I actually think the look of that white roof is really cool! For hot weather states especially white roofs seem to be the way to go!
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7
White roofs.
Started by Shortpoet-GTD, May 30 2012 03:16 AM
45 replies to this topic
#22
Posted 01 October 2012 - 02:39 AM
It's funny sometimes, the things that we learn on this forum, and how they translate into how we view everyday things.
I was watching P. Allen Smith on PBS-my gardening guru and at the end of his shows, he does a "virtual"
landscape make-over for homeowners that have sent in their pictures.
A lady send in a picture of new construction-bare yard
but two things struck me.
It had a black roof (what?)
and it was mcmansion sized.
Why aren't builders educated enough to use white or light colored roofing tiles on the homes?
It makes you wonder what kind of insulation was incorporated, in the walls, with the windows, in the attic.
I know people want choice, but why is black, brown or other dark colors still being offered to builders for roofing
material?
I was watching P. Allen Smith on PBS-my gardening guru and at the end of his shows, he does a "virtual"
landscape make-over for homeowners that have sent in their pictures.
A lady send in a picture of new construction-bare yard
but two things struck me.
It had a black roof (what?)
and it was mcmansion sized.
Why aren't builders educated enough to use white or light colored roofing tiles on the homes?
It makes you wonder what kind of insulation was incorporated, in the walls, with the windows, in the attic.
I know people want choice, but why is black, brown or other dark colors still being offered to builders for roofing
material?
#23
Posted 12 October 2012 - 06:07 PM
Many homes I see by me are clay tiles. Some have a few solar panels for the water heater. I have also seen the solar panel roof vent that sucks out the hot air in the attic which cools the house down. I know my brother in law put one on his home in CA. They aren't that expensive either. It would be great if downtown, the commercial buildings had their roofs painted white and had solar panels.
#24
Posted 15 October 2012 - 01:56 PM
I have never heard of painting roofs white. I don't know if there are some legal limitation to painting your roof white in my city because of helipads near local children hospitals. Please check with your home association too before making the change. I don't want anyone to get a fee!
#25
Posted 07 December 2012 - 03:37 PM
In sunny. hot areas it can make a huge difference in how much electricity you use for A/C but in reality, I think that a white roof will only be white for a couple of years unless you pressure clean it. They likely could put something in the paint/coating to eliminate the mold but that's just more chemicals in the environment.
#26
Posted 08 December 2012 - 04:04 AM
r. zimm, on 07 December 2012 - 03:37 PM, said:
In sunny. hot areas it can make a huge difference in how much electricity you use for A/C but in reality, I think that a white roof will only be white for a couple of years unless you pressure clean it. They likely could put something in the paint/coating to eliminate the mold but that's just more chemicals in the environment.
And why would a roof get moldy?
The sun's rays act as a disinfectant.
#27
Posted 18 December 2012 - 12:09 PM
Roofs get moldy in high preipitation areas. I've seen very moldy roofs in California and especially in Washington. The sun will kill it if it gets enough exposure but trees etc. often block enough to negate the effect. Moreover, though the mold is killed, once it's on a roof it comes back every year worse than the last.
Wood roofs seem worst, followed by asphalt and cement tile roofs which are nearly as bad. Steel roofs, tend to turn green as the mold eats the paint. My recycled rubber shinge roof grows mold in the seams which dies in the summer, but it's back in the seams again next year. This is the only roof material I've seen that doesn't deteriorate over time as the mold has nothing to eat. What is in the seams is trapped dust, etc.
My roof started out light green but has dirtied over time and no, the rain does not wash it off! Actually it's meant to mimic slate and it is developing the patina of natural slate. Unfortunately the company has discontinued it.
Wood roofs seem worst, followed by asphalt and cement tile roofs which are nearly as bad. Steel roofs, tend to turn green as the mold eats the paint. My recycled rubber shinge roof grows mold in the seams which dies in the summer, but it's back in the seams again next year. This is the only roof material I've seen that doesn't deteriorate over time as the mold has nothing to eat. What is in the seams is trapped dust, etc.
