Painting roofs white can actually help lower the temperature of a city

[Metspitzer]

The idea of painting roads and rooftops white in order to combat
carbon emissions has been around for years. 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-releases/2010/07/19/cool-roofs-offset-carbon-dioxide-emissions/

 

[trader4]

The idea of painting roads and rooftops white in order to combat
carbon emissions has been around for years. 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-releases/2010/07/19/cool-roofs-offset-...

I say it's total BS. The best study I saw on roof color was
done in FL. They took a bunch of identical houses, put varying types
and color of roofs on them, fully instrumented
the houses, and measured during AC season.

The conclusion was that if you had a shingle roof, it made
about a 10% difference in energy usage if you had a black
rood or a white roof. And that was the energy usage with
the houses unoccupied. They did another test when they
were occupied and the energy usage difference dropped to
just a few percent. Which makes sense, because when
occupied the energy usage is going to be higher, because
people are opening door, turning on TVs, cooking, etc.

It would also seem to me that it's junk science to suggest
that lighter roofs lead to a cooler world. X amount of solar
radiation is hitting the earth. Almost all of it is going to go
into heating it.
So, it's hard to believe that because something is white
that radiation is going back from earth to outer space.

 

[Bob F]

I say it's total BS. The best study I saw on roof color was
done in FL. They took a bunch of identical houses, put varying types
and color of roofs on them, fully instrumented
the houses, and measured during AC season.

The conclusion was that if you had a shingle roof, it made
about a 10% difference in energy usage if you had a black
rood or a white roof. And that was the energy usage with
the houses unoccupied. They did another test when they
were occupied and the energy usage difference dropped to
just a few percent. Which makes sense, because when
occupied the energy usage is going to be higher, because
people are opening door, turning on TVs, cooking, etc.

It would also seem to me that it's junk science to suggest
that lighter roofs lead to a cooler world. X amount of solar
radiation is hitting the earth. Almost all of it is going to go
into heating it.
So, it's hard to believe that because something is white
that radiation is going back from earth to outer space.

Nevertheless, it happens. That's one of the issues with global warming. As the
glaciers and polar ice caps melt off, the land/sea under them will absorb heat
currently radiated back into space by the white ice/snow, warming the planet
even more. Roofs could make a similar difference, and that difference would not
be fully expained by air conditioning costs.

Imagine covering roofs with mirrors. Do you think they would radiate energy into
space? If you don't, would you expect someone in space would see the glare if
the reflection were aimed at them? What they see is energy reflected into space.
White paint reflects almost as much energy as a mirror, but not directionally
like a mirror, so less of the reflection might make it to space than a mirror's
reflection.

White paint for the roads - not the slippery kind they use for road markings.
That would be stupid and cause accidents.

 

[Mitt Romley]

I say it's total BS. The best study I saw on roof color was
done in FL. They took a bunch of identical houses, put varying types
and color of roofs on them, fully instrumented
the houses, and measured during AC season.

Here's an aerial view of Disney's Epcot Center. Notice the white roofs.
Disney knows what the **** they are doing!

http://binged.it/YdDggm

 

[micky]

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-releases/2010/07/19/cool-roofs-offset-carbon-dioxide-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.

 

[(PeteCresswell)]

Per (e-mail address removed):

I say it's total BS.

I used to hang out at a beach near the yacht harbor next to the Ilikai
hotel in Waikiki.

For years and years, the parking lot was just plain old dirt - light
brown, somewhat dusty.

Then somebody got the bright idea of paving the parking lot with
blacktop.

It made a huge difference. The parking lot area and adjacent beach went
from being comfortable to being almost unbearably hot without a strong
breeze to mitigate it.

So, unencumbered by any other knowledge, my money's on the white
roofs...

 

[gregz]

The idea of painting roads and rooftops white in order to combat
carbon emissions has been around for years. 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-releases/2010/07/19/cool-roofs-offset-carbon-dioxide-emissions/

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.

Greg

 

[gregz]

I say it's total BS. The best study I saw on roof color was
done in FL. They took a bunch of identical houses, put varying types
and color of roofs on them, fully instrumented
the houses, and measured during AC season.

The conclusion was that if you had a shingle roof, it made
about a 10% difference in energy usage if you had a black
rood or a white roof. And that was the energy usage with
the houses unoccupied. They did another test when they
were occupied and the energy usage difference dropped to
just a few percent. Which makes sense, because when
occupied the energy usage is going to be higher, because
people are opening door, turning on TVs, cooking, etc.

