Air conditioning in a hotel is by no means something obvious, far from it. It is not a simple air conditioning unit to be applied to the wall, although in Italy it would seem trivial, considering our beautiful climate and the practical absence of skyscrapers, and perhaps it is. But in the world where God has been less lenient with the distribution of good climate and population density, air conditioning in hotels is a very, very serious matter. The air quality of hotels is such an important thing that it gave rise to the need for a real institution, complete with protocols, certifications and specialized personnel. There is even a world ranking that classifies which hotel chain is the best looking, complete with the second and third place winner of the Hotel AIR AWARDS. This year the Holiday Inn chain won for the quality of the air, a result achieved thanks to technological systems, ionizing filters, etc. It is true, as mentioned before, that in Italy opening the window is not only feasible, but certainly better, but if you are “away from home”, but very “away from home”, with temperatures over 40°C, humidity over 90%, pollution, absurd polar temperatures… or we are on the 40th or 60th floor, where it is not only forbidden to open a window for safety reasons, but the hotels are completely hermetic and live without any opening to the outside, with only air conditioning, you realize that the air quality is a really serious matter. Normally large motors are placed on the roof or at the end of the corridor on each floor, and suck and blow air through two large rectangular pipes inside the false ceiling of the corridor. They blow the air through the grids placed on the veil inside the room where the false ceiling ends and suck from the bathroom. The bathroom is thus always found in depression, so much that the bathroom door must be cut in the lower part or grilled to the point of letting a huge amount of air pass from the room to enter the bathroom, and then exit through the ducting. This process, among other things, keeps the room always free of bathroom odors. Of course, in Italy we can use the usual unit hanging on the wall, connected to the open window sensor and to the stand-by of the room, with a centralized controlled temperature that respects the energy class.