On Tue, 26 Mar 2013 16:03:49 -0400, Metspitzer
wrote:

The idea of painting roads and rooftops white in order to combat
carbon emissions has been around for years.

The limiting factor here would be carbon emissions. The idea of white
roofs making the house cooler is half a century old or more.

It is surprisingly simple
and effective and yet has not been implemented much.

A study at the Lawrence Berkeley National Laboratory found that cooler
pavement and roofs leads to cooler cities and an overall cooler world.

Since buildings with white roofs reflect far more sun than those with
black roofs, these buildings stay cooler. Less air conditioning has to
be used, lowering the overall energy required to run the building.

Also buildings with black roofs heat the space below them and this
heat is carried spread by the wind. This raises the ambient air
temperature in what is known as the urban heat island effect. Black
roofs also radiate energy back into the atmosphere to be absorbed by
clouds. This heat is then trapped by the greenhouse effect.

As such, white roofs is one of the quickest and most cost-effective
ways to reduce our carbon emissions. In an initiative launched by the
Energy Department, the federal government hopes to exemplify the
benefits by using these light roofs on their buildings.

http://newscenter.lbl.gov/news-relea...ide-emissions/

Thanks.

I didn't want a white roof because I was afraid it would look worse
when it got dirty, so my next door n'bor and I replaced our roofs with
light brown. I can tell the difference. Even when the roof fan is
turned off, it no longer gets so hot on the second floor that I can't
go there. It's always moderately comfortable on the second floor (and
less hot than that on the main floor and cool in the basement) (I
only use AC about 10 days a summer, and last summer not at all because
it was broken.)

OTOH, I used to use the attic heat to heat the house the last part of
fall and first part of spring, and the attic doesn't get hot enough to
do that anymore.

In Indianapolis, I used to drive by the home of one of the richest
guys in town, and the new home of his son. Brown asphalt shingles.
By the end of the firs summer, the brown shingles were off and white
shingles were on. This was about 1962. The benefits of a white roof
have been known for a long time.

And check out your car. Why people buy black cars, with black seats
no less, anywhere but the Yukon, escapes me. It takes more AC to
cool them, and unless you use a remote starter, it's like Hell from
the time you get in the car until the AC has finally cooled it off
some. I have a light tan roof, white seats, and a tan steering
wheel. I can get in the car, sit on the seat with short pants on, and
touch the wheel without suffering on the hottest summer day, whether
the convertible top is up or down.