The same goes for most green clap twaddle. High-E windows sound good, but cost a fortune. How much will purchasing and installing them cost? How much will you save on your monthly heating bill? How many months will it take for you to get back your investment? Wouldn't putting up a $20 set of solar curtains or an $80 set of venetian blinds work just as well?
Everything must be subjected to rigorous cost/benefit analysis, and not adopted because it sounds good or makes you feel good.