Tremendous glare.

This has been discussed in previous threads. The synopsis seemed to be that insulation or an extremely well designed system of air movement was of more value than color; although there are firmly held opinions that the lighter the color, the more heat would be reflected rather than absorbed.

My understanding is that at the end of a sunny day, the accumulative heat absorbed varies little between pale or white shingles and those of darker hues. Once the base substance underneath the gravel is hot, it's hot. Yes, the heat might be slower to reach the asphalt/tar/whatever beneath the gravel if the gravel is white, but that's of little difference after 10 or 14 hours of blazing sun. What matters is how effective measures are in either preventing the heat from reaching the attic (super insulation) or moving that heat out of the attic.

Another point to remember is that white roofs don't stay white. Most studies indicate that reflectiveness decreases by 25% to 50% within 3 years (within a year in areas of high air pollution).

My personal opinion is that I wouldn't pay more just to have a white roof, although I do believe that in temperate climes there is some value to having a pale roof rather than a dark one. I *would* pay lots more to have the equivalent of at least R40 insulation.

How does it look with your style of house? One ranch style house in our neighborhood recently went with a white roof when they re-roofed and it looks horrible. Maybe on a more modern style house it would look better?

swampwiz,
You sound like my hubby :) he wanted a white roof. I would not want to live in a white roof house!

In Florida I had very light gray shingles. My neighbors had medium/dark brown. I don't know if they didn't have good attic insulation or good airflow within the house, but my house was cooler than theirs- it was an obvious difference. The next house will have white/almost white- something that looks good.
Now, I have dark wood roofing- I am in a colder climate and would LOVE for it to help attract warmth in the winter... but I don't think it does- or if t does, it is just too cold here for me to notice.

NY Times just had an interesting article about how well white roofs work. The gist was that white is a far better choice than any other color, worldwide, due to its ability to reflect heat.

Go back and read meldy nva's previous post it is spot on.

This is more global warming propoganda from the Obama administraition, specifically Steven Chu, Secretary of Energy.

The reflectivity is greatly diminished over time and the base materials absorb more heat than is reflected by the color of the shingle.

Insulation, and sealed building envelope construction is far more effective than any light colored shingle.

How much will our health care costs go up with all of these people climbing up on their roofs to scrub them, to make them white again, and then fall off and break their necks?

Steven Chu is a nobel prize winner in physics. That suggests he knows what he is talking about.

Politcal rants, on the other hand......

I love the look of a white roof, although not on every house.

When we replaced our roof 2 years ago we added R14 (2" of foam) and a reflective white coating. I have no way to tell how much the white coating has contributed, but the improvement in our comfort level is considerable. Before the new roof, our AC was unable to cool the house, now we rarely even need to turn it on.

A white roof, often with crushed white rock has long been traditional in places like Palm Springs. I think they look fine.

Of course, we believe in science at our house....

Steven Chu is a nobel prize winner in physics. That suggests he knows what he is talking about.

Exactly... just like they should give Michael Phelps a doctorate in Fluid Dynamics because he won 8 gold medals in swimming.

White roofs save energy. second would be a reflective surface, followed by light colored roofs.
darker colors are the least effecient.
I can tell the difference in my personal home, and
in the work I do..changing the roof color in the software
we use makes a differenc in the overall energy efficiency
of the home.
see below article:

Reflective White Roofing Cuts Energy Costs 20%
Switch to a White Roof Can Reduce Power Bills, Greenhouse Gases
A study released September 9, 2008 by scientists from Lawrence Berkeley National Laboratory in California quantified what traditional builders have known for centuries: that white roofs help deflect the sun's hot rays and reduce the indoor temperature of the building below.

In air-conditioned houses, a reflective white roof helps reduce the amount of heat that reaches the inside of the house, reducing the need for air conditioning. In houses without air conditioning, a white roof keeps the house more comfortable on hot days.

Potential Savings: 20% of Your Home's Annual Energy Use
"White roofs can cut a building's energy use by 20% and save consumers money," says California Energy Commissioner Art Rosenfeld. "The potential energy savings in the U.S. is in excess of $1 billion annually."

While cool roofs significantly reduce a building's cooling load in most climate zones around the world, they can also increase heating costs in winter months by reflecting solar heat back into the air instead of absorbing it as other roofs do. But the energy savings in warm months typically greatly outweigh the extra costs in winter, since less of the sun's heat reaches the earth in winter.

Dramatic Reductions in Greenhouse Gas Emissions
The reduction in electricity use has the added benefit of reducing power plant carbon dioxide emissions. The study estimates that replacing nonreflective, dark roofing materials with a white roof on an average house with a 1,000-square-foot roof would reduce CO2 (carbon dioxide) emissions by 10 metric tons a year.

Reducing the Risk of Blackouts and Brownouts
Energy managers dread the hot, sunny days when millions of air conditioners click on at the same time, straining the power grid and sometimes even causing brownouts or blackouts. Air conditioning demand peaks from mid-afternoon to early evening on hot days, when the sun beats down hardest on air-conditioned houses. White roofs help lighten the strain on the grid by reflecting more of the sun's energy back into space at just the moment when conservation is most needed.

Choosing an Energy-Efficient Roof
If it's time to replace your roof, industry experts recommend looking at four types of energy-efficient roofing materials:

1.Metal roofs. These perform best with a factory-applied polymeric coating that helps the metal radiate the heat away more quickly.
2.Ceramic or concrete roofing tile
3.Roofing membranes
4.White reflective coatings
Check with a professional roofer to see which material fits best with your house. The energy and money savings definitely make it worth the effort to seek out energy-efficient roofing.

