(372e) Involving the Water-Energy-Waste Nexus in the Optimal Design of Total Integrated Residential Complexes
To solve this problem, a superstructure is proposed where all the possible configurations was included, as well as its possible solutions. Due to the number of objectives, it is not possible to find a solution to the problem through a Pareto curve and there may be a lot of dissatisfaction with one of the objectives. Therefore, for the solution of the problem, a different multistakeholder tool is used to find a balance between the objective functions and give a reasonable solution to the problem, is considered a residential complex located in the central-west region of Mexico, which consists of 1 440 households.
The proposed multiobjective optimization model was coded and solved in the software GAMS. The model consists of 1 098 continuous variables, 10 binary variables, and 3 570 constraints. The model includes nonconvex terms, so to solve the model in GAMS we need a global optimization solver; in this case, we selected Baron because a local solver did not provide a good solution. The weights for the objective functions for each of the scenarios of the case study for the multistakeholder approach were generated randomly in the software MatLab through the Latin hypercube function. Assigning random weights to the objective functions is only a representative option to show the effect of prioritizing one objective and to show the trade-offs of the considered objectives.
The dissatisfaction of each of the objective functions and the total dissatisfaction for all the scenarios were calculated. The scenario with the lowest total dissatisfaction represents the most attractive solution for this problem, where the individual dissatisfaction for the objectives are 14% for the total annual cost, 9% for the fresh water consume, 7% for the CO2 emissions, the return of investment is near for the upper bound with 99% of dissatisfaction, while the environmental impact and the process route health index are in their best solutions with 0% of dissatisfaction.