TO BUILD WITH STRAW: A SUSTAINABLE FUTURE

Build with straw bale, today, is an innovative way of building, ensuring a high living comfort, in line with sustainability. The first straw buildings are much older than we image. Nowadays, a recurring topic is looking to the past to find a better future. As Arthur Pinero Ala writes: “I believe that the future is the past that it goes inside from another entrance”. The memory has many answers, sometimes with many contradictions. Reflect on the story’s lesson means rediscovering and reinterpreting to make greater awareness. Subject of research and experimentation is the straw. Straw presents may capacities. Different features have been recognized in the bales. One is that it has a good level of stress resistance. They have performed laboratory tests with a wall made by straw bales (3,6 m long; 2,4 height). The resistance to breakage was about equal 48.000kg/mq, for bales positioned flat, otherwise it was about equal 13.500 kg/mq, for bales positioned length. Furthermore, straw has good resistance to the forces of the earthquake. In fact, straw is flexible, strong, ductile and lightweight, with a good width-to-height ratio and it becomes ideal for earthquake resistant construction, making sure that the connections between foundations and roofs are properly implemented. Shortly after the earthquake, the straw bale comes back to the initial configuration. Straw has a good fire resistance, as the Italian said flash in the pan. This said exhales the behavior of the straw exposed to fire. As a matter of fact, it emits a lot of smoke (that it has a low content of CO2) because straw does not burn as it’s a dry plant and then died. A wall resists up to 90 minutes with fire to 1000 °C. Straw has good thermal proprieties too because it’s packaged with very large thicknesses. A straw bale positioned flat has a transmittance value of about 0.13 W/mqK. The straw’s spread is favoured because straw is waste material, abundance, cheap and zero kilometre material, added value for sustainability. It has no cost of transformation because the switch from waste material to construction raw material is immediate. The use of straw in construction requires a low technological level and it allows to activate self-constructing and "do-it-yourself" processes. The construction of the building is very fast compared to a traditional concrete construction. Last but not least, a straw bale construction results in a saving of 10/15 %. This saving continues over time with energy savings too. As discussed above, the use of straw offers several advantages, however, contrasted with an attitude of widespread scepticism towards a "poor" technology. Its poor diffusion can compromise its economy. However, the evaluations made are an incentive for dissemination, especially in the place where this way of building belongs to tradition. belonging to the places is an added value to sustainability. The use of past techniques, today, one of the thinnest logic of innovation that looks to the past, with the awareness of the potential of current techniques and mechanisms that govern behaviors