Hygrothermal design of connections in wall systems insulated from the inside in historic building

The article presents selected issues related to raising energy standards of historical buildings. Due to their unique character, i.e. historic facades and architectural and decorative elements, the use of typical wall insulation methods, e.g. the ETICS system (External Thermal Insulation Composite Systems), is not possible. One solution is to insulate the external envelopes from the inside. Such an internal application method of insulation in the wall system has a significant impact on the profile of the occurring hygrothermal processes and it can trigger many unfavorable phenomena across the surface of the envelope. The design process and the selection of the type and thickness of insulation are carried out in accordance with commonly used criteria and principles - analogous to those used for newly designed buildings such as meeting minimum thermal insulation defined by the coefficient U and eliminating the risk of surface or interstitial condensation. In thermal insulation systems from the inside, due to the specificity of the solution (lack of the continuity of thermal insulation), special attention should be paid to the places of connections and nodes in the insulated wall systems. Due to the lack of clearly defined criteria for designing such areas and insufficiently identified nature of hygrothermal processes occurring there, the following objectives were set in the work: • identification and assessment of thermal insulation solutions within the selected 2D and 3D connections in thermal insulation systems from the inside in terms of avoiding adverse hygrothermal phenomena, • indication of problems and threats that go along with such types of thermal modernization works.