On Wed, 27 Mar 2013 08:10:21 -0700 (PDT), email@example.com wrote:
When I use to travel to Austin, Texas a couple years ago, going north
on I-71, there was a place that I think is some kinda outside lab site
for a local college which has solar panels and a small structure with
grass growing on the roof. I never stopped there but thought it was
interesting what they are trying to do. Do you have to eventually mow
the roof <grin> ?
On 3/26/2013 3:13 PM, firstname.lastname@example.org wrote:
Your recollection of the study's findings is not completely correct.
You're right that in its initial testing of unoccupied homes, it found
an approximate 10% energy savings using a white roof. But it also
found that while occupying the homes increased energy usage overall,
there was no change to the amount saved by the lighter roofs:
"Additional monitoring took place over a month long period with the
homes occupied, but the thermostat set points were kept exactly the
same as in the unoccupied monitoring period. Although average cooling
energy use rose by 36%, analysis indicated no decrease to savings or
demand reduction from the highly reflective roofing systems. The added
heat gains from appliances and people increase cooling system
run-time, with longer periods for the duct system to exchange heat to
the often hot attic space."
And the study's conclusion:
"In summary, this evaluation strongly confirms the energy-saving
benefits of using more reflective roofing systems in Florida.
Selection of colors with higher solar reflectance will result in
tangible cooling energy savings for customers. This is particularly
true for roofing materials such as tile and metal which are currently
available with solar reflectances of 65%-75%. The selection of
reflective roofing systems represents one of the most significant
energy-saving options available to homeowners and builders. Such
systems also strongly reduce the cooling demand during utility
coincident peak periods and may be among the most effective methods
for controlling demand."
The limiting factor here would be carbon emissions. The idea of white
roofs making the house cooler is half a century old or more.
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.
When I was a kid, my dad being a carpenter put a white roof on our
house (Long Island). I think it was either the only one or one of two
in the large neighborhood. It wasn't too white as I recall (I was a
youngster more interested in playing than construction then) so I
don't think it showed the dirt that much but we moved away before it
got to be near the end of its life so I can't say what it looked like
I think they should paint the roads white, plant more trees and grass.
I was amazed with my only light plane flight over the desert. You could
feel everything, roads, tracks, etc. Bump bump.
Someone should try black roof igloo. I propose a government study. about
$5.5 million for start, and cost over runs and all. End up being about 20
million by the end of the year.
Christopher A. Young
Learn more about Jesus
Igloos are built with white roofs and they remain very cool inside.
It's easy to compute what's hot and what's not, and how much can be gained.
Just take a look at the Landsat images from space. They started taking
image scans of the earth in the mid 70's, with the multi spectrum image
scanner. IR temperature of the ground is easy to detect. I think it
actually used a rotating mirror to scan as the satellite moved over a
hundred miles high looking at earth. Was first called ERTS satellite.
environmental resource and technology satellite.
Could very well be true, but your HOUSE will look like shit!
Soot and other particulates will stand out on a white roof. Look around your
neighborhood - do you see any white or light-colored roofs? Well, why not?
And for those you DO find that are somewhat less than dark, don't they look
Heck, you don't have to look at the roof; look at your very own brick work.
Do you think that black mess GREW there? You know, the stuff you have to
power-wash off every few years.
A white roof may very well be useful atop a 27-story office building but for
a one or two-story residence, forget it.
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