Historic windows: conservation or replacement. What's the most sustainable intervention? Legislative situation, case studies and current researches

There is a definite need to improve the thermal performance of existing buildings in order to reduce carbon emissions and slow climate change. However, a sensible balance is needed when we are dealing with historic architectures. For example, as opposed to the general belief prevailing now, the replacement of windows is not necessarily an energy-saving solution, as a result of rash replacements irreplaceable values are ruined for good.That’s why the aim of this article is to collect and order recent data, to offer the results of the researches carried out in different countries to have the basis to discuss the question in a scientific and clear way and, if possible, to try to express strategies and alternative solutions in comparison with the more common type of interventions actually used. Fortunately the results of the researches in this topic confirm that the preservation and upgrading of traditional windows could be advantageous from the aspect of energy-saving and, of course, is respectful of the Built Heritage.