45 replies to this topic

[Shortpoet-GTD]

Estimates of up to 25 million metric tons of CO-2 could be saved if buildings/homes
had their roofs painted white.
The heat island effect in cities alone could be diminished if commercial (flat) roofs were
painted white.
Info here.

Not all businesses can plant a green roof but everyone can paint them.

Look around your neighborhood-how many dark colored roofs do you see?

[Green Steve]

I certainly haven't ever seen a white rooftop but for that huge a saving I would certainly get behind it - well I would paint my roof if it belonged to me but unfortunately I rent

[artistry]

I think that I read about this being done in other countries. I think it is a great idea. That kind of savings would be fantastic. Let the painting begin.

[still learning]

I just spent a few minutes with Google Earth looking at rooftops.

In San Diego quite a few roofs are light colored.
Just about all roofs are light colored in Yuma and Tucson.
A fair number of light roofs in El Paso.
Practically no residential roofs are light in Houston, but many commercial roofs are.
Likewise Mobile.
Miami iis mixed.

[btatro]

How many white roofs do I see? Absolutely none. I live in Wisconsin, and have never seen a white roof here. Pinkish red, yes, but not white.

[zararina]

The common color of roof here is red.
Obviously very few are aware of the white roof benefit and so, almost no one here have a white roof.

[Shortpoet-GTD]

Manufacturers could easily take the lead on this, and produce more light colors-pale yellows, tans, along with white.
If there sales departments were brought up to speed on the bad side effects of dark colors-
#1 being-retaining heat
they could easily steer more homeowners/ home builders into using the lighter colors.

Homeowners can also repaint them themselves, or hire a contractor, but special paint has to be used,
and not all roofs are asphalt shingles. Clay tiles are common too-but maybe a lighter stain could be applied?
Metal roofs would be easy to repaint.
Most, I would guess are unaware of the benefits.

[joeldgreat]

Ours was painted dark red. I think there are several reasons for doing this. Dark ones hides the dirts, whereas you can easily spot dirts in light colored house. This adds to the feeling (and effort) that you need to repaint it after several months. We also develop a stereotypes that roofs should be painted with dark colors as this was the mindset given to us by paint manufacturers. Seeing TV commercials about how the house looks good when painted with dark colors. But if we shift our mindset, then there's nothing wrong painting our house with white colors. Now, I'm considering the idea on my next roof paint job.

[Isabellas2007]

I have never heard of the white roofs before. I know this could be a huge challenge, but it could be worth it if it helps the planet. For me, I have a tan colored roof which works out really well. The fact that I live outside of the hotel can help out as well, but each time I go to the city I hate the heat difference, even the small town close to me of about 5000 people has a higher temp of about 5 degrees.

[Shortpoet-GTD]

Painting individual homes will help for sure, but I think the main thrust of this project is aimed at commercial
buildings that are hundreds of square feet of black asphalt.

Those humongous a/c units are sitting in the direct sun for one, and two, they're constantly fighting the heat
waves rising from the black asphalt.

If all commercial buildings were painted white, or a light color-
and
the a/c units were shaded from the direct sun, it would reduce their bills and the units would last longer.

The heat island effect in cities can raise the temperatures significantly.
White roofs, shading a/c units and planting trees or planting a green roof with just grasses or a garden,
reduces the heat island effect.
Green roofs may need extra bracing for the added weight-white roofs don't.

Btw-In one NYC study, for example, done in June-July 2011 where some roofs reached temps of 170 degrees-
roofs painted white were 42-43 degrees cooler.
Source

[MakingCents]

What is the purpose behind the black roofs?  I had heard once that in winter-like states it can help to draw in the solar heat in the winter.  Do we think this holds merit?  I would be interested to see a study done on the benefit of that- making the house warmer naturally vs. the heat they give off in the summer...

May also depend on if you keep your house on the cold end of htings or warm end of things.

[dissn_it]

This is the first I have heard of this but you would think commercial buildings would be happy to pay for white paint if it saves them money in the long term.
I live in a colder climate and in the winter, ALL the roofs are white.

