PS: Has anyone built their glazed walls with double paned windows?
It's probably only 2 has expensive for about the same or better R value
and it comes already framed. Any ideas there ???????????
I know somebody who built an entire greenhouse out of Anderson
skylights... Of course he works for a building supply company, so I
presume he got a good deal. Too expensive for the rest of us.
I think the main problem with heavily insulating your glazing is that
it inevitably will decrease your light transmission. Which in turn will
decrease the solar gain you get during the day. Triple wall is probably
as good as you are going to get and still be able to grow plants. If
you really really feel the need for insulating your glazed surfaces,
consider covering the glass only at night. You could throw an
insulating blanket over the top, or rig some system to deploy it when
the sun goes down (like a venetian blind).
Since I'm full of wild ideas lately, let me tell you what I really want
to do with a greenhouse some day. Insulate the heck out of the north
wall, and bury the whole structure a few feet. Glaze it normally
(probably triple wall, since I grow lower light species). Hot water
heat. Here is the kicker, collect thermal energy in a big hot water
tank using some solar collectors. You'd still need a boiler of some
sort, but you could pipe your solar hot water to it. You can get really
good evacuated tube collectors for not much money, they will heat water
even when it is cloudy (not as well, of course). My consultants tell me
this is a 'solar flywheel', like the flywheel on your car it stores and
smooths the release of energy.
Anyway, I've talked to a bunch of solar people about my wild and crazy
schemes, and they all agree that the real way to save money is to
insulate the heck out of the greenhouse. Then and only then is it worth
trying to save more money with fancy technology.
And consider your geography. I don't know where you are, but if you
are in Georgia or Texas, it might get cold for a little while, but you
need to consider how much you are going to spend on insulation and how
much you will save in heating bills. Do the math and see if it makes
sense. Now for me, in the great white north, I need every little bit I
can get. I've already spent over $2000 on propane this year, and I'll
need to fill the tank up again in a few weeks.
Rob
--
Rob's Rules:
http://www.msu.edu/~halgren
1) There is always room for one more orchid
2) There is always room for two more orchids
2a) See rule 1
3) When one has insufficient credit to obtain more
orchids, obtain more credit
LittlefrogFarm - Growing the plants Rob likes. )