## 2 Materials and Methods
### Definition of New Integrated LCA+C2C Categories
* \(\mathrm{FEI(t_{0})}\), the first FEI indicator obtained for the product, i.e., the first period coinciding with the date of market launch (first design). * \(\mathrm{R}\), number of redesigns in which a strategy has been applied to improve environmental, social or economic performance. The FEI macro-indicators are classified into three groups that organize the results of eco-efficiency and eco-effectiveness; any of these are candidates to be evaluated with \(\mathrm{IP_{\%}}\) and \(\mathrm{IP_{T}}\) indices. These are described below: (1) efficiency; (2) consistency; (3) sufficiency. * Efficiency (Ey): This corresponds to the best environmental and social performance result of the product obtained. This provides information on the improvement achieved between the different product versions (expression (8)) and the changing trend for the LCA+C2C endpoint categories (Qk) (expression (9)). The use of this macro-indicator will minimize the impacts of the system, reducing the causes of the problem. \[\mathrm{E_{R\%}}=\frac{\mathrm{Q_{k}(t_{e})-Q_{k}(t_{e}-1)}}{\mathrm{Q_{k}(t _{e}-1)}}\] (8) \[\mathrm{E_{T}}=\frac{\mathrm{Q_{k}(t_{e})-Q_{k}(t_{0})}}{\mathrm{R-1}}\] (9)
* Consistency (Cy) or Effectiveness: This macro-indicator evaluates the cyclicity of the system and is composed of three complementary and proportional parameters. These can be expressed in Kg or %. CC (Cyclicity) quantifies the cycle-closing capacity of the system; ER (Energy Recovery) determines the energy recovery of the product with valorization strategies; and LCV (Loss of Cyclical Value) indicates the loss of resources, due to mismanagement of the end of life. These are calculated with expressions (10), (11) and (12). These indicators will also be subject to periodic evaluation with expressions (6) and (7). \[\mathrm{CC}=\mathrm{ReLU}+\mathrm{ReLU}+\mathrm{ReLU}\] (10) \[\mathrm{ER}=\mathrm{RV}\] (11) \[\mathrm{LCV}=1-\mathrm{CC}\] (12) where \(\mathrm{ReLU}\) are the reused system outputs (kg, %), \(\mathrm{ReM}\) are the remanufactured system outputs (kg, %), \(\mathrm{ReC}\) are the recycled system outputs (kg, %) and \(\mathrm{RV}\) are the energy revalued system outputs (kg, %). * Sufficiency (S): This is a metric of positive impact or creation of value. This implies that, apart from reaching zero-impact strategies, the solution must include plans for regeneration after previously caused damage, i.e., strategies to contribute to the planet's recovery. It is quantified from the C2C Global Score (C2C\({}_{\mathrm{GS}}\)) and economic indicators. Firstly, regarding the C2C Global Score (C2C\({}_{\text{GS}}\)), the input data for the calculation are the results obtained in the C2C certification for each category. These are weighted according to the certification milestone (Basic, Bronze, Silver, Gold or Platinum) using expression (13). \[\text{C2C}\ _{\text{GS}}\ =\frac{1}{5}\cdot\sum_{i=1}^{n}(\text{B}_{i}\cdot 0.1+ \text{Br}_{i}\cdot 0.25+\ \text{Sv}_{i}\cdot 0.5+\ \text{G}_{i}\cdot 0.75+\ \text{P}_{i}\cdot 1) \tag{13}\]  
where:  
* \(i\), each category analyzed in the C2C certification. C2C\({}_{i}\) = {1,2,3,4,5} = {material health, material recovery, energy, water, social}. * \(\text{B}_{i}\), score obtained in each category \(i\) at the basic level: \(\text{Br}_{i}\), score of each category \(i\) in the bronze level; \(\text{Sv}_{i}\), score of each category \(i\) in the silver level; \(\text{G}_{i}\), score of each category \(i\) in the gold level; and \(\text{P}_{i}\), score of each category \(i\) in the platinum level. * Considering \(0\leq\text{C2C}_{\text{GS}}\leq 1\). With the limits: [0, 0.75] negative impact creation, (0.75, 1) zero impact and [1] positive impact creation. Secondly, regarding the direct and indirect economic indicators, the Continuous Improvement Plan (CIP) must be analyzed from an economic point of view. Direct economic criteria (system costs) and indirect economic criteria (costs resulting from the impact of the system) are used.