Quantification of energy loss (a) with red (resp. black) curves representing transmission through a building atop a concrete plate (resp. a concrete plate structured with an auxetic metamaterial); Magenta curve gives the total displacement field stored inside the building above an auxetic-like metamaterial normalized with respect to the same total displacement field above the homogeneous plate. Representative out-of-plane displacement without (b1), (c1) and (d1) and with (b2), (c2) and (d2) auxetic-like metamaterial illustrate how seismic protection works at 1 Hz (b1), (b2) with the impedance mismatch between the homogeneous plate and the auxetic-like metamaterial; at 9 Hz (c1), (c2) with a local resonance; at 37 Hz (d1), (d2) with the Bragg band gap.