Assessment of energy efficiency measures using multi-objective optimization in Portuguese households

This paper presents an optimization model to identity the best set of retrofitting measures applied to four different regions of Portugal; Lisbon, Porto, Bragança and Évora. The main objective is to maximize the annual energy savings, expressed in Euros, while minimizing the initial investment expressed also in Euros, considering the retrofit strategies as decisions variables and evaluating their effect in the usage of space heating and cooling and costs, depending on the chosen technology. A multi-objective genetic algorithm coded in MATLAB© to solve the optimization problem. Different energy efficiency measures are considered, such as the improvement of U-values in external walls and windows through the application of insulation materials, the change of lighting fixtures and refrigerator model to reduce the electricity consumption, and the usage of PV panels for self-consumption, and the use of Heat Pumps for space heating and cooling. The fitness function is subjected to different constraints related with the fulfillment of the demand, the physical limitation of household space, the capacity to comply with the heating and cooling needs, and the non-negativity nature of the variables. The best set of retrofitting options are presented, the budget to implement them and the amount of achieved energy savings.