The house is not built well, with think walls and stupid storage heaters rather than any proper heating system. We don't have a de-humidifier, but put out several humidity-aborbing boxes (basically a plastic tub with vents at the top and a thick layer of silica crystals inside) and they quickly filled up with water some some humidity was removed. I may have to look into a de-humidifier soon (ironic as when I lived in Illinois I had a humidifier to deal with the incredibly dry air in winter!) Air circulation doesn't seem to help. Even my bike, stored in a draughty shed with plenty of circulation was covered in mould after the winter. and the biggest patches of mould are around droughty doors and windows which will have plenty of circulation. Plan is a deep-clean week-end once the weather permits hanging things outside to dry, but the mould always seems to come back despite the use of bleach. The cleaning only gets stuff off the surface and the mould is still there under the layer of paint and plaster on the walls. BF who grew up in this part of the world just thinks mould is part of the deal when you live here but I am determined to attack it if there is any way! I'll check those links out later when I next need a break from work....there must be some way of keeping even a badly built house somewhat healthy!