Posted: Nov 28, 2009 under Math & Science

Description: Sustainability Performance Index (SPI) is a measure of the degree by which a system solves a problem or set of problems for which it was design to solve and the degree by which it avoids causing a completely different set of problems elsewhere within it. So the problem resolution-avoidance measure is the key to the sustainability of any system, especially the type of system designed to solve human problems. The calculator assigns 100% resolution value to each aspect of the problem in the resolution pool. In practice, this value is the sustainable value (SV) of each aspect of the problem and could range between 0 and 100%. As the shown in the calculator, SPI is calculated by consolidating all SV’s for all aspects of the problem in the resolution. Note that the Sustainability Capacity (SC) of any system is a relation between its resulting SPI and deficit that may exist. As such and consequently a system a 100% SPI means that there is no deficit in the system which as you know is always carried from one system working cycle to the next. A Sustainable Capacity of a system with an SPI less than 100% always incurs a deficit equals to its Sustainable Balance (SB).