It’s a simple fact of physics that hot air rises and cool air sinks.
Heating & ACs take this into account. For example, ductless mini-split ACs should be located high up on the wall in a section of the home where the equipment will not be blocked by furniture to allow for unplugged air flow. Also, it helps to install the outdoor part of an AC on either the north or south wall of your beach home to shield it from the sun. Even having a nearby tree to offer shade can be helpful, although you do not necessarily want to have debris falling from the tree onto the condenser unit. You generally also want to keep the condenser equipment unplugged by anything in the yard. Keeping physics in mind, one of the most efficient means of heating a beach home comes in the form of radiant heated floors. Radiant heated floors consist of tubes under the flooring of your beach home that are heated either by electricity or hot water. Because the heat source is below the floorboards it will naturally emanate upwards, thereby efficiently heating your beach home as opposed to a forced air Heating & Air Conditioning system with vents on the ceiling. Unless you’re 10 ft tall you generally won’t appreciate the heat hanging up there so it’s best to use radiant heated floors, although they can be quite fancy. In summary, the fact that hot air rises and cool air descends is taken into account when it comes to the design of particular heating & a/cs systems.