My roof started out light green but has dirtied over time and no, the rain does not wash it off! Actually it's meant to mimic slate and it is developing the patina of natural slate. Unfortunately the company has discontinued it.
#28
Posted 21 December 2012 - 07:29 AM
I recall this subject being discussed a few years ago, someone even suggested white road surfaces might be a good idea.
It's a basic form of geoengineering for the birds.
I used to paint my dog's pen roof white, but only to keep their accomodation cool.
It's a basic form of geoengineering for the birds.
I used to paint my dog's pen roof white, but only to keep their accomodation cool.
#30
Posted 22 December 2012 - 03:50 AM
Be assured that I'm not posting the following because I believe it or want anyone else to, it's an alternative theory that should be considered:
October 28, 2011
White Roofs Could Raise Global Temperatures
A worldwide conversion to white roofs may actually warm the earth by about 0.07 C (0.13 F), according to Stanford University researchers.
In Effects of Urban Surfaces and White Roofs on Global and Regional Climate, in the Journal of Climate, Mark Z. Jacobson and John E. Ten Hoeve combined land use, vegetation, albedo (reflecting power of the earth’s surface) and soil-type data to model temperatures 20 years into the future, estimating the effects of white roofs on climate.
They found that a worldwide conversion to white roofs, accounting for their albedo effect only, would cool population-weighted temperatures by about 0.02 C but raise overall global temperatures by much more. The researchers said that ...
http://www.environme...l-temperatures/
October 28, 2011
White Roofs Could Raise Global Temperatures
A worldwide conversion to white roofs may actually warm the earth by about 0.07 C (0.13 F), according to Stanford University researchers.
In Effects of Urban Surfaces and White Roofs on Global and Regional Climate, in the Journal of Climate, Mark Z. Jacobson and John E. Ten Hoeve combined land use, vegetation, albedo (reflecting power of the earth’s surface) and soil-type data to model temperatures 20 years into the future, estimating the effects of white roofs on climate.
They found that a worldwide conversion to white roofs, accounting for their albedo effect only, would cool population-weighted temperatures by about 0.02 C but raise overall global temperatures by much more. The researchers said that ...
http://www.environme...l-temperatures/
#31
Posted 22 December 2012 - 04:26 AM
We all know (or should know) that white or lighter colors reflect heat; black or dark colors absorb heat; making it hotter.
"White roof's can reduce summer energy use by 10-30%, saving money and preventing pollution.
They can reduce the urban heat island effect by 1-2 degrees, (area level's) enough to lower peak energy demand, and
reducing the risk of brownout's and blackout's."
http://ecopreneurist...roof-at-a-time/
http://whiteroofproj...climate-change/
http://whiteroofproj...cientific-data/
http://thinkprogress...year/?mobile=nc
"The dark, sunlight absorbing surfaces of some New York City roof's reached 170 degrees on July 22, 2011; a
day that set a city record for electricity usage during the peak of a heat wave.
But in the largest discrepancy of that day, a white roofing material was measured at about 42 degrees cooler."
http://www.nasa.gov/...s/ny-roofs.html
http://whiteroofproject.org/
"White roof's can reduce summer energy use by 10-30%, saving money and preventing pollution.
They can reduce the urban heat island effect by 1-2 degrees, (area level's) enough to lower peak energy demand, and
reducing the risk of brownout's and blackout's."
http://ecopreneurist...roof-at-a-time/
http://whiteroofproj...climate-change/
http://whiteroofproj...cientific-data/
http://thinkprogress...year/?mobile=nc
"The dark, sunlight absorbing surfaces of some New York City roof's reached 170 degrees on July 22, 2011; a
day that set a city record for electricity usage during the peak of a heat wave.
But in the largest discrepancy of that day, a white roofing material was measured at about 42 degrees cooler."
http://www.nasa.gov/...s/ny-roofs.html
http://whiteroofproject.org/
#32
Posted 22 December 2012 - 06:24 AM
Shortpoet-GTD, on 22 December 2012 - 04:26 AM, said:
We all know (or should know) that white or lighter colors reflect heat; black or dark colors absorb heat; making it hotter.
