Practice in the Field of Thermal Retrofitting in Historic Buildings and Preservation of the Authentic Tissue of Façades of Historic Buildings in Poland

Abstract

The pursuit to reduce emissions of harmful substances to the atmosphere resulting from the combustion of fuels for heating purposes makes a building more ecological and environmentally friendly. All operations aimed to limit emissions of pollutants into the atmosphere are motivated by the growing environmental awareness of developed societies and alarming reports on the global warming and its effects. In Poland, legal regulations are the answer to this problem. According to them, it is necessary to reduce the limit values of the heat transfer coefficient for partitions in rebuilt buildings. These values will be successively tightened until 1 January 2021. The compliance with the limits of the heat transfer coefficient is also required for historic buildings. For obvious reasons, historical buildings do not meet the technical requirements imposed on modern architectural structures. The constructional technique of partitions in historic buildings and building materials used in them require to undertake additional actions to provide thermal extra insulation of such buildings. The provision of extra insulation of historic buildings so that they can meet the assumed technical requirements is a challenge for designers and manufacturers of materials used for extra insulation in buildings. The first part of the paper covers the influence of modern thermal retrofitting methods and techniques applied in historic buildings conducted under the provisions of law onto the preservation of authenticity of the historical tissue of monuments. The paper analyses a variety of traditional and most recent methods and materials used in the provision of thermal insulation of external vertical partitions in historic wooden and brick-based buildings with wooden and masonry structures. Then the second part of the paper based on the conducted analyses determines the effectiveness of the adopted thermal retrofitting techniques, threats resulting from the applied methods towards the authenticity of historic building structures. At the same time, a set of factors which are relevant to the preservation of the authentic character of historic buildings was specified. To sum up, on the grounds of the conducted research studies it was indicated that the thermal retrofitting methods applied currently in historic buildings based on the provision of extra insulation for vertical partitions (applied from the inside of buildings) in reversible techniques do not admittedly devastate the authentic structure of walls but still do not ensure the expected and required technical parameters (and in the case of wooden architecture they lead even to accelerated degradation). The effective thermal retrofitting methods involving external extra insulation of partitions damage the authentic tissue of monuments. As a result of stricter legal regulations and a lack of good thermal retrofitting methods, it may be necessary to decommission historic buildings from their use.