EARTH ARCHITECTURE IN NORTH OF PORTUGAL – CASE STUDY FROM VERNACULAR TO CONTEMPORARY

1. Introduction
It can be said that sustainable construction means “not to build” as since the Neolithic that Man started to exploit resources more than nature by itself can give. Of course that this scenery got much worst after the Industrial Revolution and especially in the end of the twentieth century, giving rise to a post-industrial environmental consciousness, that lead to three main operative strategies on developed countries, as represented on Figure 1: new techniques with natural materials and traditional techniques with industrialized materials (low-tech approach); and new materials with new techniques using the minimum materials possible (light-tech approach). Nowadays, it can be concluded that a really sustainable use of resources is only still possible in those areas of the planet that were isolated from the consumer society, where the human relationship with nature allowed a simple life in harmony with the natural surroundings, as in a pre industrial revolution scenario, even if we consider that the industrial revolution arrived much later to construction industry. Even in industrialized countries, such as in Portugal, till approximately 50 years ago, heavyweight materials present in construction were still in direct relation with the natural resources available in the subsoil. The heavyweight parts of the building were mostly the structural envelope walls, in stone, earth or brick; that could easily arrive to 1000kg/m2. In comparison, pavements and coverings in structural timber only weight between 50 and 150kg/m2. A typical view of the inner part of this type of building can be seen on Figure2. The lithological map of the Portuguese territory shows that the walls of traditional constructions were in general the same of the surrounding subsoil, as it can be seen on Figure 3. […]