[Greenbuilding] [BULK] Sunspace progress

[Lawrence Lile]

Fun stuff!

>
> My 8 new site-built low-mass sunspace "windows" are 2 4'-wide x 16'-tall
> layers of $1/ft^2 10-mil HP92W polycarbonate film on flat 1x3 frames
> with 3M 4432 3/4"x1/16" double-sided vinyl (omigod!) tape and 1/8"x3/4"
> painted steel cap strips and silicone caulk at the corners.
>

Are you using plain wood or treated wood?  I found plain 2x4's not to last on these kinds of structures. Moisture tends to get into cracks and crevices, it's easy for things to heat up in the day then condense on the structure at night.   The wood might be happier if it was stained or painted.  Can you replace the plastic?  How long will the plastic last in full sun - 3-4 years?  More?

> These windows don't have to be great insulators, since the 32' wide x
> 16' tall x 12' deep lean-to sunspace and solar attic above with a
> 32'x20' steep Dynaglas roof get cold at night. The low-mass floor will
> be green Astroturf (anyone have a better suggestion?) over modified
> stone over geotextile fabric over polyethylene film on the ground.

You could lay down a layer of foam, cover it with a little sand, then cover that with pavers.  Not totally low mass, but low enough and looks better than plastic grass.  You can also just use carpet - I used to use recycled dumpster-dived carpets for garden paths and so forth.  They don't last forever in contact with soil, but the price is good.

>
I'm
> thinking of adding an 8'x32' people net 8' above the floor.
>

What's a people net?  Does that prevent the zoo animals from escaping? Or perhaps it is a data network made only of people? <Grin>


> Each glazing panel has 2 1/8" ID polyethylene tubes at the bottom. They
> are inflated in series with DOT push tubing couplers (truck parts) to
> 0.15" of water with dry air from a $10 12V tire compressor (PV-powered,
> of course :-) in a boxful of Tyvek clay desiccant bags, with a
> Magnehelic 0-0.25" pressure gauge and a Dwyer 1710-0 pressure switch,
> for less wrinkling and wind fatigue.
>

Wow - good luck with that.  If I understand this correctly, the wood itself will be part of the envelope holding the air pressure.  Hmmm - porous stuff.

Getting dry air inside is a good idea, your dessicant bags won't last forever, eventually they don't dry anymore unless baked.  If your pump needs to re-fill periodically (I predict it will) then you'll eventually be pumping moisture into the glazing panel.

> We are chasing a small air leak now, altho we tested the panels with a
> soap bubble solution before installing them. With the pressure switch on
> a T on the first panel output, the compressor on-time is about 5
> minutes. I just added a manual reset latching relay with an LED to
> indicate when the compressor runs. If it never runs again, we plan to
> fill the panels with argon.
>

That's expecting a lot out of a homemade panel, but if you really were careful about sealing it up, it might work.  Give us an update in a few weeks.

Any reason you didn't go with commercial greenhouse panels (dynaglas etc) for the whole thing?  (besides of course, just to show that it can be done!)

--Lawrence