Throughout the design process, it is considered that the condition of intersection between Q, H & E is always performed, so the product of the associated eco-coefficients. For notation simplicity, this product expressed by axpxy may be reduced and replaced by a single factor called "eco-efficiency factor", denoted for example by the Greek letter X. This factor will be inserted into each step involved in the design process and its measured value may be different from one stage to another. For the stage (k), the ecodesign performance is evaluated in relation to the measurement results of the factor X(k) equals to a(k)xp(k)xy(k). For instance, if this factor reaches the sustainable factor i. e., X(k)= X®, the objective required is then attained and the ecodesign condition is fully accomplished for that stage. However, if the factor X(k) fails in stage (k), this will cause a systematic rejection of the material, the process, the method or the service used in that stage. An alternative solution is absolutely necessary before performing the next stage (k+1).