The Walden Effect: Farming, simple living, permaculture, and invention.

Low-cost greenhouse add-on

Solar a steal

Mark and I are focusing in on the idea of a small greenhouse addition on the south side of our trailer to keep our dwarf citrus happy next winter, so I was thrilled when Daddy sent me an envelope of clippings.  Back when I was in diapers, Daddy was working for a non-profit (Scott County Rural Areas Develoment Association, or RADA) that helped low-income residents of southwest Virginia build greenhouse additions to lower heating bills.

Add-on greenhousesAfter some experimentation, RADA came up with a way to build eight-by-eight-foot greenhouse add-ons for $400 (about $994 in today's dollars).  To keep costs low, they used unskilled labor and simple construction techniques:

"The $400 greenhouse is well built and well insulated.  Railroad ties or treated four-by-fours are used for the foundation, which is insulated with two-inch polystyrene at a depth of two feet.  Walls are standard framed, with four to six inches of insulation.  The tin roof is supported by site built trusses which allow for 12 inches of insulation and a well ventilated air space.  Costs are kept down by using sawmill lumber or used lumber for framing, leaving more of the $400 for insulation and glazing.  The glazing consists of an outer layer of kalwall or similar material and an inner layer of six mil UV plastic.  A movable shutter of foam board cut to fit the spaces between the two-by-four uprights is used for night insulation."
--- "Solar a 'steal' in Virginia."  August 1981.  A.T. Times.

As you can tell from the description, Daddy's greenhouses were really sunrooms, with solid roofs and glazed walls.  I've been pondering how to keep our add-on greenhouse from turning the trailer into a solar cooker in the summer, so this idea might make sense.  On the other hand, you would obviously get less winter solar gain using the sunroom concept than if you glazed the roof as well.

Greenhouses provide heat

Another article provided data on how well one of the greenhouses functioned:

"Only on January 11 when the mercury dropped to zero did Pauline [Bishop] turn on a small electric heater to protect her plants.  On this particular occasion, the thermometer inside the greenhouse registered 38 degrees." 
--- "Greenhouses Provide Heat."  June 9, 1982.  Scott County Herald-Virginian.

Read more about sunrooms in this 99 cent ebook!The article went on to say that Pauline reported a decrease in her heating bills due to the greenhouse add-on.  She found it easy to manage how much heat moved from the greenhouse into the kitchen since she could simply open and close a window between the two structures.  (As a side note, most of the greenhouses built during this project used black water barrels as thermal mass, but Pauline installed a brick floor instead so she could use all of the greenhouse space for plants.)

If I were a real reporter, I'd try to track down some of the recipients of RADA's greenhouses to see how long the structures lasted and how the owners ended up feeling about them in the long run.  Since I'm instead a lazy homestead blogger, I'll just followup with some more construction techniques that Daddy's promised me --- stay tuned!

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About us: Anna Hess and Mark Hamilton spent over a decade living self-sufficiently in the mountains of Virginia before moving north to start over from scratch in the foothills of Ohio. They've experimented with permaculture, no-till gardening, trailersteading, home-based microbusinesses and much more, writing about their adventures in both blogs and books.

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Hi Anna,

It would be nice to see the plans :).

I have built a prototype for use in NH (8x12). It would be worthwhile to describe and catalog known working versions along with comments, costs, etc. Also, suggestions for improvements. Also, a stand by itself version.

I searched but did not find any more details of what you describe, except I did get back to this page!

Lots of government grants of various types. Ho Hum.... What else is new!


Comment by john Tue Apr 30 09:39:02 2013

John --- I'd be interested to hear more about your greenhouse --- maybe you'd like to make a guest post about it? Did you keep an eye on temperature inside it? How about keeping track of costs?

Maybe your comment will tempt Daddy to brave the shed to find those plans for me. :-)

Comment by anna Tue Apr 30 12:12:12 2013

I found your page a few months ago after looking through your books on amazon. I have really been appreciating your viewpoint! I am a biologist and it really puts a different spin on how you look at things. I have been working on many of the same projects as you and have appreciated hearing of your experiences, since I am not nearly as far along as you, having only been doing it for 3.5 years. Imagine my surprise when I learned that you also live where I grew up! I am from south-west virginia. Bristol to be exact, and have only been in Mississippi for nearly 4 years. Anyhow, I was reading this post because I have really been considering building a green-house myself, and realized that one of the articles in your post was written by a relative of mine. Just wanted to share and thank you for all of your insight! I'm sure I can't give you nearly as much helpful info, as you are further along than me at this, but feel free to stop by my page!


Comment by Kristin Tue Apr 30 12:46:52 2013

Johm whereabouts in NH are you? We are likely moving there within a year.

Anna- love that hairdo in the last article! We were considering building something like this along our south foundation, but since we are moving, we wont build it here. Would have warmed up the downstairs considerably I'm certain.

Comment by Deb Tue Apr 30 20:03:50 2013

A few of the best ways to combat the heat in summer: 1.Be able to disconnect the greenhouse from your trailer's walls 2.Add plenty of ventilation that can be turned on during summer only. 3.Remove your thermal mass 4.Add removable insulation (foam insulation, several panels thick) panels that will be placed on it during summer... you could also add these between the greenhouse and yours at this time as well. Hope this gives you a few ideas! "Check out my Survivalist Blog at the Clever Survivalist and read daily Survival Guide content."

Comment by Clever Survivalist Blog Tue Apr 30 23:30:08 2013

Hi all,

Deb - I live in Concord, NH. I am writing this from Pembroke, next town over. I have been helping some local farmers and doing soil tests etc.

Anna - I will try to get motivated to write some stuff. I am growing in several places. Two inside and 3 outside. I have one stand alone building along the lines of what you pictured. I have a 2nd stand alone on blocks, but the plastic is long gone on that one right now.

Lots of ideas and trials. Nothing really as a good example. Then again as Henry Ford once said. Experience is the best teacher. And you writings really inspire me and I am sure countless others :).

I continue to experiment and build and try to dust off my notebook to keep notes as I go along!

Lots of fun!


Comment by john Thu May 2 10:23:18 2013

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