Energy retrofitting of the Olimpia motorway tunnel

Nowadays, the increasing deterioration of existing infrastructures requires refurbishment to guarantee service continuation in safe conditions. However, this may represent a valuable opportunity to renovate the existing heritage of infrastructures not only from a structural but also from a sustainable viewpoint. The paper illustrates the first-ever documented case of an existing tunnel section systematically converted into an energy geostructure during rehabilitation works. The geothermal piping arranged in the tunnel lining is connected using pre-insulated collectors to other heat exchanger pipes embedded in the motorway pavement. Such a geothermal system is now being tested against anti-icing and solar-collecting purposes in winter and summer, respectively. A comprehensive overview of the additional installation stages needed to energy-retrofit the existing tunnel is provided, along with a description of the adopted methodology. Then, the pressure and thermal response testing needed to verify the integrity and functionality of the system are described. Finally, the paper discloses the outcomes of the solar-collecting and anti-icing test campaigns.