Painting the Roof White
If new roofing is financially out of reach, painting the old roof white with special reflective paint called hyperseal paint can work much the same magic. U.S. Energy Secretary Steven Chu recommended this as a way for homeowners to reap significant savings on summertime energy costs.

Read more: http://saving-energy.suite101.com/article.cfm/energyefficient_white_roofs_save_money#ixzz0N3jkLRSL

Read more: http://saving-energy.suite101.com/article.cfm/energyefficient_white_roofs_save_money#ixzz0N3jdQ8P2

Read more: http://saving-energy.suite101.com/article.cfm/energyefficient_white_roofs_save_money#ixzz0N3jXRrJY

This is an old thread, but when posts are so few and they contain so much that is just plain wrong, then I can't help myself.

Dark colored shingles reflect from 5 to 15 % of sunlight, the rest is absorbed into the roof and roof substructure.

White painted shingles reflect 60 to 90 % of sunlight so much less heat energy goes into the roof and substructure. Even if dust and debris accumulate over the course of a few years, the roof will still reflect much more heat energy that a dark colored roof.

When I painted my black roof white, its maximum temperature fell from 185 degrees to 105 degrees. That 80 degree difference is heat that I do not have to block, exhaust, cool, or otherwise deal with. If someone goes to work inside my attic, I no longer have to worry that they will die from heat stroke.

Appearance from the street is not bad. The white roof against the sky appears as natural as a cloud. None of my neighbors have complained.

Now that the roofing material and wood below is cooler, I suspect longevity will be increased since things are no longer being "cooked" and I can easily recoat the roof at any time in the future. I used a breathable coating in order not to trap any moisture which might find its way under the coating.

My complete project cost about $500 in materials with me doing the work, but based on early summer electric use, I should recover this expenditure within 2 years even while I am experiencing cooler summer temperatures inside my house. It's a win-win so far!

A white roof will reflect visible light and therefore lower the temperature of the roof, save energy in a hot climate and extend the life of asphalt shingles but roughly half of the sun's energy is infra red light which is absorbed equally by all colors of asphalt shingles. The issue of roofing color should not be made by itself but in consideration of the entire roof design.

The head of Dragon software (the best voice transcription software, and I work with three of them of them) says that he hires 80 percent physicists because he can teach physicists to program and learn linguistics, but he can't teach linguists to learn physics and program. I don't know much about Steven Chu but I'll bet he pretty good at anything he chooses to be. I wouldn't discount his opinions on energy solely because his Nobel prize is in physics.

In a hot climate the color of a roof, the amount of roof insulation and a radiant barrier reduce heat gain but moving air through an unconditioned attic can draw conditioned air into the attic. A good design depends on balance with insulation being the most important element. Don't get hung up on the other elements; they are secondary.

When you read claims for energy savings ask how well insulated the roof was in the test and where it was located. Often there was a little insulation in the attic floor. For a well insulated roof, color and infra-red transmittance are virtually irrelevant but they can't hurt.

This post was edited by Renovator8 on Fri, Jul 5, 13 at 12:25

If you don't have a white roof, then you are guessing. I have a white roof in Houston and the hottest days are now comfortable. I had insulation before, but the white roof is the icing on the cake.

I understand why people who make their living replacing roofs do not like people going white. Roof temperature dropped by 80 degrees which means the shingle and deck temperatures are far cooler and not being overly stressed by heat. As soon as the sun goes down my roof is actually cool to the touch and at the hottest time of day I can rest my hand on the roof without burning. My ugly roof suddenly looks new again and has a new lease on life.

Dark or white? Easy question for me.

old thread. but white roofs still work well.
not so sure about this though:
"How much will our health care costs go up with all of these people climbing up on their roofs to scrub them, to make them white again, and then fall off and break their necks?"

you could look at it as providing jobs and hire
washing the roof out to someone else.
usually not much scrubbing involved, in my experience.

white roofs combined with air sealing, duct sealing
& good insulation packages...and properly sized
hvac systems...is a good energy savings package.

now if you want to grouse about global warming &
politics..I'm outta here!!! LOL!

So far the rain has done a good job of keeping the white roof washed, but when I am no longer able to maintain my house, I probably will be old enough to not worry about the color of my roof.

In his book, "Roofing Failures" (p. 180), my old friend Carl Cash of the forensic testing and engineering firm, Simpson, Gumpertz and Heger describes the results of tests he conducted on asphalt shingled roofs in 7 locations in the US. The roofs were unvented, vented and vented with wind assist and had both black and white shingles.

He found that the temperature difference between black and white shingles on vented and unvented roofs in different climates varied from .79 to 1.1 degrees F and on vented roofs with wind assist the temperature varied from 1.92 to 2.69 degrees F.

Here is a link that might be useful: Roofing Failures by Carl Cash

This post was edited by Renovator8 on Tue, Jul 16, 13 at 23:34

Built a new construction home on 28.5 acres in a hobby farm subdivision - large acreage plots. Owned the land for 6 years prior to building. The architecture of the home was chosen primarily based upon site topography. Additionally, the structure was situated to achieve a highly desired view.

One year later, a three story, 9,000 square foot home with a white roof sits squarely in 'the view'.

Will defer comments about a white roof...
~bgj

With my white roof, I just had a summer with the lowest electric bills in the eight years that I have had this Houston area house. The drop was so significant that the electric company sent a technician to check the smart meter. When he was finished I pointed to my white roof and he nodded.

I think it is common sense. If it is a hot sunny day and you are going to mow the lawn, do you want to wear a white t-shirt or a black t-shirt?