Thermal transmittance of historical brick masonries: A comparison among standard data, analytical calculation procedures, and in situ heat flow meter measurements

The paper presents the results of an on-site survey on several historic brick masonries with different heritage values, historical ages, and internal functions. The experimental data have been compared with the results of the standard procedures normally used in Italy for assessing the thermo-physical behavior of traditional walls, in order to provide a guidance for energy audit, simulation, and labelling of historic buildings. The research methodology is based on the following steps: (i) selection of traditional building masonries; (ii) interdisciplinary assessment for materials characterization; (iii) thermal performance evaluation using different standard procedures suggested by the Italian legislation framework; (iv) comparison between the results; and (v) final performances assessment. Compared with the experimental measurements, standard and analytical procedures tend to overestimate the thermal performance of historic brick masonries. There is a correspondence between the historical ages and the λ-value of bricks. The bricks manufactured by pre-industrial techniques have lower densities than the industrial ones. This is due to the artisanship of clay, which caused the presence of sand, raw materials, and air, improving their thermal performance.