  Understanding sustainability through modeling involves one of the complex and
interdisciplinary activities where mathematics plays a key role. We provide
arguments favoring the need for developing global models for measuring the
status of sustainability. A global model (applicable in broader perspective)
and global sustainability indices are proposed which can be used with
real-world data. The solutions of the proposed Partial Differential Equations
(PDEs) are blended with the weight functions of Riemann Stieltjes integrals to
capture the differential importance of sustainability associated factors. The
ideas, methods, and models are new and are prepared for handling
multi-dimensional and multi-variate data. A practically adaptable formula for
measuring the sustainability index is developed with few key variables. We
provide a real-world example arising in civil engineering applications with a
numerical example to demonstrate our models.
