I have found that Ren. imschootiana does fine outside for me. Also Ren. citrina . Vanda tricolor, V. cristata, V. roeblingiana, V. coerulea (somewhat, can be touchy) and some other Vandaceous genera. Of course, Neof. (Vanda) falcata and any of its hybrids with other Vandaceous genera. All of these need a little shading, but are cold-tolerant.