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Green house, house.. How much cheaper and more energy efficient can you build without loads?

mikeolder | Posted in General Questions on

I remember reading and dreaming about a home that was built inside of a glass greenhouse. The home inside was a conventional house, but what if your main design goals were energy efficiency, and low building cost for the rest of us?

What recyclable low-cost material could you build a home with that is more energy efficient than the methods used today because all external loads had been transmitted to the greenhouse, requiring less structural high thermally conductive materials in the envelope you want to condition

 Just throwing this out there…

 For example, a cardboard house or pods assembled with mastic (lol, yes alittle grassroots) and insulated with cellulose inside of a unconditioned greenhouse with conventional insulated roof. You wouldn’t need to have 100% glass coverage, and the windows in your cardboard house would not have to open and close. Or maybe aircrete, insulated tent, bamboo? 

 I imagine the cost of a big high quality greenhouse combined with a house built of any materials to be equal or more $ than a conventional stick built. But maybe the greenhouse could withstand  200 years? Meaning, the property had changed hands multiple times, the greenhouse remains, but the house inside got replaced/remodeled/updated by each new owner for a reasonable price with recyclable materials? Isn’t that more realistic than expecting passive house owners to be happy after many deep mechanical retrofits?



  1. Expert Member
  2. Expert Member
    DCcontrarian | | #2

    I've seen what I think is a similar idea in high-rise construction where the apartment units are modular, they can be slid in and out. You separate the building envelope from the finished interior.

    But to answer your question, "how much cheaper and more energy efficient can you build?" I'd say the answer is zero. Read up on Pretty Good Houses. What you're proposing sounds more expensive than a PGH.

  3. mikeolder | | #3

    Thanks. This one is neat too.. But you have to admit, overbuilt on the inside, especially if it were built single level.

    This is what happens when you have a rotator cuff surgery. Ive got tons of time on my, hand.. Get it? I wonder if this is what cabin fever feels like?

  4. Expert Member


    I like the idea of a more permanent shell within which the interior can be easily adapted as conditions change over time, but if we sat down to decide what that outer skin would look like, I doubt it would be a greenhouse.

    They are fragile and create conditions (heat, humidity) that need moderating, but still require a complete separate skin between their interior and the house inside them.

    Double envelope houses were quite popular among progressive builders in the '80s, but the extra effort involved never seemed to yield enough benefits to justify the extra effort involved.

    My preferred shell would be closer to the masonry townhouses you see in many older cities but with a load-bearing structure such that interior changes are easily done.

    1. Expert Member
      DCcontrarian | | #5

      DC probably has 50,000 of those townhouses, they're not great to renovate.

      I see two issues. First, buildings tend to get torn down not because the envelope is failing, but because they are functionally obsolete. Second, when you look at all of the costs of a finished building, the cost of the shell is relatively minimal -- which is why buildings tend to get torn down.

      Building a more elaborate shell just means more to go to the landfill when the design has outlived its usefulness.

  5. Trevor_Lambert | | #6

    I think you've got some false premises built into this idea. For one, I don't think having the house inside a glass greenhouse helps much in terms of structural loads. As for conditioning, it would help in the winter, but hurt in the summer. This might only begin to be practical in the far north. The fact the example house is in Sweden is no coincidence.

  6. walta100 | | #7

    Seems like something I read in a 1960s Popular Science magazine.

    The shell is 100% windows. Windows make terrible wall due to the very low R value and very high cost.

    To my ear this is a failed passive solar daydream carried to its extreme limit.

    Total energy saved would be a negative number compared with a PGH home and likely to cost 5 times as much to construct per square foot of interior space.


    1. mikeolder | | #8

      I'm not the only one who thinks a home inside a green house would be neat.

      1. Expert Member
        MALCOLM TAYLOR | | #9


        Attaching or integrating a greenhouse for growing plants into the design may make sense, on single family or multi-family projects

        That's very different than enclosing a house in a glass shell, or trying to incorporate living spaces into a greenhouse, as your link shows. Fully glazed sunrooms are a close cousin of that approach. They appeal in the abstract - happy families eating or enjoying the view in a glass addition - but the reality is these spaces are largely unusable. Where I am there are two companies whose business is dedicated almost entirely to removing problematic sunrooms, either because they are impossible to condition properly, or that they soon leak.

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