Bill,
All very good questions. Up north where the winters are long and snowy,  many 
people believed that black roofs helped to melt the snow faster. They soon  
discovered that ice would back up in the gutters (because they were colder) and 
 destroy the roof line by creating ice and snow dams.
Roofing materials by nature are black. Coal tar pitch and asphalt are  black. 
Getting them to appear white requires the addition of a lot of  pigmentation 
and is cost prohibitive.
Today we have everything from PVC's, TPO's and a myriad of other products  
which are now all available in white. White roofs (cool roofs) can reduce you  
A/C load by as much as 35%. Reducing the load means your A/C units will run 
less  and last longer. White roofs do nothing for helping to heat a building. 
That's a  function of the building "envelope" and insulation. Cool roofing 
systems  eliminate most of the expansion and contraction which destroy conventional  
roofing systems. 
As always, I am willing to share my tremendous wealth of information for a  
small fee. Send rum.
 
Rummy
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