This concept allows for the fact that our economy relies upon natural capital (air, plants, biosphere) and social (human) capital to function. The problem is that much of what our economy needs does not appear on the cost sheet so isn’t valued as it should be.
The following video explains this idea in simple terms
This next video is a fantastic fast-based gallop covering the related idea of green design
Your hero could be an accountant except that these days all accounting is based on triple bottom line accounting methods that assign costs based on social, environmental and financial costs. Alongside the main plot, perhaps he/she could be agonising over what value to assign to a product that involved destroying habitat of the great crested newt, or resulted in a 13% increase in incidence of mild asthma for 2000 residents living near a factory.