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This is the presentation given at the5th IBPSA Italy Conference "Building Simulation Applications" (BSA 2022), regarding the hygrothermal behaviour of the e-CLT retrofit solution developed in the Horizon 2020 Project "e-SAFE". The presentation shows that in Milan (Northern Italy), a moderate mould growth risk occurs in the wood fibre, while norisk occurs in the CLT.The liquid water (LWC) kept inside the wooden materials increases the U value by around 10% if compared with dry materials. The presentation also discusses some issues regarding the reliability of the weather data and the hogrothermal properties of CLT.

This paper advances the current knowledge on the use of prefabricated timber-based panels in building renovation by analyzing in detail the thermal performance achieved by two different renovation solutions developed in the framework of the ongoing e-SAFE H2020 project. In particular, these solutions apply to the external walls of a pilot building located in Catania (Italy) as a double-skin façade that increases also the seismic performance of the building. The dynamic energy simulations reveal that the proposed solutions allow reducing the energy need for space heating and space cooling by 66% and 25%, respectively. One further finding is that, although the proposed timber-based renovation solutions are not affected by mould growth and surface condensation risk, the impact of thermal bridges cannot be neglected after renovation. Indeed, despite the strong reduction in the magnitude of heat losses due to thermal bridges (from 667 W⋅K-1 down to 213.1 W⋅K-1), they still account for about 21% of total heat losses after the renovation. This suggests that more complex and expensive technological solutions should be introduced to further reduce heat losses in some thermal bridges, but a cost-benefit analysis should justify their adoption. Finally, overlooking these thermal bridges in dynamic energy simulations can lead to an average underestimation of the heating and cooling energy demand after the renovation, by about 16% and 5% respectively. In this regard, the paper proposes a simplified yet reliable approach to include heat transfer through thermal bridges in the post-processing stage of dynamic energy simulations under thermostatic control.

The report describes the existing state of the real pilot building, located in Catania, which will be renovated during the demonstration activities of the e-SAFE project. The document is the result of a survey activity that has concerned different aspects, including architectural issues, geometric issues, construction and energy issues, and structural issues. The results presented in this report are preliminary to the design of the renovation solutions that will be applied to the pilot building during the demonstration activity,and allowed understanding the main criticalities that must be considered during the design and the implementation stages

In G. Pernigotti, F. Patuzzi, A. Prada, V. Corrado & A. Gasparella (Eds.), Building Simulation Applications BSA 2022 (pp. 49–57).