Functional principle

Ventilation is essential

Ventilation is the cornerstone of a comfortable and energy-efficient indoor climate and for maintaining your health. This applies to both domestic ventilation and ventilation in buildings used for commercial purposes.

With Zehnder Comfosystems ventilation units, the air volume can be simply adjusted to suit requirements. This comfortable ventilation guarantees a pleasant and healthy indoor climate at all times.

How ventilation works


  • Constantly fresh air
  • Saves energy through heat recovery
  • Retains property value by preventing mildew formation
  • Promotes good health
  • Protects against outside noise
  • Government-subsidised

How heat recovery works

Equipped with patented cross-counter flow heat exchangers as standard, Zehnder ventilation units can transfer the heat energy of the stale extract air to the fresh air.

This thermal transfer takes place via thin plastic plates using the cross-flow principle.

Heat recovery of up to 95% is possible, representing an energy saving of up to 50%.

Hans-Peter Zehnder

Humidity recovery

Due to the enthalpy exchanger up to 65% of moisture in the extract air can be recovered.

This enables the relative air humidity in the building to be optimised, which is ideal for excessively dry air in winter. During this process, steam is diffused through the membrane. The moisture and heat recovered are transferred to the fresh supply air, with no transfer of odour or microbes.

In addition, the Zehnder enthalpy exchanger is very easy to clean with just water and a mild cleaning agent.

Hans-Peter Zehnder

Most Zehnder ventilation units are equipped with a 100% summer by-pass.

It has the task of bypassing the extract air at the heat exchanger. This prevents the supply air that has been pre-cooled by the sub-soil heat exchanger in summer from being heated by the warm extract air.

A function that can also be used on cooler summer nights.

Hans-Peter Zehnder