I've found Nepenthes rafflesianas to be very adaptable plants. Although their growth is definitely more lush and "juicy" in a hot and humid environment, they can be grown in less than optimal conditions and do just fine. Below are examples of the same clone growing in different conditions. The only thing that is that same is the photo-period under the lights. Both plants are quite healthy, and there is only one inch of difference in the size of the pitchers.
Example 1: This one is growing in a lowland plant case with consistent high humidity, and a daily rise to 90º from nighttime low temperatures of 75-80º each day. This pitcher opened recently, and is 8.5" from the bottom to the top of the lid. The plant is an established cutting from the plant in the second example.
Example 2: This one is growing out in the open in the basement with low humidity. Temperatures rise to about 70º each day from nighttime lows in the low 60s. These temperatures have been consistent since October. The pitcher is older than the one in the lowland case, and is 7.5" from the bottom to the top of the pitcher. I do mist the plant well once each night. (I have found that all the plants I have growing in an open situation seem to appreciate a good misting at night.)