Growing Orchids in Greenhouses

A real orchid aficionado that has wide collection of plants knows that they have to have a variety of temperature zones that they have to grow their plants at. And in this greenhouse range which I've had for the last few years, I grow in three temperature zones. The one greenhouse temperature zone, right now is 72 degrees and normally it's dropped to about 62 at night. In other words there is a 10 degree differential range between day and night temperatures. Adjacent to this greenhouse is the cold greenhouse which operates at a temperature range anywhere from the exterior temperature which today is in the low 50's and last year; I actually turned the heat on twice when the temperature reached 39. The other greenhouse that I have is a intermediate zone which is halfway in between both of these greenhouses. One of the things we try and do is that 10 degree differential between day and night.