The structure of the SAFE model for energy systems is shown in Fig. 21. It is assumed that the overall energy sustainability (OSUS) of a country is a combination of two primary components: ecological sustainability (ECOS) and human sustainability (HUMS). The ecological input comprises two secondary components: air quality (AIR) and soil quality (LAND). The human components of energy sustainability are social (ACCESSIBILITY) and economic (PRODUCTION, CONSUMPTION, SECURITY). Each secondary component is assessed using certain basic indicators which are the inputs of the system.

The sequence of data processing is similar to the original SAFE model:

1. Collection of available data
2. Normalization in [0, 1]
3. Exponential smoothing
4. Data imputation
5. Fuzzification
6. Fuzzy assessment of sustainability
7. Sensitivity analysis and decision making.

References

• Grigoroudis, E., V.S. Kouikoglou, and Y.A. Phillis (2013). A fuzzy paradigm for the sustainability evaluation of energy systems, in: F. Cavallaro (ed.), Assessment and simulation tools for sustainable energy systems: Methodology and applications, Springer, New York, 205-224.