what is life life cycle assessment?

Answer 1

For assesing the full life-cycle cost of a product you need to account for it's complete impact on people & planet. Most market economists try to avoid including costs that can be passed on to society as a whole or in the future, so they can make most profit now

for a good example see Cradle to Cradle design by
William McDonough, Michael Braungart.
Cradle to Cradle is a manifesto calling for the transformation of human industry through ecologically intelligent design. Through descriptions of environmentally benign design principles and compelling examples of innovative business strategies already reshaping the marketplace, the authors make the case that present the industrial system can generate goods and services that create ecological, social and economic value.

Answer 2

Are you refering to a life cycle assessment of living things or of a inanimate objects such as a building?