Numerical investigation of the energy flexibility of different heating and cooling systemsEvangelia Loukou, Mingzhe Liu, Hicham Johra, Per Heiselberg, Bianca A. Dia and Rógvi K. D. ClementsenE3S Web Conf., 111 (2019) 06001DOI: https://doi.org/10.1051/e3sconf/201911106001