Brown versus White Roof?

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I'm getting a new roof on my house. I'm considering changing to brown shingles (Owens Corning Desert Tan) from white shingles.
If anyone here has any experience about increased air conditioning costs after going to a darker roof, I would like know how much your bill went up (or didn't).
Particulars would be most helpful, such as climate, and how well the attic was insulated.
My own particulars: Louisville KY, ranch house, low pitched hip roof, poorly insulated attic. Air conditioner ducts do not pass through attic. House gets a fair amount of shade from trees located on East, South, and West sides. But they are Maples, and I don't want to assume they will last the next 30 years.
--
Tony Sivori

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On 5/25/2012 11:46 AM, Tony Sivori wrote:

Improving attic insulation and ventilation will have a much bigger effect on your heating and air conditioning costs. My new house is over twice the size of my old house. The winter heating and summer cooling costs are lower in the new house than in the old house.
The attic in the old house was like an oven in the summer. The attic temperature in the new house is barely warmer than outside. The attic is so well ventilated you can feel a breeze moving through it.
LdB
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LdB wrote:

That is what my miserable little scuttle is like, I'd guess it is 120 up there mid-day in the summer.

--
Tony Sivori

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Tony Sivori wrote:

You're not even close. Think 140+.
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HeyBub wrote:

Ok, I decided to check. I put a wired inside / outside thermometer up there this morning.
It is now 3PM local, 90 and sunny outside, the roof is in 30% shade from trees. The attic temperature is 121.
So I'd guess it could easily exceed 130 on the hottest days of summer, but exceeding 140 might never happen in my particular attic.
--
Tony Sivori

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Tony Sivori wrote:

I can believe that if you live in the Dakotas. My attic reached 150 before a massive effort to reduce the temp was undertaken. The effort consisted of four wind turbines, a ridge vent, and a SIGNIFICANT amount of fascia vents.
Now it seldom gets above 130.
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I was a roof rat for 20+ years, so I have a bit of experience with them. First & foremost, decide on the color/style based on curb appeal. It is said 40% of the curb appeal on a home is based on roof color & style. Don't count on the color to keep your home cool, if you must upgrade your insulation factors & venting, do so. The granules used on shingles is based on opacity for UV rays. Most manufacturers use a quality granule. Choose the color based on your liking, not someone else's. For example, I always despised the desert tan & white, it always looked _cheap_ to me, but then it's not my home. Consider a style, which would fit well, most architectural shingles add to value over the standard 3 tab. Also consider a shingle, which has mold inhibitors added at the manufacturer, the price difference isn't that much considering a roof is an investment. Also, consider a color, which will be around for awhile, don't go with a _new_ color or fad. Having a bundle or 2 shingles as extras isn't a bad idea, but having to keep a square or 2 around takes up space.
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My house was built in 1983 and had a concrete tile roof on it. I am in the Tampa Bay area - and after Andrew in 1992 the codes for roofs changed. When it came time to replace mine I could not afford a tile roof (each piece must be nailed at all four corners). Anyway, I got GAF - good for up to 120mph winds - light brown color. There were vents at each end of my house - in the attic - and they were boarded up. The new roof has a ridge vent.... the costs of a/c hasn't changed any because of the roof being different. I used to have a man come by once a year and spray the tile roof so I wouldn't get mildew or mold -- and I don't need to do that anymore. At least not yet ... the papers that came with the roof said it was treated for fungus and all that. So far it's working....had it since 2007.
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Gomba wrote:

I'm thinking about adding a ridge vent.

I don't like the look of the white either. I do like the Desert Tan (in the eye of the beholder, I guess), but not so much that I would want my cooling bill to be $10 or $20 higher every summer month.

This is a hail damage insurance job, so I can afford some out of pocket to upgrade to a better shingle than the 3 tabs that are now in place.

Do you have any opinion about Owens Corning Oakridge versus GAF Timberline?
--
Tony Sivori


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On 5/26/2012 12:25 AM, Tony Sivori wrote:

Next roof I'm considering doing the south side of my roof white and the front north (street facing) side whatever color my wife wants. My neighbor got his roof done in white shingles and I think it looks decent.
From what I've gathered, the color can make quite a difference in attic temperature.
Attic insulation, and proper vents, is what you really need though.

