Manual picker-to-parts order picking systems are predominant in brick-and-mortar retail logistics. While flow-oriented approaches in operations management focus on performance and quality as primary outcomes, recent research aspires to integrate layout design and storage assignment with the ergonomic strains of workers.

In this work, we apply mathematical models that allow layout design and storage assignment optimization by taking pickers’ energy expenditure into consideration. The objective is to find the position of the storage base that guarantees the lowest possible energy expenditure for the human pickers. This is achieved through a proper storage assignment based on the picking frequencies of the products. The innovation we introduce with respect to the previous research, is to allow the storage base to be placed out-centered with respect to the U-shaped corridor. Computational experiments are carried out on random and real-world datasets. The results indicate that positioning the storage base on one side, leading to asymmetric configurations, can clearly lead to superior ergonomic settings.