Buildings are always affected by humidity. Especially buildings, which can not be calculated regarding the building fabric, the usage, the humidity load, the temperature or the outdoor climate, have higher requirements for a protection. A good humidity protection is more necessary than in former times: The wheather changes harder and faster. It brings a bigger humidity load. It is necessary to distinguish the origins of humidity or water and to know, which measure or technique has which effect to the relevant origin. It is necessary to operate depending on the types of rooms: Historic or modern, not-sealed or sealed, thermally insulated or not. An earth-touched room needs a different protection than a not-earth-touched one, a heated room a different one than a non-heated one. It is good to recognize errors or not-complete presumes. Sometimes the impermeability of a building is helpful, but sometimes it should be permeable for air and its humidity. Controlling and regulating the humidity bring the protection for the buildings. The relevant knowledge of the humidity physics, the extended knowledge, the experiences and the requirements of the building have to be considered. Modern electronic controller and sensor systems can be able to recognize the requirements and to do the protection, when they have the suitable hardware and software with the knowledge and the requirements. Quite as heating regulators do the regulating of a temperature of a room, the climate controller will do the regulating of the climate and the humidity. Competent detection by suitable sensors, a controller system with a very godd competence in physics and an adequate concept are able to regulate the humidity in a way, that all kind of rooms are protected during all statuses and processes, at different humidity loads and changing terms, during the usage and during the changes by the wheather, by day and night and by the seasons.