It is not the scarcity of resources that constitutes environmental problems, but their use, the physical throughput of our economies. Material flows are a proxy for the totality of the unspecific environmental risks from human activities. As a strategic goal, an increase of the life-cycle-wide resource productivity by a factor 10 is suggested, including the materials bought and sold and the not-valued materials: we have to take into account the product itself and its "ecological rucksack". Material flows are best measured at the input side of the economy, where their number as well as the number of entry gates is limited. Thus here regulation and economic incentives can work more efficiently and less bureaucratically than today. The material intensity of products and services can be expressed as MIPS, the material input per unit of service, and as TMR, the total material requirement on the macro level, an important element in physical input–output tables.
Dematerialization, MIPS and factor 10 : physical sustainability indicators as a social device
(1999)
In the discourse about sustainable development, "constant natural capital" is frequently referred to as a criterion for ecological sustainability. But what is "natural capital"? The concept will be analyzed by presenting arguments in favour of using the term and different versions of sustainability (strong and weak). Subsequently, a critique of the "natural capital" concept is brought forward, from an ecological as well as from an economic perspective. Following this critique, the use of material inputs and the material input per unit of service (MIPS) as a measure for the environmental impact potential is suggested. Dematerialisation is understood to be an alternative management rule for sustainability. In conclusion, a change of perspective is proposed. Due to the conceptual and measurement problems associated with the "constant-natural-capital" criterion (which refers to a stock), it seems more reasonable from a scientific as well as from a practical perspective to add flows (i.e. material inputs) to a decision criterion for whether a development is sustainable or not.