[Shortpoet-GTD]

MakingCents, on 02 June 2012 - 08:07 AM, said:

What is the purpose behind the black roofs?  I had heard once that in winter-like states it can help to draw in the solar heat in the winter.  Do we think this holds merit?  I would be interested to see a study done on the benefit of that- making the house warmer naturally vs. the heat they give off in the summer...

May also depend on if you keep your house on the cold end of things or warm end of things.

In Canada perhaps, and maybe a few northern states but with climate change, we're not getting winters
like before.
No snow or tons of it. Black ice storms or no rain. Milder temps or bitter cold. It's all changing.
But yes, dark roofs "collect" the sun's heat better for the colder months.

[Shortpoet-GTD]

NYC gets it.
http://www.motherjon...-climate-change

[SFloridaMike]

I live in Miami and have a white roof--about 1 in 4 homes in our neighborhood have them. Nearly all all of these are older, sloped roofs with gravel locked in place using a white elastomeric coating.

[E3 wise]

 White roofing 2.JPG   18.48K   0 downloads

Living in South Florida we became aware of this type of roofing almost 20 years ago.  We recommend cool roofing for all of our building design work and feel that the added savings in cooling costs are well worth the investments.  

One of the most popular options we incorporate is an elastic PVC material that is very strong but flexible and has a 20-25 year life span.  Another product is made by Somay roof mastic which not only cools the roof but also waterproofs it and helps prevent blow off in high winds.  They advertise that in 36 years no roof that has been applied correctly has lost its roof in a hurricane. In Hurricane areas we recommend this product also and have had good results.

Heres a little background info. to show why we recommend cool roofs for our customers.

Cool Roofs consist of materials that reflect the sun’s energy from the roof’s surface, and also have high emissivity, which allows them to emit infrared energy. Cool roofs can reduce the temperature of the roof’s surface by up to 100 degrees Fahrenheit. This reduction in temperature reduces the heat transferred into the building and can reduce the building’s peak cooling demand by as much as 15 percent.

Cool roofs provide both immediate and long-term savings for you as the building and/or business owner:

• Energy cost savings through a reduction in summer cooling demand and other utility’s
  
• Increased lifespan of your roof, as well as the entire building structure, its cooling equipment and the rest of its subcomponents
  
• Reduced building and roof maintenance and replacement cost
  
• Tax advantages
  
• Improved comfort for your employees and customers
  
• Reduced greenhouse emissions and pollution due to the urban heat island effect (the temperature difference between an urban area and its surrounding rural areas, caused by human development of the land surface with materials that retain heat).

In order to improve energy efficiency, Wal-Mart stores built since 1999 in the US have white roofs.

On June 15th, 2010, Philadelphia’s City Council unanimously passed a cool roof bill, requiring all new construction in the City to use reflective roofing materials that meet or exceed Energy Star cool roof standards on all new commercial and residential buildings with no or low slopes. The City of Philadelphia has set its sites on becoming America’s greenest city and joins several other cities requiring Energy Star cool roof standards; New York, Chicago, and the state of California.

[E3 wise]

I forgot to include that the PVC material is a special application for flat roofing and is used mostly in commercial applications, Somay is used in both commercial and residential.

[artistry]

Are people still using shingles for their roofing.? Are they still dark colored? That would be a good place to start, if they have not gone the way of the wind.

[FamilyTreeClimber]

I saw a documentary about this some time ago.  You would think light colors would be very popular in warm areas.

I don't see many light colored roofs in my area of the San Francisco Bay Area.  From what I notice on my walks the roofs are shingles.  Tar and gravel (rock) roofs were very popular for awhile here, but I'm not seeing much of them lately.  I don't think there are any white roofs in my neighborhood.  In the more expensive areas (not around here), tile in the material of choice.

[Shortpoet-GTD]

White roofs are up to 42 degrees cooler than dark, according to a NASA survey and can reduce demand on a/c
units up to 20%.
http://www.nasa.gov/...s/ny-roofs.html
http://www.care2.com...for-a-year.html