Energy efficiency of ground-air heat exchanger in the ventilation and airconditioning systemsRafał Łuczak, Bogusław Ptaszyński, Zbigniew Kuczera and Piotr ŻyczkowskiE3S Web Conf., 46 (2018) 00015DOI: https://doi.org/10.1051/e3sconf/20184600015