In japanese, the word of 温暖室 doesn't exist. At least.i haven't heard in my twenty years life.you may want to say 温室(おんしつ）. it means green house in english.温室 is the room to nurture plant.and 温室 is often build on land surface. but,室(むろ）　is made underground. and it's purpose is mainly conservation and drying something.