Hemp-lime buildings: thermo-hygrometric behaviour of two case studies in North and South Italy

In the framework of Circular Economy policies aimed at reducing the consumption of raw materials, shives, an agricultural by-product of hemp cultivation, have gained a renovated life in the construction sector; new building materials, suitable for various executive techniques, have been developed exploiting the excellent thermal insulating properties of shives. When this vegetal material is mixed with a mineral binder such as lime or cement, the mixture is usually referred to as hemp-lime. In Italy, the use of hemp-lime blocks and the development of new production chains dates back only to about the last decade, while other European countries have more long-lasting experiences. In order to assess the potential benefits of hemp-lime blocks in the construction sector, it is necessary to evaluate the performance of these materials in situ, i.e. on the construction site, to obtain fundamental data to ensure that consumers and designers receive trustworthy and relevant information on products and their durability. This research work aims to be a solid base for the development of future guidelines and/or regulations at national and international level, in order to guarantee the maximum diffusion of this type of product. Then, a study plan has been carried out regarding the functionality of hemp-lime blocks in masonry, layered with finishing plaster made of fine hemp shives, to evaluate the in situ thermo-hygrometric building performance. In particular, experimental methods were developed and measurements were carried out on two structures, one in northern Italy and one in southern Italy, and precisely in Sicily, focusing the study on the performances of the walls subjected to warm Mediterranean climates.