--
X-No-Archive: Yes


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To me, Owens has always been more of a product any consumer can get their hands on. _My_ choice was always Certainteed, then GAF.
I've been away from the products for a good 10 years. At that time, Owens didn't have a hip & ridge cap. You basically would try to match a conventional 3 tab color, to their architectural shingles. Don't know if they ever decided to make a hip & ridge for their architectural's. Could look it up, but am feeling a bit lazy. :)
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Gomba wrote:

OC does make a hip and ridge cap, it is in one the brochures that I got with an estimate. In the photos, they don't look as thick as the ones from GAF.
--
Tony Sivori

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I would go for a light tan or grey color, depending on house color
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wrote:

Forget everything else. Insulate the attic. Cheap and you can do it yourself. The savings there is far more than the difference in roof color.
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Ed Pawlowski wrote:

No two ways about, I do need and would benefit from more attic insulation. But to get to the recommended R value it will run about $700 even as a DIY job, so I don't consider it especially cheap.
Doing the math if it were to cut my total energy usage 20% (I doubt if I would save that much), it would take 7.3 years to break even on the $700 up front cost.
So I would like to do it someday, but for now it is not at the top of my priority list.
--
Tony Sivori

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On 5/26/2012 12:11 AM, Tony Sivori wrote:

$700.00 seems a bit high for insulation. Wouldn't hurt to look around a bit more. Check the people that blow in cellulose insulation.
Around here lumberyards will rent you an insulation blower when you buy the bags of insulation from them. You can do it with the help of a neighbor or two. Look around maybe you can find someone else that wants to add insulation. You can help each other and split the cost of the blower.
Don't let the bean counter math dissuade you. Energy costs will go up but so will the cost of insulation. You will be in the same boat a few years from now.
The math only looks at the money. It doesn't take into account that your house will be more comfortable. That's not worth anything to a bean counter but it's why people say to themselves " I wish I had done that years ago."
If the insulation save money in energy costs it also save wear and tear on your air conditioner. That will save you a few bucks as well.
LdB
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Kentucky?? I could see roof color being a factor in Florida - or the Caribbean or Equatorial Africa, but not in a temperate inland area like Kentucky. Best just to insulate that attic floor(yes insulation does keep from transferring into rooms below it in summer), and either install proper ridge vent or end vents. Remember the only purpose of a roof is to keep moisture/wind of the lived in part of a home - unless the attic is to be lived in as well. And do not insulate between the roof rafters, unless the last part of my last sentence applies. :)
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Tony Sivori wrote:

