's rational thinking and lead them to install an energy demanding greenhouse just for that simple pleasure.

          John Willis,

          Having sort of defended greenhouses above, now I'll beg to differ with you about the efficacy of solar systems to power heated greenhouses. A passive solar greenhouse is great, of course, though it does entail the embodied energy of the materials that construct it--sometimes really significant amounts of energy. That goes both for greenhouses glazed in glass or in polycarbonate. Polycarbonate is massively energy intensive to manufacture, as, of course, is glass. So all greenhouses, even passive solar ones, should be considered carefully before being installed to determine if they really will be utilized intensively enough to make up for their energy "cost" (not to mention their financial cost).

          PV panels only up the situation. The embodied energy in PV panels is significant and I suspect that, on balance, I'd be better off in terms of global warming gas emissions eating lettuce trucked from California to Vermont all winter than to install PV panels for the purpose of powering a greenhouse for my winter veggies. (As above, if the PV panels are being used for other reasons already, and have the spare capacity to boost a greenhouse's viability, then go for it. But PV expressly for powering a greenhouse? I fear that's a dead weight loss for the planet when all is said and done.)

          I hope I haven't sounded too didactic. Sometimes I get on a high horse when I don't mean too.

          Best,
          Jonathan

          --
          "We have changed the world, and we wonder why things won't stay the same." -Les Lanyon

        • Steve
          Jonathan, No real need to apologise for advising someone to do a thorough accounting of energy. Peace. ... Frank, My friend has geothermal heating already
          Message 4 of 6 , Mar 4, 2011
            Jonathan,
             
            No real need to apologise for advising someone to do a thorough accounting of energy.  Peace.
             
            ----------------------------
             
            Frank,
             
            My friend has geothermal heating already installed under his barn in Ontario, Canada.  Not the Arctic circle, I'll admit, but pretty chilly in winter.  Second-hand information this may be, but he's an ex-economist, and if he would invest his energy in it he's probably done the research. 
             
            I'm sure you'll still do your own research, but perhaps this is a little incentive.
             
            Also, Sepp Holzer of Austria has been doing cold-climate permaculture for decades, and uses the heat retaining capacity of rock in his design to provide warmth.  The sun shines on the rocks and they warm up, then they release the heat after the air cools in the evening.. this effectively extends the day's warmth and prevents frost in microclimates.
             
            Peace,
             
            Steve.
             


            --
            "All that is gold does not glitter,
            Not all those who wander are lost;
            The old that is strong does not wither,
            Deep roots are not reached by the frost.
            From the ashes a fire shall be woken,
            A light from the shadows shall spring;
            Renewed shall be blade that was broken,
            The crownless again shall be king."
            ~  J.R.R. Tolkien

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