Performance Assessment of Thermal Bridges in the Connecting Regions Between Existing Buildings and External Steel Dissipative Structures

About 40% of global energy consumption is attributed to the construction sector which, in view of the European Green Deal, needs a profound renewal in structural, energy, and environmental performance. Exoskeletons offer structural retrofit solutions that allow an overall architectural and performance upgrade to the building but must be supported by energy analyzes of each technological component involved to be considered really efficient. The adoption of exoskeletons can determine thermal criticalities on the envelope and in particular, at a local level, thermal bridges in the connections between pre-existing and new structures. This paper deals with this topic by referring to a real explanatory case and reports some early results of an assessment based on a 2D thermal bridge finite element model under steady-state conditions. The results point out the likelihood of vapor condensation inside components of the building envelope and an increase of the linear transmittance Ψ through thermal bridges.