I recently received the interesting information below about dormancy from Tristan's Carnivorous Plants nursery, which is located in a tropical climate on the island of Hawaii (the "Big Island") in the state of Hawaii (USA). I don't think they would mind me using the information here.
"We live near sea level on the east side of the Big Island. Nearly all the Sarracenia do fine and go into dormancy from photoperiod on their own. They are going into it now. They will come out again in January and February and repeat their cycles. For the most part, I have seen no effect on S. flava, S. alata, S. leucophylla. In fact, it seems they all do quite well. I will say that perhaps S. purpurea will not quite attain as large of pitchers here in Hawaii as they would in cold climate with good long dormancy period, but otherwise, most seem to do just fine, which surprised me after moving here and sending many of our plants here. We had a nursery in Oregon before, so we were used to cold long dormancy periods, but we have been growing the same Sarracenias for over five years here and they seem to be doing fine."
I believe that "photoperiod" refers to the number of daylight hours. On the shortest winter day there are 11 hours from sunrise to sunset, and on the longest summer day there are 13 ½ hours of daylight. The temperature differential between winter and summer is not great. I'm guessing that in summer the highest temperature during the day is 85 degrees F., and the lowest temperature during the night is 70 degrees F. In winter, the highest day temperature is 80 degrees F., and the lowest night temperature is 60 degrees F.
So for most Sarracenia, it appears that reducing the photoperiod is more important than reducing the temperature for dormancy. I'm new to CPs, so I'd be interested to read the comments of those who have more knowledge and experience than I on this subject.