LSMFT wrote:
There is a push to cool the earth, save energy and keep your home
cooler at less cost to have white roofs. Especially in the cities to
reduce heat islands.
What about northern states where we heat more than air condition.
Should we go to white roofs or black roofs or middle colors?

Let's think about white roofs and summers:

Whatever the color of the roof, it's going to absorb SOME heat. Eventually
it will absorb as much as it can. The trick is to have a system that can
shed as much heat as is absorbed. A white roof will merely absorb heat at a
slower rate than, say, a black roof. That means that the rest of the system
(fans, soffit vents, etc.) need not be as robust as if the rest of the
ventilation system had to deal with the heat transfer of a black roof.

Meanwhile, a white roof will almost immediately look like hammered goose
droppings due to staining and dirt.

For a black roof - winter combination, the reverse heat transfer process is
in play. A black roof will shed heat from the house at a slower rate than a
white roof because the black roof is absorbing heat from the sun faster than
its white counterpart.

So, then, to answer your question: Roof color will make SOME difference in
energy costs but that differerence depends more on the quality of the rest
of the system (ventilation, insulation, etc.), than the color of the roof.
Specifically, with sufficient ventilation, an attic in summer won't get much
hotter than the outside air, irrespective of the roof color. With pitiful,
or no, ventilation, the attic temperature may be a hundred degrees higher
than the air outside!