Of course, initially it is obvious that it is a combination of frugal and green which are words that in many ways already compliment each other, so you may be thinking we don't need a whole new word. But they are not always in sync with one another, for example I would love to run my house on solar power but currently that is not in my budget.
On the flip side it may be frugal to buy a new dress when it it on sale but not a very green choice if we already have ten dresses in our closet that we never wear. So. while there is quite a lot of over lap they are not the same thing and hence the need for a new word. Besides it is fun to make up words, at least I think so, and I have permission from an actual lexicographer. Watch this Ted talk by Erin McKean and you may even be inspired to make up your own word.
So my new word is
Frugreen: the conscious and conservative use of resources to have a minimal impact on the earth and ones bank account, incorporating a healthy balance of need versus want.