Buildings are accountable for over 40% of energy use in OECD countries. Most energy is used for indoor environment control and artificial lighting; the rest is used for the production of materials and the construction and demolition of buildings. The correct utilization of natural materials could lead to energy saving during the use of the buildings and during the phase of demolition because the less the material is subjected to transformations, the less energy cost it is. Moreover, the study of the properties of materials, in order to choose the most suitable one, allows energy saving during the building use. In particular, the utilization of local material in rural buildings minimizes the energy cost for its transport as well as its environmental impact, because, when the building is demolished, the material is reintroduced into the environmental system. In this work the principal physical and mechanical properties of the giant reed Arundo donax L. were studied and analyzed. It is a natural material available everywhere around the world and is an abundant natural resource particularly in temperate climate and subtropical areas. The giant reed has been a conventional construction material since ancient times. It was used to make baskets, building walls, fences, roofs, floors, music instruments, paper and bio-fuel. Owing to its lower thermal conductivity coefficient, it was also used in rural traditional constructions in some places. This paper proposed new technical solutions to use the giant reed in sustainable rural constructions and in the industry of eco-buildings, in particular a panel constituted by giant reed. The analysis of the theoretical thermal performances of the panel was carried out by using a heat transfer analysis software. The analysis was conducted in a steady-state situation but the situation is a simulation of the radiant and convective heat exchange within the air space of the wall. Keywords: eco-building, bio construction materials, rural buildings, Arundo Donax L.