One of the interesting side effects of putting a bunch of solar panels on my roof was the shade they provide (they sit about 4" above the roof) and that small gap of air made the attic significantly cooler than before the panels were installed. With these on the 'north side' of the roof (not with water plumbing, just providing a 5 degree C temperature difference) that would be helpful in the Bay Area.
When we built our house we put the actual metal roof several inches above the roof. The actual roof decking NEVER gets hotter than the ambient air temperature (115F max here in Texas). Solar panels or any form of shade structure (including trees) accomplish the same thing.
Shingles or metal directly on a roof heats the house substantially but is cheaper (costs less in labor). That is why we still do it. (Just like dark roofs look "nice" so we still do that too).
Great link, and with this material you would get 5 degrees C below ambient on their underside, so nearly 9 degrees F lower.
Putting the shingles directly on the roof has benefits like keeping water out, and a floating roof (like my panels) is much more susceptible to wind damage (either to create a sail out of them). The 'old school' fix was of course sod roofs. If you put enough thermal mass between the roof and the interior you avoid significant heating.
What about capturing heat form the sun in the winter? Bay Area is a good example for that with sunny but cold days. Would those pockets of warmth we find in winter from sheltered sunny areas and attic spaces be reflected away too? It seems to me that capturing power from the sun in the summer and storing in maybe possible in the future local batteries is preferable to reflecting away the power? Or both?
Good question, I suppose if you mounted them as strips like a shutter (but with 180 degrees of rotation in the long dimension) you could have strips that were black on one side and this material on the other. When you want heat you turn the black side out to the sun, when you want cooling you put the reflective side out.
One of the interesting side effects of putting a bunch of solar panels on my roof was the shade they provide (they sit about 4" above the roof) and that small gap of air made the attic significantly cooler than before the panels were installed. With these on the 'north side' of the roof (not with water plumbing, just providing a 5 degree C temperature difference) that would be helpful in the Bay Area.