Executive summary:
1) proper venting and a shit-load of insulation can (or will) make shingle-color irrelavent in terms of heat-load to the home's A/C system
2) consider using a radiant barrier underlayment under the shingles - regardless of shingle color
3) I suspect that shingle color DOES play a role in shingle life-span (darker shingles will get hotter, probably will have shorter life)
4) I've paid more attention to the homes in my area (great-lakes area) with light-colored asphalt shingles, many of which have trees nearby, and I see little to no evidence of staining / discoloration. The extent to which this staining is assumed to happen might be over-estimated.
A study (reproduced at the very bottom of this post) gives these conclusions:
- The greatest influence on roof temperature is geographic location.
- The direction a roof faces has the second greatest influence on average roof temperature
- The color of roofing materials influences the mean temperature of a roof system slightly less than direction
- Ventilating the area under a roof deck reduces the average temperature 0.5 degrees Celsius (about one-third the influence of the direction or color and one-thirty-sixth the influence of geographic location). Even with wind assistance, ventilation reduces average roof temperature about half as much as using white rather than black shingles.
- Within the ranges studied, slope has the least influence on average shingle temperature.
Remember, that study is looking at roof temperature, not ambient air temperature inside the attic. They conclude with this statement:
"Many shingle manufacturers provide warranted products that are widely distributed and are of many colors and exclude from warranties those shingles installed on unventilated decks. This exclusion has no justification; the variations in geography, direction and shingle color have greater influences on average temperature than the degree of ventilation."
The first study that I'm reproducing (immediately below) is focused on attic air temperature and household heat-load.
================== Monitored Summer Peak Attic Air Temperatures in Florida Residences http://www.fsec.ucf.edu/en/publications/html/FSEC-PF-336-98/index.htm
The field data was from a variety of residential monitoring projects which were classified according to intrinsic differences in roofing configurations and characteristics. The sites were occupied homes spread around the state of Florida. There were a variety of different roofing construction types, roof colors and ventilation configurations.
The ambient air temperature was obtained at each site by thermocouple located inside a shielded exterior enclosure at a 3-4m (10-12 foot) height. The summer 15-minute data from each site were sorted by the average ambient air temperature into the top 2.5% of the observations of the highest temperature. Within this limited group of observations, the average outside air temperature, attic air temperature and the coincident difference was reported.
Attic air temperatures vary considerably depending on roofing type, color and ventilation.
It is worth noting that light gray or "white" asphalt shingles have a measured solar absorptance of approximately 75% as opposed to true reflective roofing systems which have absorptances less than 30% (Parker et al., 1993B). Dark gray shingles have a solar absorptance of about 90%.
http://www.fsec.ucf.edu/en/publications/html/FSEC-PF-336-98/images/attic-5.gif
Figure 5. Influence of asphalt shingle color on measured average attic air temperature at two adjacent Homestead, Florida sites (HO2 and HO5) during the summer of 1996.
Conclusions
Although the 21-house data set is not large enough to comprise a statistical sample, it does suggest some important influences on summer attic design temperatures in Florida. Light roof colors, deck-mounted radiant barriers, added attic ventilation and tile roof construction were all shown to reduce peak attic air temperatures. A simple characterization of the collected data would be as follows:
Table 6 Comparison of Coincident Attic to Ambient Design Temperature Difference
Case / Attic Design Temperature
Shingle roof soffit vent only / Ambient + 35F (19.4C) Shingle roof soffit and ridge venting / Ambient + 22F (12.2C) Shingle roof Radiant Barrier soffit vent only / Ambient + 25F (13.9C) Tile roof / Ambient +10F (5.6C) White roof / Ambient -1.5F (0.8C)
A simple calculation illustrates the importance of controlling the peak attic air temperatures measured in this study. As example, consider a residence on a a peak summer day at 95F served by a three ton cooling system with a sensible capacity of 27,000 Btu/hr and an EER of 9.0 Btu/W. The assumed residence has a 1,800 square foot ceiling with R-30 attic insulation.
Supply ducts typically comprise a combined area of ~25% of the gross floor area (see Gu et al. 1997, Appendix G, and Jump and Modera, 1994), but are only insulated to R-4. With the peak attic temperatures for a shingle roof with poor ventilation estimated at 130F, and 75 maintained inside, a UA dT calculation shows a ceiling heat gain of 3,300 Btu/hr. With R-4 ducts in the attic and a 57 air conditioner supply temperature, the heat gain to the duct system is 8,212 Btu/hr if the cooling system ran the full hour under design conditions-- more than twice the ceiling flux. However, the magnitude of both ceiling and duct heat gain is 43% of the air conditioner's design sensible cooling load. Thus, attic heat to ceiling and attic to duct heat gains are a major portion of the design cooling load for residences.
In the example the attic related gains are also responsible for a 1.28 kW increase in peak air conditioning electric demand. As a contrast, with a white roof system, the estimated attic air temperature would be 93.5F, with a total ceiling and duct heat transfer rate of 5220 Btu-- a reduction of 6,300 Btu/hr and a drop in electrical demand of 700 W if the system was at design capacity with the dark roof. ================= See also:
http://www.newton.dep.anl.gov/askasci/eng99/eng99520.htm
http://findlayroofing.com/blog/roof-color-atlanta-home-temperature /
============== (the following material does not consider shingle-color in terms of imacting shingle-lifespan)
http://www.findlayroofingnc.com/resources/item/shingle-color-north-carolina-home-temperature
Shingles Follow The Rules - Black is Hotter Than White
