Assessment of the actual hygrothermal performance of glass mineralwool insulation applied 25 years ago in masonry cavity walls

An experimental study was carried out on buildings constructed in the 1980s adopting vertical envelopeswith a glass wool insulation layer in the cavity. The aims of this study are to evaluate the insulationconservation state after 25 years, to assess the actual indoor thermal comfort and to compare differentretrofit interventions.The research included the following phases: laboratory tests on insulation samples to quantify anychanges of morphological, chemical, physical and thermal proprieties of the material; detailed on-sitemonitoring in order to analyze the thermal comfort conditions; dynamic thermal simulations to assess theimpact of different retrofit scenarios to satisfy the limits imposed by the current energy saving standard.The results show that the glass fibers and the binder were affected by a degradation process thusincreasing both water absorption and thermal conductivity; thermal comfort and consumptions were notinfluenced by the insulation aging; the most effective retrofit is the introduction of an external insulationlayer.