Viewing post #72498 by psa

You are viewing a single post made by psa in the thread called Paul's geodesic dome, part 4: Door, Ventilation, and more.
Feb 24, 2010 3:39 AM CST
Name: Paul
Eastern WA
DG: tropicalaria
A few other notes on the greenhouse:

With a single 1500 watt, 120 volt heater I can maintain a 20 degree F differential to outside temperatures throughout the winter. It takes 14000 BTUs to reliably provide the 40 degree differential required by our coldest days most years, including losses due to safety venting. If I were to better insulate the bottom portions of the structure and the north wall, as originally planned, and switch all of my heating to electricity, as still planned (hydroelectric is cheaper than gas here, even for heating) I could certainly realize greater economies of heating. Eventually I plan to run as much as a 65 degree differential, with 30000 BTUs of available heating.

I do maintain ponds, aquariums, and fresh water storage totaling about 250 gallons in the greenhouse, which provides some thermal ballast. I have no idea how much, since they have been present since before I sealed the structure.

I installed low pressure misters on the second tier ring (~7' up) around half the greenhouse. These provided 15-20 degrees of cooling when run 5 minutes at 20 minute intervals during our 115 degree weather, keeping things below 100F. Unfortunately, they clogged after the first year they were installed and I haven't been been able to locate the problem. I will be installing a pump and high pressure misting system this year to take its place.

Most of the floor is currently bare, though I have an ever expanding section of 1-2" river rock starting from the door. I'm conflicted over this, but will probably cover most of the floor with small gravel or rock eventually.

Finally, cost estimates. These are a few years old now, but material costs vary quite about regionally anyway.
Basic Frame - $700
Glazing in and out - $250
Other parts added - $600

Frame costs are mostly dependent on the price of lumber. See Part 1: Design and Preparation for framing materials required.

This quantity of quality glazing always represents a significant cost, and I don't think the amount listed is unusual. Unfortunately, it is only rated for four years and has to be repurchased and installed. I wouldn't skimp on it, though. I highly recommend the woven material I showed in part 3: Plastic covering for its strength, ease of handling, durability, and scattering light transmission. Still, polycarbonate or something I didn't have to replace so often would certainly be nice. I'll be pricing it out this year.

Other parts' cost will be higher or lower depending on choice of door, vents, heating and cooling system, etc. This number probably has little relation to the type of greenhouse constructed, and is probably least informative for someone trying to construct a similar structure.

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Cubit owner: psa