"White roof's can reduce summer energy use by 10-30%, saving money and preventing pollution.
They can reduce the urban heat island effect by 1-2 degrees, (area level's) enough to lower peak energy demand, and
reducing the risk of brownout's and blackout's."
http://ecopreneurist...roof-at-a-time/
http://whiteroofproj...climate-change/
http://whiteroofproj...cientific-data/
http://thinkprogress...year/?mobile=nc
"The dark, sunlight absorbing surfaces of some New York City roof's reached 170 degrees on July 22, 2011; a
day that set a city record for electricity usage during the peak of a heat wave.
But in the largest discrepancy of that day, a white roofing material was measured at about 42 degrees cooler."
http://www.nasa.gov/...s/ny-roofs.html
http://whiteroofproject.org/
"White roof's can reduce summer energy use by 10-30%, saving money and preventing pollution.
They can reduce the urban heat island effect by 1-2 degrees, (area level's) enough to lower peak energy demand, and
reducing the risk of brownout's and blackout's."
http://ecopreneurist...roof-at-a-time/
http://whiteroofproj...climate-change/
http://whiteroofproj...cientific-data/
http://thinkprogress...year/?mobile=nc
"The dark, sunlight absorbing surfaces of some New York City roof's reached 170 degrees on July 22, 2011; a
day that set a city record for electricity usage during the peak of a heat wave.
But in the largest discrepancy of that day, a white roofing material was measured at about 42 degrees cooler."
http://www.nasa.gov/...s/ny-roofs.html
http://whiteroofproject.org/
#34
Posted 23 December 2012 - 07:46 AM
Shortpoet-GTD, on 23 December 2012 - 05:27 AM, said:
Keep a black roof, if you think all the studies are false.
1. I didn't say I think all the studies are false.
2. I don't have a black roof.
#35
Posted 23 December 2012 - 06:27 PM
I really do wish I had more time to comment on many of the issues talked about here at Alt Energy Shift, problem is I travel every week, in the last three weeks I have been to Germany, Japan and Korea working with companies developing alternative energy sites. I am the Director of Integration for Environmental Power & Water Generation; we are a design and integration firm for Alternative Energy, Hydrogen Energy and Water recovery, generation and reverse osmosis. However on this issue I felt it was important to make a comment, because this is one area that we stress to our customers to reduce energy consumption. So let’s begin with environmental studies and the peer review process.
Ah, you have to love the peer review process in science, although it takes sometimes years to form a long term conclusion. The biggest disadvantage is that lay people who are not familiar with the process think that just because an idea appears in a scientific journal than it must be the overall truth.
What is actually the case is that ideas are tested and then put out for review to identify possible flaws or reinforce conclusions. Let me state for the record that the peer review process is a long drawn out process. How do I know so much about the process, well my wife and I have participated in the peer review process for the National Renewable Energy Laboratories Hydrogen, Wind to Hydrogen and Solar to Hydrogen programs since 2008. Usually the process takes 9 month to a year to complete for each study and then follow up review of outcomes that take 6 months are more. Meaning we are still working on studies from 2011 for the NREL that will be released to the public in 2013.
So onto the Subjects of White Roofs. Firstly I must say that some of the benefits of White roofs were overhyped by some for the amount of benefit to the Urban Heat Islands effect on overall climate change. Early on several publications touted this as a way to help cool the planet by up to a full degree Fahrenheit. Now let me make clear that most of this was not scientist making the case but News Publications looking to get people to read their publication and some politicians looking for that elusive silver bullet that has never and will never exist, meaning no one thing is going to take care of every issue with climate change. Now regarding the study cited by Earthling.
