The simplest and cheapest way is to install a dehumidifier, which quite simply dries the damp air in the crawl space. Many people try to reduce the humidity by increasing the ventilation in the crawl space, in the belief that they are replacing the damp air with fresh air.
As we explained above, the moisture actually comes into the cellar largely with the outdoor air, which is why increased ventilation actually increases the humidity and thereby the problem. The result is therefore that the growth of mould can be accelerated. The installation of a dehumidifier is relatively simple, but requires a good deal of knowledge and experience, which is why we strongly recommend that you employ a specialist.
Each cellar is unique, which means that the installation will be designed a little differently in each individual case.