@HerraBRE
This goes both for big and small solutions alike. The lack of a shared way of measuring the environmental impact is problematic but I'm not sure is solvable: factors are a lot, and hard to reduce in simple formulas.
Odum gave it a good shot, ending up with a system which is interesting but IMHO not usable.
Measuring carbon footprint in some other way, such as the direct impact, is oblivious to the indirect effects... it's a topic I'm thinking a lot lately, and in some sectors (I mainly know the agricultural one) some standards are being developed which may be a good start.