The Sustainable Process Index (SPI*) was developed in the 1990s at TU Graz by a team of scientists (substantially by Ch.
It provides an encompassing evaluation that distinguishes sharply between fossil and renewable energy (as Global warming potential does) but taking other emissions to soil water and atmosphere into account as well.
The SPI takes the whole life cycle into consideration starting from mining of raw materials to further transformation and production of goods to recycling to disposal of waste.
The earth’ surface and the atmosphere are complex buildings several compartments have to be considered for a comprehensive ecological evaluation.
Practically this is defined with maximal rates of material and energy flows which can be absorbed by natural sinks of biosphere.
The SPI aggregates partial footprints from mass, energy and emission inventories of every sub-process and refers them to the end product.