I grow my highlanders outside. They experience lows in the upper 30's to 40's during winter and 50's during the summer nights. Highs range from the upper 50's to low 60's in winter to 70's and occasional 80's during the day. Low 90's have happened but that is rare for me. Although highlanders don't seem to like temperatures in the 90's, they can tolerate them in short intervals provided there's ample humidity. I've had them go 4 to 5 days in the 90's in full sun without any problem. For me, it's the winter temperatures in the upper 30's combined with day temperatures in the 50's that stress my plants out the most. My Nepenthes will tolerate low temps into the 30's as long as the day can warm up a bit. Long exposure, lower light levels, and being kept too wet during this time leads to rot and that's when I lose them. 

Intermediates are easier for me to grow than lowlanders outdoors, but can also be a bit tricky. Most intermediate hybrids will tolerate my winters into the mid 40's to low 50's without damage. They do slow down until the weather warms up. It also helps if the days are warm. A warm day can offset a cold night without too much ill-effect. But in December and January when nights stay in the upper 30's to low 40's and the days in the upper 50's to low 60's my intermediates will stress. Growth ceases and leaf edges will brown. Many times the growth tip will stop growing all together. Then when spring comes the new growth tip emerges from the old one. Low temperatures in hybrids reflect the female parentage more than the male. When I see intermediate hybrids listed as intermediates, I look to see what the female parent is and that helps me determine if I can grow it on the cooler side. Intermediates make good choices for growing indoors as houseplants or "windowsill" Nepenthes. They don't need the hot humid temperatures of a lowlander or the night time temperature drops of highlanders. Many Exotica Plants intermediate hybrids make excellent choices to experiment with indoors.

When it comes to lowlanders, they just don't do well as houseplants. Some tolerate windowsills when small and will pitcher for a while. But as they get larger, they need the warm, humid temperatures for proper pitchering. Nepenthes like N. bicalcarata and N. ampullaria will hang in there when small but eventually stop pitchering and look awful. Thick leaved lowlanders like N. truncata and N. clipeata can adapt to growing as houseplants but do much better as typical lowlanders. Hybrid lowlanders where one of the parents is an intermediate could do well as an indoor Nepenthes given the other needs are met. Now I grow my lowlanders on racks covered with a clear plastic covering. I got it as an indoor greenhouse and mounted fluorescent tubes inside for light. The plants are doing well and seems a viable alternative to greenhouse or terrarium growing. Having the fluorescent fixtures inside the enclosure adds heat from the transformers that the lowlanders enjoy. They also get some sun coming through the window and that is an added bonus. It just comes down to experimentation with the lowlanders indoors. I've tried a lot of them with some success and others not so much. 

Trying to grow highlanders in typical lowland warm temperatures usually burns the plants out over time. I've heard from other growers that they can maintain some highlanders for a while, but then after a summer or two the leaves stop growing and eventually the plant dies. It's the reverse for me with lowlanders in highland conditions. Some of them will do well during the warmer months but come winter, they stop growing and sit there. They may survive one winter and come back in spring, but usually die out by the next winter. So growing your Nepenthes in their preferred temperature zone does make a difference.