This book shows around 25 international houses that are based on modular and prefabrication systems. All of them have ecological advantages in comparison to standard construction systems, since they represent a more effective use of resources and a reduction of construction time and there with costs. All houses are built in factories, carried by road and assembled on site. Thus, building materials can be used more economically and very few refuse is produced during construction. Due to the actual spread of technologies and construction typologies, the international prefabrication industry can deliver up-to-date houses, aesthetically modern, and with an average rank of prizes from very cheap solutions to more exclusive ones, depending on the main material used (wood, steel, galvanised aluminum and concrete).