Developed by a Romanian environmental group, they are made from 97% recycled materials and boast a range of energy-saving features — as well as energy-creating options such as solar panels.The dwellings are said to be available in several shapes and sizes, and combine rustic modular design with multiple energy saving and producing technologies. But despite a blaze of publicity, it is hard to track down anyone who has actually seen, far less tried out, one of the homes.

They range from a small unit with just 48 square-meters (516 sq ft) usable floor space (plus attic), up to a relatively sizable model suitable for a family of five, with a main area floor space of 100 square-meters.