Air movements and careful work affect the thermal insulation. Luftrorelser och arbetsutforande paverkar varmeisoleringsformagan.

There are two types of air movement in the shell of a building - movement along the insulation as in cavity walls and movement through the insulation. Generally the heat losses due to the faults in the inner lining of the vapour barrier and the consequential air movement through the shell are much bigger then losses due to faults in the insulation - they cannot be compensated for by using tighter wind protection.