This is a criticism for pretty much all Seoul hotels. The Aventree is a modern building. Well insulated, but Koreans have a mandated heating system that is around 28-29c and thicker blankets. The AC is centrally turned off, and windows are locked or semi locked to a partial open. This makes for miserable nights trying to get a cool enough room to sleep. Unfortunately, staff can do nothing about it as it is alternately explained as “government or senior management” mandate where the fuses are disabled for energy saving in the colder months. This means Oct - April in Korea. Not just this hop, this is 3rd time in a row and same explanation. Makes sleeping during visits a difficult task.