Found in DT comments:
"One more thing I have to post here: Good isulation gets you into another serious problem: If a house is naturally dump (dumpness coming from the ground up) a good isulation will definetely cause you enourmous MOULD FORMATION. To such an extend, that you will have to air and ventilate the rooms in cold winter (or use a de-humidifier) - or it will ruin your health!!!"
Looks like someone has let harry out again..