The Real Bev wrote:

Jeff Thies wrote:
Where are you reading from???

misc.consumers.frugal-living.

Me too. Not many of us left. I think I'm going to bail...

We might discuss the economic and technical aspects, vs "You must be crazy
to think that will work," "Your computer can't even make Pi," "Your attic
can't work, because you haven't installed enough heat pumps," and so on.

Dynaglas polycarbonate costs $1/ft^2. Installing a 4'x12' panel takes 10
minutes. It lasts 20 years but might go longer with a sloped reflective
overhang for less summer sun and more winter sun. Shingles cost about
$0.30/ft^2, plus $0.10 for felt plus $0.50 for OSB? So materials are
a wash, but there's a large labor savings. How much? The solar heat is
worth about $1/ft^2 per year.

How much heat will a dark absorber lose to cold glazing by radiation?
How can we make a dark mesh that will work with a 1-10 meter per hour
face velocity? Black aluminum window screen costs about 25 cents/ft^2
in 4' rolls, but its pneumatic resistance is likely too low. Typar is
cheap, about 10 cent/ft^2 IIRC, but its pneumatic resistance is high.
How about poking some holes in Typar? How many? How big?
Would a geotextile material work better?

http://www.reemay.com Typar comes in wide rolls, eg 9'x111.1'. It's porous,
0.0032L/s-m^2 at 75 Pa, ie 0.00063 cfm/ft^2 at 0.3" H20, eg 0.2 cfm for
an 8'x40' wall, and charcoal on one side. It lasted 5 years on a south wall
of my house, exposed to the weather, but it has a lifetime guarantee :-)

Nick