[RE-wrenches] Personal project: roofing colors

[Matt Tritt]

William,

My first company truck was a 1970 Land Rover 109 Diesel, that had 
something called a "tropical roof", which was a second roof surface 
(aluminum like the rest of the car) mounted on standoffs about 2" above 
the actual cab roof. There were also scuttle flaps that allowed inside 
air to be pulled out of the interior space by airflow, but the inside 
roof of this car always remained at ambient temperature. I thought this 
was such a cool idea (pun intended) that I incorporated the design into 
a chicken coop I had at the time to try and keep the poor girls inside 
from becoming baked chicken - it worked really well.

If you use a double roof as described, it doesn't matter what the 
roofing color is, as long as the eaves are open and you have a good 
ridge vent to allow proper circulation, and an air gap of about 3". The 
only issue being the added cost, of course!

Matt T

Joel Davidson wrote:

> William,
>
> There's lots of good technical data (and also wild advertising claims) 
> on the www if you google "cool roofs". Smooth white roofs (metal or 
> non-metal) reflect heat well. Several years ago the US Bureau of 
> Standards tested composition shingles and found that so-called white 
> comp shingles got almost as hot as black shingles because of their 
> granular texture and asphalt subsurface.
>
> 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%.
> ...from http://www.fsec.ucf.edu/en/publications/html/FSEC-PF-336-98/
>
> Joel Davidson
>
> ----- Original Message ----- From: "William Miller" 
> <wrmiller at charter.net>
> To: "RE-wrenches" <re-wrenches at lists.re-wrenches.org>
> Sent: Wednesday, September 24, 2008 9:05 AM
> Subject: [RE-wrenches] Personal project: roofing colors
>
>
>> Friends:
>>
>> I have an energy question on a personal project.  We are adding two 
>> rooms to our house and it is time to select roofing colors.  Nothing 
>> will match the weird comp shingles already on our roof, so we are 
>> going to not match and re-roof the rest of the house later.  In the 
>> meantime, I need to pick a shingle color.  How much difference does a 
>> lighter roof color make here in our inland California (Mediterranean) 
>> climate?  We get over 100F frequently in the summer.
>>
>> Thanks for your insight.
>>
>> William Miller
>>
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