The act of construction consumes an enormous amount of resources. Materials are extracted, processed, shipped, modified, and assembled to create a building, with every step consuming energy. That investment is only sustainable if the building then serves its function for many years. In the U.S., real estate financing and development models often lead to planned twenty year lifespans for new buildings. In Europe, where resources, including land and energy, have been scarce for centuries, they invest in buildings designed to last over a hundred years. Making buildings stronger and tougher leads to longevity, as well as improved safety and comfort for the occupants.