Rich literature explores materials and construction techniques of historic buildings, but limited information is available about the thermal and hygrometric features of their envelope. Nevertheless, accurate hygrothermal data are essential for identifying effective energy upgrade measures, which must be compatible with the conservation of the architectural heritage. In order to fill this gap, it is necessary to refer to local contexts, where the variety of historic buildings is limited and their material and construction features are comparable. This paper focuses on historic masonry walls and discusses the results of twenty in-situ measurements of thermal conductance, performed along two years in Palermo according to the international standard ISO 9869. The tests were performed in a monumental building, characterized by an interesting variety of calcarenite stone walls, which are typical of the local historic architecture. The aim is developing a knowledge framework and collecting thermal data specific to the architectural heritage of Palermo, which is relevant for its variety and extent. For this purpose, the measurement results have been compared with thermal conductance calculated according to the standard EN ISO 6946. Calculations were based on different thermal conductivity values, appropriate for calcarenite stones and provided by existing data collections. The findings show that calculations are in good agreement with measurements if the thermal conductivity of tuff from UNI 10351 is assumed for calcarenite. Conversely, the value provided by UNI EN ISO 10456 for light sedimentary rocks induces to overestimate substantially the thermal conductance of calcarenite stone walls. (C) 2018 Elsevier B.V. All rights reserved.