Retrofit solutions for an historic building integrated with geothermal heat pumps Laura Carnieletto, Giuseppe Emmi, Marco Artuzzi, Maria Celeste Piazza, Angelo Zarrella and Michele De Carli E3S Web Conf., 111 (2019) 03055 Published online: 13 August 2019 DOI: 10.1051/e3sconf/201911103055