"mm" wrote in message
...
On Tue, 13 Jul 2010 22:51:39 -0400, LSMFT
wrote:

There is a push to cool the earth, save energy and keep your
home cooler
at less cost to have white roofs. Especially in the cities to
reduce
heat islands.
What about northern states where we heat more than air
condition. Should
we go to white roofs or black roofs or middle colors?

In Indianapolis for many years, there were two big department
stores
downtown. Blocks and Ayres. The Blocks lived just doown the
street
from us, on the nice part of the street, the really nice part,
but we
drove by their enormous house to get home. Later, the son built
a big
house next door, with dark shingles. Four months later, the
shingles
were replaced with white or almost white. This was probably
1961.

My townhouse had dark brown shingles and when my next door
neighbor
and I needed a new roof, I talked him into light brown. White
wouldn't have looked good. He uses his AC a lot and I rarely
use
mine, and I think maybe I helped him more than me, becaues with
the
cooler attic he saves money on his AC and I don't use mine
enough to
save more than a bit of money. For me, in the summer, I'm
pretty
sure the house is not as hot as it was. (Maybe I need more
insulation
on part of the attic floor but most has plenty.)

But in the mid fall and early spring, I turned off the roof fan
so the
attic got as hot as possible and I used the heat of the attic to
warm
the house. That doesn't seem to work anymore. It was only
good for
2 to 4 degrees but it was also the difference between closing
the
windows and turning on the heat, versus leaving them open and
heating
a little bit the house from attic.

All these effects would be a little greater with white. I was
afraid, warned even, that white would look dirty eventually,
although
I don't know why he claimed that. I meant to look at other white
roofs
to see if any looked dirty, but I forgot that until just now,
and I
never did it.

I think I'd still get light colored shingles rather than dark,
no
matter what my habits aare.

Besides the color of a roof, here are a couple more thoughts. In
the desert SW, we have a lot of homes with barrel tile roofs.
Essentially, the house has a waterproof roofing material over the
roof sheathing, and this is then covered with the barrel tile
(made of concrete nowadays) to protect the membrane from UV. A
side effect of this is that the barrel tile, with its "S"-shaped
design creates shade for the roofing material below, together with
terrific convection air flow up under the tile. This reduces
attic temperatures.

In our own home, besides the barrel tile roof, we also have flat
solar panels to heat our pool. Again, they shade the barrel tile,
which in turn shades the roofing membrane. However, there's a
hidden value in that, say, the pool's water is 85f going into the
panels and 88f departing, you essentially have a cold blanket
(relative to the air temperature and sun load here in the desert,
usually) on your roof. There is air circulation under this "cold"
blanket, due to the upper surface of the barrel tile, as well as
below.

Nonny


--
On most days,
it's just not worth
the effort of chewing
through the restraints..