Another thing to remember is the humidity levels. During this period, dendrobiums do not need a lot of moisture. Very little water will be enough to keep their roots alive. Also keep in mind that their roots constantly need plenty of air circulation so you should place them where there is a lot of fresh air.
Remember, that is based on energy usage, not comfort-levels, which are the purpose of having an air conditioner, in my not-so-humble opinion. Fact: At night, the ideal temperature comfort range for Americans drops to 65 to 72 degrees Fahrenheit (or about 87 degrees if you are my wife).
I had it set at 70 on the second floor because I work on the third floor and I would like it cooler up there. I took a reading of the temperature coming out of the vents yesterday and the temperature of the air was 72 degrees. My downstairs air conditioner blows out air that is about 65 degrees.