Ferrocement is resource efficient because it uses minimal rebar and concrete to produce ‘thin shell’ structures. The resulting curved members are somewhat similar to trees and plants. This is the opposite of straight concrete walls that rely on massive thickness to gain strength (and cost way more money).
One of the best sites for learning about ferrocement is Steve Kornher’s Flying Concrete website. Steve has gone to great lengths to provide lots of photos and detailed information about ferrocement.