I do run a heater in winter to keep the minimum temp in the glasshouse to about 12C. *That seems to be enough to keep the lowlanders happy, though growth is very slow.
Myself and another member of this forum both grow Neps outside here in Melbourne. *I have both Sanguinea and Ventricosa doing just fine even through winter. *Christian has Khasiana, Vent, Maxima, hydrids of and a few other things, all doing very well.