The main condition of ecodesign can be reached when the interaction between Q, H, E aspects yields a common area of intersection between these aspects, i. e., Qt^Ht^E. The original diagram (Figure 2a) shows health, quality and environment as three separate aspects that operate independently from each other. Joining the Q, H, E aspects gives rise to a new diagram fulfilling the ecodesign condition (Attaf, 2007) that is characterised by the subset F resulting from this intersection (Figure 2b). The three dots (л) above the character F are only a brief description of the diagram illustrated in Figure 2a, showing interaction between health, quality and environment aspects. In other terms, the three dots represent the three pillars that characterise the basic elements of the sustainable development concept, as discussed above (Figure 1).
Depending on the resultant area of interaction, an optimisation process can be applied to
subset F to maximise this area. If optimisation is highly improved (F = Fmax ), then the future diagram illustrated in Figure 1c is achieved and the searched objective is reached, however.