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veggievicki

a sphere (dome) is the most efficient

veggievicki
11 years ago

Geometrically speaking, a half sphere (dome) gives the least wall exposure for the amount of interior space. Is it just not practical to build a dome? Is the way materials are sold the main reason it's not used more? I think high tunnels are absolutely the most cost effective for non heated space, but I was wondering if I were to construct one heated greenhouse on my place, would a dome be a good option.

Comments (7)

  • squirrellypete
    11 years ago

    I would think with a dome it also presents a challenge regarding shelving. I know many people incorporate the vertical walls into their shelving/beds/etc....Speaking of a greenhouse here of course and not a hoop house.

    Not saying a dome isn't more efficient with heat or that there aren't ways around the shelving issue, but it would require a little thinking outside the box (no pun intended lol).

  • steve_in_los_osos
    11 years ago

    Indeed, with a dome you lose some plantable area unless you have more than a half-sphere (or a half-sphere with a cylindrical side wall). The slope at the edges makes for very little head room until you move closer to the center.

    With a high tunnel you have some control over this problem with the slope of the walls (i.e., is it really a "high" tunnel, a "medium" tunnel or a "low" tunnel). With a rectangular structure, you can have better use of the space near the walls.

  • cole_robbie
    11 years ago

    Cubic interior space versus surface area of exterior walls is not that useful of a measurement unless you're growing vertically, with tall plants or hydroponics. If you are heating a greenhouse, you can insulate your north wall, which more than makes up for the greater surface area of typical northern greenhouse designs.

  • trianglejohn
    11 years ago

    Everyone that I know with a home made dome structure suffers leaks - too many joints/edges. But you do often see domes on large botanic garden's conservatories.

  • steve333_gw
    11 years ago

    I'd agree with the previous posters.

    Theory may give the volume/surface edge to dome/circular structures. However practical and other issues override that.

    In a heated structure, allowing for an insulated N wall more than makes up for any advantage the surface to volume ratio a sphere structure may have. Also, there are advantages to orienting a long axis in an e-w direction, for capturing more sun. And there are considerations of minimizing walkways which a narrower footprint can help with.

    But probably the biggest advantage of "rectangular" designs is that all GH building materials come in straight/rectangular dimensions. Building a structure with compound curves (like a dome or sphere) does not fit well with commonly available materials, leading to more waste and expense, and more seams to seal.

  • barrie2m_(6a, central PA)
    11 years ago

    This has been an interesting thread to read. It brings to mind a few historic round barns in our area of central PA. I marveled at the re-shingling project on one round barn still standing that seemed to take a group of professionals the greater part of a summer to accomplish. For these barns the theory was that the animals could all be facing inward to a center feeding area and the manure would be conveniently at the perimeter.

    I can envision a huge multiprism like the Disney Epcot Center attraction- if you had a similar nursury sales area it could be a huge tourist attraction. But in practical growers terms I totally agree with the previous posts.