Thermal Transmittance Measurements of the Historical Masonries: Some Case Studies

The background shows that intervention on historical walls highlights the difficulty of identifying design solutions that are effective and compatible due to the lack of specific data on the thermal characteristics of the specific contexts investigated. This determines the choice of design solutions that are frequently inadequate and unsustainable from an environmental and economic point of view. Starting from acquired data a methodology has been developed that is based on in situ experimental investigations able to return the most probable value of transmittance of the historical walls. The values measured on the samples analysed do not reflect the literature data. For some of the samples analysed, the measured transmittance is lower than the one recorded in literature of about 10–15%. For the remaining ones, there are no reference values. The importance of an in-depth knowledge of the real behaviour of an existing historical envelope of a building is therefore fundamental, given that any evaluation mistake can have serious consequences from both an economic and environmental point of view. Underestimating the transmittance of a wall implies a waste in the use of available resources but also the disposal of greater quantities of building materials in relation to the end of life. The developed methodology can be easily replicated in other contexts and extended to all building elements that make up the historical envelope. The study will be continued by analysing further samples in order to create a reference knowledge database accessible to researchers, professionals and organizations.