Ecological Footprint
1Productive land and water we occupy to produce all the resources we consume and to take in all the wastes we make
Reference: Our Ecological Footprint, Mathis Wackernagle and William Rees
Another model, the footprint, explain it.

Newspaper example…for instance, it takes a certain number of acres to grow a tree, and run a paper mill, and produce the chemicals for the ink…you can take all these and estimate how many acres it takes to make your morning paper…Lay the paper out on the floor…if it wasn’t recylcled, it takes about the area of the sheet of paper…