That's an interesting Idea. To get everybody on board, try to calculate and keep track of savings. Then when enough has accumulated, splurge as a group, treating yourselves to some fun together.
If you tell little Johnny to shut off the light in his closet, when it's not needed, because you need the savings to send him to college some day, I doubt if that will excite him. But promise to spend the savings a weekend at the beach, better chance he'll want to help. And the beach weekend is an outing as a family.
It doesn't even have to be all the savings, but some portion should be for rewarding the troops.
Oh, if you chain smoke, light each butt from the last, save on matches and lighters.