Mark Z. Jacobson & John E. Ten Hoeve - Effects of Urban Surfaces and White Roofs on Global and Regional Climate -Jacobson's computer modeling concluded that white roofs did indeed cool urban surfaces. However, they caused a net global warming, largely because they reduced cloudiness slightly by increasing the stability of the air, thereby reducing the vertical transport of moisture and energy to clouds. Meaning that no moisture was being released to cause normal cooling of the air that occurs from land and vegetation releasing water. For climate change deniers this seemed like another way to counter mans effect on, or ability to, affect climate change. Yet this was not the conclusion of the study, the true conclusion was the following.
Which was - While white roofs may not be of much use in reducing global warming as touted by publications and poloticians, Jacobson did identify that installing photo-voltaic solar panels were of use as they reduce emissions of fossil fuels from greenhouse gas electricity-producing power plants, but they also reduce sunlight absorbed by buildings because they convert sunlight to electricity.
As the photo-voltaic panels do not reflect the sunlight back to the air, unlike white roofs, reflected light is available to be absorbed again by pollutants in the air, thus preventing the creation of more atmospheric heat.
Now let’s interject some ideas that are being researched but have not made it into the public forum yet.
1. Jacobson’s study is comparing buildings to land and vegetation meaning that to truly measure the affect you would have to tear down every building in the world ( In computer models of course) to measure the true effect, which is not going to happen and makes the whole study irrelevant, because it will not occur in the real world.
2. The study does not calculate - The study did not examine a potential benefit of white roofs in reducing air conditioning use during hot weather. Since this can reduce the amount of energy use by a minimum of 20% and up to 30%. Since saving that amount of energy would reduce emissions by the same amount, this could thereby offset the heating effect of emissions significantly. Meaning that the tradeoffs for reducing energy using by 20% to 30% and warming the earth by .13F is never considered by the study.
3. That reflected radiation will somehow lead to an increase in temperature, over and above what already would have occurred when that heat radiation warmed the black rooftop upon the instant of its arrival over the white roof that reflects it after it has been changed in wavelength structure caused by striking the white roof.
I want to relate something that I do not mean to be a personal attack or indictment on Earthling but just a statement of motivation. He has let me know that he feels that a forum is a place for debate, and since he has participated in debating since he was 15, he enjoys fostering said debate, also that he feels strongly that man has had either a minimal or no effect on climate change. A view that I personally do not agree with but maintain that he is entitled to hold.
So in this case and I am making an outrageous analogy to demonstrate a point. (Meaning I am sure he does not truly believe what I am about to say), but for the analogies sake of debaters motivation.
If I were to advocate that Humans should not eat our children, a true debater would counter that eating our children is a good way to reduce exploding population rates.
Once again not an indictment, but just an attempt to help others understand the motivation, it’s nothing personal it just debating.
Jeff Moore
Ah, you have to love the peer review process in science, although it takes sometimes years to form a long term conclusion. The biggest disadvantage is that lay people who are not familiar with the process think that just because an idea appears in a scientific journal than it must be the overall truth.
What is actually the case is that ideas are tested and then put out for review to identify possible flaws or reinforce conclusions. Let me state for the record that the peer review process is a long drawn out process. How do I know so much about the process, well my wife and I have participated in the peer review process for the National Renewable Energy Laboratories Hydrogen, Wind to Hydrogen and Solar to Hydrogen programs since 2008. Usually the process takes 9 month to a year to complete for each study and then follow up review of outcomes that take 6 months are more. Meaning we are still working on studies from 2011 for the NREL that will be released to the public in 2013.
So onto the Subjects of White Roofs. Firstly I must say that some of the benefits of White roofs were overhyped by some for the amount of benefit to the Urban Heat Islands effect on overall climate change. Early on several publications touted this as a way to help cool the planet by up to a full degree Fahrenheit. Now let me make clear that most of this was not scientist making the case but News Publications looking to get people to read their publication and some politicians looking for that elusive silver bullet that has never and will never exist, meaning no one thing is going to take care of every issue with climate change. Now regarding the study cited by Earthling.
