The problem of the optimal sizing of the storage zone shown in Figure 5.24 consists in the determination of the measurement of length Lx and width Ly (the height of the warehouse is in fact determined by the height of the storage system). Let m be the required number of storage locations; αx and αy the occupation of a unit load along the directions x and y, respectively; wx and wy, the width of the side aisles and of the central aisle, respectively; nz the number of storage locations along the z direction allowed by the storage system adopted and v the average speed of a picker. The decision variables are nx, the number of storage locations along the x direction, and ny, the number of storage locations along the y direction.