Foccaccia is a particularly good place to sub whole wheat for white flour
because you're not using a loaf pan and getting depressed if the whole
wheat loaf doesn't rise quite as high.....that's a big part of the reason
why I love making flatbreads of all kinds, because they're more forgiving
of my mistakes....although the more times I read and reread Peter
Reinhart's books, the fewer mistakes I make!
You'll find lots of suggestions out there for converting white flour
recipes to whole wheat. I routinely do the following:
--substitute whole wheat flour for white flour weight-for-weight;
--add 10-15% additional liquid: usually I add the amount called for in the
recipe, mix briefly, then check the hydration before adding a little more
water;
--give the whole wheat flour a little more time to hydrate between the
initial mixing and serious kneading;
--don't worry about the windowpane test, but rely on how supple and soft
the dough feels;
--and if I'm trying for the very lightest bread, I'll add 1-2T gluten flour
per 500g/1 lb/3C flour.
Diane Brown in St. Louis