Minimum thermal insulation or/and minimum air change. Mindestwarmeschutz oder/und mindestluftwechsel.

The current German Standard specifies a minimum thermal insulation. However even with excellent insulation, if the air change rate is too low, condensation can form. High humidity emissions in dwellings can require air change rates of more than 2/hour. The use of mechanical ventilation, possibly humidity-controlled and with a heat recovery system, is suggested to minimize ventilation heat losses. The user has to be educated to provide adequate ventilation in spring and autumn, but during the cold season the ventilation rate can be reduced to two thirds of the minimum value. Provision of an adequate air change rate must be taken into consideration when drawing up future standards on air tightness.