A good quality dehumidifier has always worked for me. Cheap to run, pure water produced to use in the cars and all my equipment in the workshop/garage stays rust free.
Yes, when I had single-skin garages, especially concrete, I found a dehumidifier was an absolute must, I used to run it pretty much all the time in the winter. But with 250mm walls with cavity insulation, there's not a trace of damp and my dehumidifier has been left in the old garage.
