The boys get hot and bothered over crawlspaces & exterior window-frame insulation. Bit of a history of crawlspaces across the US, plus just what crawls should and should not do. And then Steve takes the lead on his favorite "dumb idea: over-insulating window frames. Plenty of ways to improve the thermal performance of windows, but except in very cold climates, our industry has much bigger fish to fry.
Building America Solution Center: Crawlspace
BSI-115: Crawlspaces - Either In or Out
LSU La House crawlspace
GBA Q&A involving window frame insulation (illustrating how tricky over-insulating the frame can be and also butt up against water management):
Pete Yost blog on Thermal Buck