No one questions if black shingles get hotter than white shingles, but many people have wondered what the temperature difference really is. Shingle manufacturers have been especially interested in answering this question, and many have performed tests to determine the number.
Their test conditions and results vary, but the temperature difference between a white and black shingle, when exposed to the same amount of sunlight, is generally stated to be from 20 to 40 F.
Without a doubt, 40 F is a big difference. But keep in mind that this number is likely taken from a small number of specimens, and the testing was done under very specific conditions. The point is, these numbers aren't good enough to suggest you race out to buy all the white shingles in town today.
Every Shingle Color Stays Cool With Good Roof Ventilation
Test data is useful information to have, but the most important data comes from actual rooftops and homes. And the real rooftop data clearly shows that shingle color is a small player when it comes to shingle temperature.
Any professional roofing contractor will tell you that choosing a shingle color should be based on personal preference more than on temperature concerns. Proper roof ventilation is the real key to keeping your shingles cool and making them last as long as possible. There are countless dark-colored roofs across the country that are still going strong after 15 years, to prove the point.
What About The Temperature Inside My North Carolina House?
With good roof ventilation, the impact of shingle color on roof and attic temperatures becomes somewhat insignificant. The presence of insulation in an attic makes shingle color practically irrelevant, in terms of interior room temperatures.
Put another way, there is no need to worry about temperature effects when choosing a shingle color for your home. Instead, you should work with your roofing contractor to make sure that your roof has the ideal amount of ventilation.
By installing the proper combination of ridge and soffit vents, for example, your can keep your North Carolina roof cool during even the hottest of days. A cool roof keeps your shingles cool, and allows them to achieve their longest possible life. At the same time, you will be keeping your home cooler all summer long.
=============== What's the value of ventilation?
A study of asphalt shingles demonstrates ventilation may not be as important as other variables
http://www.professionalroofing.net/archives/past/mar02/feature2.asp
The topic of asphalt shingles splitting and cracking has received much attention lately. Asphalt fiberglass shingles have been experiencing vertical splits, as well as horizontal splits in exposed tabs. These dislocations, called thermal splits, are the subject of a great deal of litigation, including class-action lawsuits. The splits are not associated with quality of installation. Rather, the splits occur in shingles where self-sealing adhesive firmly adheres the shingle tabs and a shingle's tear strength is low or inadequate to withstand a thermally or mechanically induced load.
Whenever asphalt fiberglass shingle manufacturers are faced with thermal-splitting problems, one excuse they usually offer is that the area under a roof deck was not ventilated properly.
This excuse is offered not because there is any evidence of a cause-and-effect link between thermal splitting and ventilation but because shingle warranties (all the shingle warranties listed in NRCA's 2002-03 Steep-slope Roofing Materials Guide) specifically exclude warranties in the case of "inadequate attic ventilation." This is based on the premise that shingles applied to decks over unventilated attics will be unacceptably hotter than shingles applied to decks over properly ventilated attics and have significantly shortened service lives as a result of the increased temperature.
Lawyers say impractical or unreasonable contract or warranty provisions may not be supported by court decisions. The following information reveals results from a study we conducted that investigated the reasonableness of the "inadequate attic ventilation" exclusion in warranties.
Some parameters that can influence roof temperature are geographic location, color, exposure orientation, slope and degree of attic ventilation. We report the means (averages) of the maximum and average annual temperatures of the roofing materials for each combination of these parameters.
(lots of material describing a multi-city study not reproduced here)
Conclusions
The following conclusions are based on data from our numerical model:
* The greatest influence on roof temperature is geographic location. The mean roof temperatures for Miami and Green Bay, Wis., for example, differ by 18 degrees Celsius.
* The direction a roof faces has the second greatest influence on average roof temperature (in excess of 1.44 degrees Celsius in the east through south-to-west range studied, but the real difference is greater because other directions, such as north, will be cooler).
* The color of roofing materials influences the mean temperature of a roof system slightly less than direction (1.45 degrees Celsius average for these parameters).
* Ventilating the area under a roof deck reduces the average temperature 0.5 degrees Celsius (about one-third the influence of the direction or color and one-thirty-sixth the influence of geographic location). Even with wind assistance, ventilation reduces average roof temperature about half as much as using white rather than black shingles.
* Within the ranges studied, slope has the least influence on average shingle temperature.
Many shingle manufacturers provide warranted products that are widely distributed and are of many colors and exclude from warranties those shingles installed on unventilated decks. This exclusion has no justification; the variations in geography, direction and shingle color have greater influences on average temperature than the degree of ventilation.
However, ventilation should be recommended to remove the small quantity of moisture in a roof system; it can prolong the life of a wood deck even if it does not extend the life of shingles.
Carl G. Cash is a principal with Simpson, Gumpertz & Heger Inc., Arlington, Mass., and Edward G. Lyon is a senior staff engineer with Simpson, Gumpertz & Heger.
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Information overload <grin> !!!!
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my dad and family live in phoenix where the vast majority of shingles are white for less attic heat and longer shingle life
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