To most people when the term orchids is spoken they think of hot steamy jungles with oppressive humidity and constant rainfall. To a small extent they would be right but most orchids are found in areas that stay in temperatures between 50'-80'. To answer that question we must remember that all land is not flat.
Mountain ranges have large areas that even in the tropics manage to keep snow and ice year round.
As you come down in elevation to areas that are more temperate you encounter more and more orchids. So the answer to the dilemma here are microenvironments that exist because of elevations or the lack thereof. When you see orchids in books that say that they are cool growers, they are telling you that this plant is found at high elevations, between 2500 and 3800 meters, and may get quite hot while the sun is out on a clear day but can quickly cool off as night or cloud cover approaches, sometimes as much as 25'-30'. So in a greenhouse what you would most like to mimic is that temperature change range and not particuarily the exact temperatures. These plants more often than not will need more constant humidity and watering because of the effects of the paramo , which is a Colombian term that describes the phenomena of year round cloud cover that creates a fog bank at a certain elevation.