It would also seem to me that it's junk science to suggest
that lighter roofs lead to a cooler world. X amount of solar
radiation is hitting the earth. Almost all of it is going to go
into heating it.
So, it's hard to believe that because something is white
that radiation is going back from earth to outer space.

Color isn't everything. Use reflectivity index. Higher energy cost is also
meaning more energy creation, more heat. The insulation under the roof is
going to be the main factor.

Greg

 

[gregz]

Per (e-mail address removed):

I used to hang out at a beach near the yacht harbor next to the Ilikai
hotel in Waikiki.

For years and years, the parking lot was just plain old dirt - light
brown, somewhat dusty.

Then somebody got the bright idea of paving the parking lot with
blacktop.

It made a huge difference. The parking lot area and adjacent beach went
from being comfortable to being almost unbearably hot without a strong
breeze to mitigate it.

So, unencumbered by any other knowledge, my money's on the white
roofs...

There is also a big difference in artificial grass vs natural.

Driving around the city suburbs, it's often a relief to drive through a
heavy tree area. Seems 15-20 degrees cooler.

Greg

 

[larrymoencurly]

I say it's total BS. The best study I saw on roof color was
done in FL. They took a bunch of identical houses, put varying
types and color of roofs on them, fully instrumented the houses,
and measured during AC season.

The conclusion was that if you had a shingle roof, it made
about a 10% difference in energy usage if you had a black
rood or a white roof. And that was the energy usage with
the houses unoccupied. They did another test when they
were occupied and the energy usage difference dropped to
just a few percent. Which makes sense, because when
occupied the energy usage is going to be higher, because
people are opening door, turning on TVs, cooking, etc.

Was that based on stock white shingles or shingles painted white?
Because surfaces painted white reflect roughly 90% of the sunlight,
while regular white shingles reflect only 10%.

 

[Oren]

Was that based on stock white shingles or shingles painted white?
Because surfaces painted white reflect roughly 90% of the sunlight,
while regular white shingles reflect only 10%.

Years ago, a flat roof in Florida had a white quartz on them. In the
desert here, I have seen a couple that used white rocks. Strange,
considering the weight of the rock of the roof and the home age.

Sample photo:

<http://www.navarroroofing.com/images/rock-roof-redondo-beach.jpg>

 

[makolber]

trees are the answer
the co2 level actally drops during summer in the northern hemisphere due to all the trees
they absorb co2 and store it in the wood
mark

 

[Oren]

trees are the answer
the co2 level actally drops during summer in the northern hemisphere due to all the trees
they absorb co2 and store it in the wood
mark

"Fossils of a species of extinct giant camel have been discovered in
the Canadian High Arctic by researchers from the Canadian Museum of
Nature."

Photo of giant camels and trees (rendition).

Read more at
<http://planetsave.com/2013/03/07/ex...vered-in-the-high-arctic/#T3CE6p2wethuo4Tx.99>

Must be that global warming thing.

 

[harry]

I say it's total BS.  The best study I saw on roof color was
done in FL.  They took a bunch of identical houses, put varying types
and color of roofs on them, fully instrumented
the houses, and measured during AC season.

The conclusion was that if you had a shingle roof, it made
about a 10% difference in energy usage if you had a black
rood or a white roof.   And that was the energy usage with
the houses unoccupied.  They did another test when they
were occupied and the energy usage difference dropped to
just a few percent.  Which makes sense, because when
occupied the energy usage is going to be higher, because
people are opening door, turning on TVs, cooking, etc.

It would also seem to me that it's junk science to suggest
that lighter roofs lead to a cooler world.  X amount of solar
radiation is hitting the earth.  Almost all of it is going to go
into heating it.
So, it's hard to believe that because something is white
that radiation is going back from earth to outer space.

The last bit about reflecting heat back into space is true.
But because roofs are so small the effect is insignificant.
http://en.wikipedia.org/wiki/Albedo#Examples_of_terrestrial_albedo_effects
http://en.wikipedia.org/wiki/Asian_brown_cloud#Global_warming_and_dimming

 

[harry]

I say it's total BS.  The best study I saw on roof color was
done in FL.  They took a bunch of identical houses, put varying types
and color of roofs on them, fully instrumented
the houses, and measured during AC season.

The conclusion was that if you had a shingle roof, it made
about a 10% difference in energy usage if you had a black
rood or a white roof.   And that was the energy usage with
the houses unoccupied.  They did another test when they
were occupied and the energy usage difference dropped to
just a few percent.  Which makes sense, because when
occupied the energy usage is going to be higher, because
people are opening door, turning on TVs, cooking, etc.

