I live on Vancouver Island, so relative humidity is very high, and depending on what source you reference, we are usually in zone 9 or 8.
I grow my orchids inside on the window sill in my room, which is positioned above the baseboard heater. I like to be warm, so usually I have the temperature at around 20°C.
Also, I generally pot my orchids with a mixture of sphagnum moss and bark (varying the proportions depending on the needs of the orchid).