Nearly zero energy renovation concepts for apartment buildings Kalle Kuusk, Jens Naumann, Annina Gritzki, Clemens Felsmann, Michele De Carli, Massimo Tonon and Jarek Kurnitski E3S Web Conf., 172 (2020) 18009 Published online: 30 June 2020 DOI: 10.1051/e3sconf/202017218009