Hi, we have a problem with green mould appearing on the furniture in the bedroom and mould growing on things left under the bed as the door is left shut all day to prevent our 4 cats making a mess.I was wondering if it could be down to lack of air movement as it seems worst in one corner so i was wondering if putting in a closeable vent in the wall would help this as the way the house was built 1900 the air in the attic is free to come down the back of the walls too so hopefully this would create a bit of a draught.