SAFE for energy sustainability - Normalization
The basic indicators are normalized in [0, 1] by linear interpolation between sustainable and unsustainable indicator values, which are specified by international agreements and norms, laws and regulations, and expert opinion. Table 2 gives the upper and lower thresholds of unsustainable values, Uc and υc respectively, and a range [τc, Tc] of sustainable or target values for each basic indicator c. For a given country, let zc(t) be the value of indicator c in year t. The corresponding normalized value is calculated from
\[{x_c}(t) = \left\{ {\begin{array}{*{20}{r}}{0,}&{{z_c}{\rm{(}}t{\rm{)}} \le {\upsilon _c}}\\{\frac{{{z_c}{\rm{(}}t{\rm{)}} - {\upsilon _c}}}{{{\tau _c} - {\upsilon _c}}}{\rm{,}}}&{{\upsilon _c} < {z_c}{\rm{(}}t{\rm{)}} < {\tau _c}}\\{\,\,1,\;}&{{\tau _c} \le {z_c}{\rm{(}}t{\rm{)}} \le T}\\{\frac{{{U_c} - {z_c}{\rm{(}}t{\rm{)}}}}{{{U_c} - {T_c}}}{\rm{,}}\;}&{{T_c} < {z_c}{\rm{(}}t{\rm{)}} < {U_c}}\\{0,}&{\,{U_c} \le {z_c}{\rm{(}}t{\rm{)}}{\rm{.}}}\end{array}} \right.\]Normalization facilitates the comparison and combination of different indicators by assigning the value 1 to best performance and 0 to the worst.
| Basic Indicator | Typea | Thresholdsb | Commentsc,d |
|---|---|---|---|
| aSB = smaller is better; LB = larger is better; NB = nominal is best. | |||
| bυ, τ, T, and U are thresholds of target (sustainable) and unsustainable values. Values in the interval [τ, T] are assigned the sustainability index 1. Values ≤ υ or ≥ U indicate poor performance and are assigned the sustainability index 0. Values in (υ, τ) or (T, U) are scaled in (0, 1) by linear interpolation. | |||
| cMAX (MIN) = maximum (minimum) value over all countries (based on most recent values). | |||
| dEU-14: Austria, Belgium, Denmark, Finland, France, Germany, Greece, Ireland, Italy, Netherlands, Portugal, Spain, Sweden, United Kingdom. These countries and Luxemburg are the countries in the European Union before the expansion of May 1, 2004. Luxemburg has not been taken into account due to its very small population. | |||
| GHG (tons of CO2 equivalent per capita) | SB | T = 0.0075, U = 0.0368 | T is set at the average of EU-14 reduced by 30% in accordance with the EU target of 2020, U=MAX |
| NO2 (μg/m3 of air) | SB | T = 18.2, U = 109.16 | T minimum of EU-14, U=MAX |
| SO2 (μg/m3 of air) | SB | T = 1.33, U = 97.07 | T minimum of EU-14, U=MAX (excluding 1% outliers) |
| PM10 (μg/m3) | SB | T = 6.4769, U = 174.6720 | T=MIN, U=MAX |
| Nuclear waste (tons of heavy metals per capita) | SB | T = 0, U = 0.0593 | T=MIN, U=MAX |
| Access to electricity (percent of population) | LB | υ = 9.0, τ = 100.0 | υ = MIN, τ = MAX |
| Renewable energy production (percent of total primary energy supply) | LB | υ = 0, τ = 20 | υ = MIN, τ = EU target |
| Electricity from oil, gas, and coal sources (percent of total electricity production) | SB | T = 0, U = 100 | T=MIN, U=MAX |
| Energy intensity (kg of oil equivalent per $1,000 GDP, constant 2005 PPP) | SB | T = 50.4970, U = 1176.7054 | T=MIN, U=MAX |
| Energy use (kg of oil equivalent per capita) | SB | T = 66.7045, U = 11,402.0571 | T=MIN, U=MAX |
| Imports (percent of energy use) | SB | T = 0, U = 97.3847 | T=MIN, U=MAX |