Concealed air conditioning is not a different technology, it is the same refrigeration circuit with the indoor half put somewhere you cannot see it. There are four normal ways to do that and they differ enormously in what they demand of the building, which is why the answer to whether a system can be hidden is always a survey answer rather than a catalogue one.
Ducted behind a ceiling
The most complete concealment: the unit lives in a void and only linear or circular grilles are visible. It needs the void, the access and the plan, and where those exist it is the neatest result available. Where they do not, forming a bulkhead to create them is a joinery and plastering job on top of the mechanical one.
Ceiling air conditioner cassettes
A cassette sits within the ceiling void with only its face visible, throwing air in two or four directions. It needs much less depth than full ductwork and gives even distribution in a square room, which is why it is the standard answer in offices. In a domestic room it is a visible square on the ceiling rather than a box on the wall, which many owners prefer.
Integrated air conditioning built into joinery
A high wall head can be enclosed in a bespoke cabinet or bulkhead with a grille, provided the enclosure gives the manufacturer's clearances and the filter can still be reached. Get either wrong and the unit either starves or becomes unserviceable, so the joiner needs the installation manual before they draw anything.
Floor and low wall units
Low level consoles sit like a radiator under a window and suit rooms with full height glazing or sloping ceilings where nothing can be mounted high. They are visible but they read as heating rather than as air conditioning, which for many owners is the point. The pipe run is also easier where the floor void is accessible.
Questions people ask about concealed air conditioning
Does hidden air conditioning perform worse?
It can, and always for the same reason: airflow. Every indoor unit has stated clearances for intake and discharge, and any enclosure that narrows them makes the fan work harder for less air. Concealment done to the manufacturer's clearances costs nothing in performance; concealment done to taste alone usually does.
Can the outdoor unit be hidden too?
It can be screened, not enclosed. It needs a generous free volume of air around it and a clear discharge path, so a slatted screen with real gaps and the specified clearance is fine and a sealed box is not. Enclosing a condenser is how a system ends up cutting out on the hottest day of the year.
Is a cassette suitable for a bedroom?
Often yes, and the thing to check is the throw pattern against where the bed is. A four way cassette in the middle of a small bedroom ceiling can put air directly onto the occupants, which is exactly the complaint people are trying to avoid by choosing it.
Which concealed option is cheapest?
A cassette, generally, where a suitable void already exists, because it avoids both ductwork and joinery. A ducted system is the most expensive and the most complete. Built in joinery sits between them and its cost is mostly the cabinetmaker's rather than the engineer's.