in ancient roman time wood fires underneath structure heated most palace.Ancient romans used fire wood to heat walls and floor ,In so heating in Ancient time takes many turn through wood burning inside houses without  exhaust  people  constantly  fought the fumes of wood later in so proper exhausts where invented.Also to note mud filled clay on ship where used to freeze cargo.It was wet during cold nights and ships developed a sort of ice making.Also to note where the oldest fans where used and cut holes through the floor bringing up air into next room carrier later developed the air conditioner dew point humidity vapor to cool air.Wood burned in so weighs the same and when its not consumed by fire.The gas of wood weighs just as much as the wood.Also to note cloth was used during hot days the drapes where wet so cool air progressed into home.Another form of air conditioner in Older times.As so clay was used in windows to bring in cold air and cool home.Ancient air-conditioning system where far different in ancient times but in theory the same as todays.Using in itself its same principals.