Mark Z. Jacobson & John E. Ten Hoeve - Effects of Urban Surfaces and White Roofs on Global and Regional Climate -Jacobson's computer modeling concluded that white roofs did indeed cool urban surfaces. However, they caused a net global warming, largely because they reduced cloudiness slightly by increasing the stability of the air, thereby reducing the vertical transport of moisture and energy to clouds. Meaning that no moisture was being released to cause normal cooling of the air that occurs from land and vegetation releasing water. For climate change deniers this seemed like another way to counter mans effect on, or ability to, affect climate change. Yet this was not the conclusion of the study, the true conclusion was the following.
Which was - While white roofs may not be of much use in reducing global warming as touted by publications and poloticians, Jacobson did identify that installing photo-voltaic solar panels were of use as they reduce emissions of fossil fuels from greenhouse gas electricity-producing power plants, but they also reduce sunlight absorbed by buildings because they convert sunlight to electricity.
As the photo-voltaic panels do not reflect the sunlight back to the air, unlike white roofs, reflected light is available to be absorbed again by pollutants in the air, thus preventing the creation of more atmospheric heat.
Now let’s interject some ideas that are being researched but have not made it into the public forum yet.
1. Jacobson’s study is comparing buildings to land and vegetation meaning that to truly measure the affect you would have to tear down every building in the world ( In computer models of course) to measure the true effect, which is not going to happen and makes the whole study irrelevant, because it will not occur in the real world.
2. The study does not calculate - The study did not examine a potential benefit of white roofs in reducing air conditioning use during hot weather. Since this can reduce the amount of energy use by a minimum of 20% and up to 30%. Since saving that amount of energy would reduce emissions by the same amount, this could thereby offset the heating effect of emissions significantly. Meaning that the tradeoffs for reducing energy using by 20% to 30% and warming the earth by .13F is never considered by the study.
3. That reflected radiation will somehow lead to an increase in temperature, over and above what already would have occurred when that heat radiation warmed the black rooftop upon the instant of its arrival over the white roof that reflects it after it has been changed in wavelength structure caused by striking the white roof.
I want to relate something that I do not mean to be a personal attack or indictment on Earthling but just a statement of motivation. He has let me know that he feels that a forum is a place for debate, and since he has participated in debating since he was 15, he enjoys fostering said debate, also that he feels strongly that man has had either a minimal or no effect on climate change. A view that I personally do not agree with but maintain that he is entitled to hold.
So in this case and I am making an outrageous analogy to demonstrate a point. (Meaning I am sure he does not truly believe what I am about to say), but for the analogies sake of debaters motivation.
If I were to advocate that Humans should not eat our children, a true debater would counter that eating our children is a good way to reduce exploding population rates.
Once again not an indictment, but just an attempt to help others understand the motivation, it’s nothing personal it just debating.
Jeff Moore
#36
Posted 24 December 2012 - 05:31 AM
In my postings on white roof's I never meant to imply that it would have a (direct) effect on global warming but
that by reducing the use time of a/c units in a city environment, it could in the long term, reduce emissions.
I view it as lessening the heat of the area, making it more comfortable.
that by reducing the use time of a/c units in a city environment, it could in the long term, reduce emissions.
I view it as lessening the heat of the area, making it more comfortable.
#37
Posted 24 December 2012 - 11:13 AM
You are not the only one on the boards and my post was not directed at you except the "keep the black roof" one.
It seems that no matter what I say, you argue.
And I'm sure you'll argue you that too, but I don't have the time for negative.
It seems that no matter what I say, you argue.
And I'm sure you'll argue you that too, but I don't have the time for negative.
#38
Posted 24 December 2012 - 12:42 PM
While I am for the idea of anything that is eco-friendly, I would worry about the glare of a white roof. It would be practically blinding on a sunny day. Can you get the same effect with another color roof? Most rooftops are covered in tar paper. Is it really practical to paint them?
#39
Posted 25 December 2012 - 05:54 AM
Earthling, on 25 December 2012 - 01:10 AM, said:
Glare can be a major problem, on a sunny day it's a pain to go onto out top patio, because I painted it with a white waterproof coating to keep the dining room cool in summer.
Tar paper?
Tar paper?
Asphalt shingles.
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