Which air lines have to be insulated in what way?

In relation to the insulation of air lines three different circumstances must be distinguished:

1. Transport of cool air (outside and outgoing air ducts).

To prevent condensate at the outside of the piping, these must be coated by vapour diffusion-tight insulation material (such as Armaflex, perhaps also vapour permeable material covered by tear-proof, vapour-proof and perfectly taped coating). An insulation thickness of around 15 mm usually is sufficient to prevent condensation.

2. Transport of warm air through cool rooms (supply and exhaust air line).

In this case heat loss must be prevented. At the same time, the insulation must prevent condensate formation on the inner surface of the exhaust air line. Since the surroundings are cooler than the duct, there is no risk of moisture penetration into the insulation. Hence, materials non-resistant to diffusion can also be used. The thickness of insulation depends on the ambient temperature. As far as the outside temperature is concerned (uninsulated pitched roof etc.) an insulation of 50 mm is reasonable. In unheated cellars, however, insulation can be much thinner.

3. Transport of warm air in warm surroundings.

In this case insulation is actually unnecessary. If you want to e.g. plaster the line, we recommend applying a thin coating (few mm) to protect the line from potential chemical components of the plaster and for acoustic decoupling purposes. It should be constructed in way that a separation of line and plaster is effectively preserved (excessive penetration into the plaster should be avoided).

Please pay special attention to the connectors. In case of uninsulated external wall ducts the insulation according to 1. must also be installed in the cold areas of the external wall, for example.

Please also bear in mind the specifications provided in the Energy Savings Regulation.