You can hang your Encaustic painting next to a window or in any room with plenty of natural or artificial light, but try to avoid direct sunlight.
“Encaustic paints are perhaps the most durable form of painting, evidenced by the Faiyûm mummy portraits in Egypt, which have survived over 2000 years without cracking, flaking, or fading. Wax has several inherent qualities that allow it to withstand the test of time: it is a natural adhesive and preservative; it is moisture resistant, mildew and fungus resistant, and unappetizing to insects. Wax paint also doesn’t contain solvents or oils so they will not darken or yellow with age. Leaving the painting as fresh as the day it was painted.”