As far as I know, there are no theoretical reasons against room temperature and pressure superconductors. There is no theoretical barrier between liquid nitrogen temperature (where we have many superconductors at normal pressure) and room temperature (were we don't have, IIRC here are a few that are (not very) close, but require a high high high pressure).

not without some sort of energy being added to the system.

otherwise an ambient temperature superconductor would be a perpetual motion machine