Re-Black roofs


#1

There was a rooftop temperature study on that a few years back and the difference is minimal if there is sufficient ventilation. without any ventilation it can vary by 40 degrees.


#2

So if I spray painted a person black and nailed them to the roof by their clothing in the middle of a sunny summer day they would be hotter than the white painted person unless they opened their mouth?


#3

I did read something like that J something around 4 or 5 degrees.


#4

If the mouth is the outtake what will be the intake ??

:shock:


#5

I think it’s about 7 degrees differance at most.


#6

Yeah what about working with balck shingles. It sucks.
Its atleast 15 degrees hotter up there then on the ground. And they melt and scuff. Imwalking around the roof like a duck.


#7

We used to get the first 7 or 8 feet up the slope installed, then grab a hose with one of those nozzles you put on the end and spray the roof down during the summer as we were working. OMG that was so nice, it kept us cool and kept the roof cool too. = )


#8

Mostroofs i do are new construction so there is no hose or water.
We usaully by a bag of ice a day for the cooler. Thats the only thing that keeps us cool.


#9

Note to Mod: if you’re reading this, my bbcode didn’t fly… feel free to edit if possible.

Happy reading:

The first few are not 100% what you’re looking for, but close… read all the way through:

http://www.prnewswire.com/cgi-bin/stories.pl?ACCT=104&STORY=/www/story/02-07-2001/0001422284&EDATE=Florida%20Power%20&%20Light%20study%20done%20in%20Gweedo’s%20back%20yard%20(in%20conjunction%20with%20USF)

[quote]A white, galvanized metal roof should save a customer who lives in an average-size 1,770 square foot home approximately $128 or 23 percent annually
in cooling costs, compared with a dark gray shingle roof on the same home.[/quote]


http://64.233.167.104/search?q=cache:r8IAc57tQ-wJ:www.dca.state.ga.us/intra_nonpub/Toolkit/Guides/HeatDevdAreas.pdf+Heat+Signature+of+Black+Roof&hl=en&ct=clnk&cd=4&gl=us&client=opera

[quote]The Lawrence Berkeley National Laboratory
(enduse.lbl.gov/Projects/pavements.html) provides information on the cost of porous pavements through a project called “Life-Cycle Costs and
Market Barriers of Reflective Pavements.” Similarly, planting trees costs money, but can save on long-term energy costs. For example, an elementary school in Alexandria, Va. replaced a typical black roof with a reflective roofing system and energy costs for the school dropped from an average of $121,000 to $90,000 per year. (Building Operation Management, 2000)[/quote]


Looks like the Canuck’s have the straight dope:

http://irc.nrc-cnrc.gc.ca/pubs/cbd/cbd047_e.html=Canadian%20Building%20Digest

http://irc.nrc-cnrc.gc.ca/images/cbd/047f01e.gif

So, there ya go.


#10

So the 40 degrees I had heard was pretty close. I thought it was a ARMA study though. The key thing was that with proper ventilation the difference could be minor.

RooferJim