These Pennsylvania-German bank barns were American adaptations of barn forms found in the high valleys of eastern Switzerland. This traditional form evolved, beginning in the 1500s, in response to the harsh Alpine weather. It proved to be a very effective design for the cold winters of the northeastern United States and, over the years, many features of the design were adapted to American barns. The bank barn was efficient because large amounts grain and hay could be processed and stored above the livestock area, and then tossed down to the animals when needed, with gravity doing all the work. The projecting forebay side of the barn provided shelter to the stalls below, keeping the doorways clear of snow and ice. The bank barn is also an early example of passive solar design. Generally oriented to a southern exposure, the projecting forebay provided cooling shade to the livestock during the summer when the sun was at a high angle, and provided heat and sunlight during the winter, when the sun was at a lower angle.