Yes they do. First of all, saving energy is in itself a reward. Moreover, that's easily gameable by simply comparing yourself to a group of strangers at their energy efficiency house. Airline miles is kinda a hard one, except for the people in that group, competing there (and I'm sure there is), and as far a s random stuff...I'm here in large part because every once in a while I wonder if I can't get a few upvotes on hacker news, hopefully by saying something helpful or insightful, of course.
Saving energy doesn't instill a sense of achievement. Nobody has a bucket list with an item that says "Save as much energy as I can". It just doesn't inspire anyone. Sorry if that's your startup idea.