It would also seem to me that it's junk science to suggest
that lighter roofs lead to a cooler world.  X amount of solar
radiation is hitting the earth.  Almost all of it is going to go
into heating it.
So, it's hard to believe that because something is white
that radiation is going back from earth to outer space.

You can easily tell the difference with white cars and black ones in
the sun.

 

[dadiOH]

Per (e-mail address removed):

I used to hang out at a beach near the yacht harbor next to the Ilikai
hotel in Waikiki.

For years and years, the parking lot was just plain old dirt - light
brown, somewhat dusty.

Then somebody got the bright idea of paving the parking lot with
blacktop.

It made a huge difference. The parking lot area and adjacent beach
went from being comfortable to being almost unbearably hot without a
strong breeze to mitigate it.

There used to be a nice breeze. Until they built the Ilikai which blocked
the trades. Ala wai Harbor was much more comfortable before the Ilikai.
For that matter, all of Honolulu was much more pleasant pre-high rise.


--

dadiOH
____________________________

Winters getting colder? Tired of the rat race?
Taxes out of hand? Maybe just ready for a change?
Check it out... http://www.floridaloghouse.net

 

[trader4]

Nevertheless, it happens. That's one of the issues with global warming. As the
glaciers and polar ice caps melt off, the land/sea under them will absorbheat
currently radiated back into space by the white ice/snow, warming the planet
even more. Roofs could make a similar difference, and that difference would not
be fully expained by air conditioning costs.

Imagine covering roofs with mirrors. Do you think they would radiate energy into
space? If you don't, would you expect someone in space would see the glare if
the reflection were aimed at them? What they see is energy reflected intospace.
White paint reflects almost as much energy as a mirror, but not directionally
like a mirror, so less of the reflection might make it to space than a mirror's
reflection.

White paint for the roads - not the slippery kind they use for road markings.
That would be stupid and cause accidents.- Hide quoted text -

- Show quoted text -

Then explain why when the experiment was actually done in FL,
using white shingles vs black, it only made a few percentage
points difference in AC energy usage for occupied homes.
And then factor in that the percentage of the earth's surface
that is covered by roofs is negligible compared to the total
surface.

 

[willshak]

The idea of painting roads and rooftops white in order to combat
carbon emissions has been around for years. 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-releases/2010/07/19/cool-roofs-offset-carbon-dioxide-emissions/

Igloos are built with white roofs and they remain very cool inside.

 

[George]

I say it's total BS. The best study I saw on roof color was
done in FL. They took a bunch of identical houses, put varying types
and color of roofs on them, fully instrumented
the houses, and measured during AC season.

The conclusion was that if you had a shingle roof, it made
about a 10% difference in energy usage if you had a black
rood or a white roof. And that was the energy usage with
the houses unoccupied. They did another test when they
were occupied and the energy usage difference dropped to
just a few percent. Which makes sense, because when
occupied the energy usage is going to be higher, because
people are opening door, turning on TVs, cooking, etc.

It would also seem to me that it's junk science to suggest
that lighter roofs lead to a cooler world. X amount of solar
radiation is hitting the earth. Almost all of it is going to go
into heating it.
So, it's hard to believe that because something is white
that radiation is going back from earth to outer space.

Maybe thats what Limbagh told you but reradiation into space is an
actual physical phenomena.

http://earthobservatory.nasa.gov/Features/EnergyBalance/page6.php

 

[Doug]

I say it's total BS. The best study I saw on roof color was
done in FL. They took a bunch of identical houses, put varying types
and color of roofs on them, fully instrumented
the houses, and measured during AC season.

The conclusion was that if you had a shingle roof, it made
about a 10% difference in energy usage if you had a black
rood or a white roof. And that was the energy usage with
the houses unoccupied. They did another test when they
were occupied and the energy usage difference dropped to
just a few percent. Which makes sense, because when
occupied the energy usage is going to be higher, because
people are opening door, turning on TVs, cooking, etc.

It would also seem to me that it's junk science to suggest
that lighter roofs lead to a cooler world. X amount of solar
radiation is hitting the earth. Almost all of it is going to go
into heating it.
So, it's hard to believe that because something is white
that radiation is going back from earth to outer space.

I've seen many model homes around Houston boasting energy saving
features and they don't have white roofs so I think that proves you
right. Our typical summer days are 95F but two or so years ago, we
often had 102F summer days.