Short of moving, as we can't 
Our house is a bit odd, no central heating and fairly scruffy throughout (paintwork, finish, fixtures and fittings as cheap as possible etc)
We have gas fires in every room but generally only use the one in the living room as it's all open plan with upvc windows and doors, so heats up pretty well. Never use the gas fires upstairs as worry kids will fiddle with them, also they heat up the rooms too much and it gets sweltering.
The upstairs rooms are pretty prone to mould/mildew in winter, both outside walls can't have any furniture against them or the walls and furniture start to smell musty.
We have radiator covers over both gas heaters upstairs, both painted and varnished but as they are on this outside wall they smell so much that it's all I can smell when i go in the room. No visible mould or mildew, just an ingrained musty smell.
One end of my bed was against the outside wall, mattress is fine but the wood of the bed has now caught the musty smell. Argh!
I'm struggling to think of ways to keep on top of this. The windows already need a weekly scrub to get mildew off, now this, its bloody exhausting! Not to mention unhealthy..