re: utility costs/ environment gain SOLAR.KnowledgePublications.com

re: utility costs/ environment gain
27 apr 1999
m.f. wrote:

>...i am very decidedly in favour of hydronic floor heating... very
>energy-efficient, suitable for low-temperature heating systems like
>solar thermal, and it also looks good in a drawing ;-)

there's a new one :-) one might also make a warm floor by allowing
some warm air to heat a living space floor above a sunspace or
solar closet in a basement on grade. 

>... a sunspace sounds good too, we will be building the house out in the
>forest in the cevennes (mountain area) in france, and i've been thinking
>about a sunspace but i'm a little worried about the durability of the
>materials. there are a lot of litle forest animals there, ferrets and such,
>and i'm afraid they would destroy plastic film very soon.

there's a 10 cm hole at each end of my big poly film sunspace made by local
critters, a ground hog for one. the creatures don't seem to feel a need to
make more holes, and these holes hardly affect the thermal performance. the
groudhog and my cat and a neighboring cat periodically wander around in the
sunspace, but i don't get more excited about that than if they were walking
around on an uncovered patio. one might exclude them with a layer of wire
mesh outside the lower part of the plastic film. 

>i actually think glass is a better idea, or lexan or some other hard
>transparent plastic, practically unbreakable as there are...

polycarbonate seems nice, in 49" widths on 50' rolls, at about $13/m^2 plus
$10 ups shipping. it can be cut with scissors, but it seems animal-proof.
polyethylene comes in much larger rolls, eg 10 m wide and 40 m long, and
only needs attaching at the perimeter, and costs about 50 cents per square
meter with a 4 year guarantee. it might last 10, if covered with greenhouse
shadecloth in the summer. glass seems very expensive at about $50/m^2, with
a requirement for a more rigid supporting structure and foundation. 

>...there is no alternative to solar, except wood (messy, co2-environment
>unfriendly, and you have to keep chopping)...

ideally, solar heating is only done once, with an inexpensive, reliable,
automatic system.

>and gas in bottles (expensive too, only good as auxiliary). there are no
>electric-lines in our area. if we'd have to pay to get wired to the grid,
>that would be more expensive than anything, i assure you.

a propane or gasoline or diesel generator combined with a few batteries and
an inverter could be a nice electricity and backup heat source. or water-
cooled pvs with simple 2:1 reflectors in the upper part of a sunspace... 

nick