<b>Air-Conditioning and Ventilation Systems</b> Regardless of the type of ship, the air conditioning and ventilation conditions on ships have a significant influence on the well-being of the crew and passengers as well as the trouble-free operation of machines, systems and facilities. Air conditioning systems create the necessary environmental conditions in ships for climate-friendly technical systems and ensure a pleasant room climate for the people on board, which is usually given at a temperature of around 20-22 °C and a relative humidity of 40-50%. Free ventilation - natural ventilation - is only used in exceptional cases on small ships. Usually the air supply and disposal takes place today as overpressure ventilation by means of ventilation systems. For this purpose, the supply air is pumped into the areas to be ventilated (especially the engine room, cargo holds on ferries) using electric motor fans. The exhaust air is directed outside via exhaust chimneys, flaps or blinds. In the case of ventilation and air conditioning systems, the supply air (outside air / circulating air) must be cleaned using state-of-the-art air filters before it is fed into the areas to be ventilated in accordance with the requirements regarding the use of the rooms. The ventilation and air conditioning system itself must not become a source of danger (e.g. through hazardous substances, bacteria, mold or noise). The above-mentioned required room air conditions (temperature, humidity, purity and CO2 content) are created on the ship with air conditioning systems. They have the task of bringing the air in a room into a certain state and keeping it (“conditioning”). Since external air conditions and corrosive sea air are to be expected in ship air conditioning, these systems must meet the highest quality standards. Here, a large shipyard has to focus on the material day-to-day requirements with regard to corrosion behavior. Metallic parts are therefore often powder-coated or made of stainless steel. In the area of ocean shipping, the stated indoor air values must therefore always reliably guarantee well-being over a wide climate range.