Costruzioni in legno e paglia. Valutazioni energetiche ed economiche

The construction department is an overriding sector in terms of energy and material consumption as well as CO2 emissions and waste production. In order to pursue a sustainable renewal of this branch a new approach is strongly needed, both for the interventions on new buildings and existing ones. It requires awareness and starts from the materials' selection process. It is well known that a large part of the impact of our buildings comes from the process, use, and disposal of materials. Thus, nowadays materials must be recyclable, renewable, locally available (to minimize transport cost and emissions), and with low environmental impact. Lately, the interest in natural materials has increased considerably. These materials can be newly-developed or belong to the tradition. In the latter case, mistrust of the common opinion may be an impediment to the re-evaluation of materials, and more effort is required to reintroduce them into the market. This paper presents the economical and environmental evaluation of a building system made by using natural materials. In particular, the load-bearing structure is in wood, whereas straw is used as an infill. The study compares this natural system with the common one used for residential purposes in Italy, which is characterized by a load-bearing structure in reinforced concrete and infills in porous brick. To obtain reliable results any external factors to the inner traits of the two systems were excluded, thus the comparison was launched between two identical buildings in terms of geometry, internal spaces distribution, orientations, climate, and contour conditions. The results of the analyses and simulations carried out, testify that the natural building system in wood and straw can be a valid alternative to the “traditional” one, both in economical and energetical terms.