Fan ventilation


We let windows breathe

Comfortable protection against moisture with heat recovery more
  • Needs-oriented ventilation with no intervention from the user as per DIN 1946-6
  • Heat supply efficiency up to 86%
  • Compact design (485x240x98mm)
  • Profile-neutral and usable with all materials (timber, PVC, aluminium)
  • Installed in windows with or without shutters
  • Wall structures in old or new buildings with installation depth of 240 mm or higher
  • Window profile depth up to 102 mm

The new compact VENTRA® window fan lets windows breathe and therefore ensures a permanent supply of fresh air for living spaces when windows are closed. This means of protecting against damp via user-independent ventilation prevents mould formation and safeguards occupants well-being. The high level of heat recovery is a defining feature of VENTRA®. The heat exchanger saves energy and ensures a comfortable inlet air temperature. This is an easy means of ventilating and saving energy costs. Integrated in the window reveal, the VENTRA® is almost invisible from inside and outside. The occupants dont hear it because it works whisper-quietly. Straightforward installation and easy operation at the press of a button go without saying. VENTRA® install with the window for immediate ventilation and well-being.

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Yes. There are different KFW energy standards according to which you can build or refurbish a house. This standard stipulates how much thermal heat and how much primary energy a house is allowed to consume. This classification also specifies the maximum transmission heat losses. As the ventilation system is a factor in this calculation, it is hard to say which KFW standard the VENTRA allows you to satisfy.

A conclusive answer to this question would have to be given in the form of a calculation of the window's overall noise reduction value that includes the noise reduction value of the fan.

LN stands for Level of Noise, indicating the standard sound pressure level. dB(A) is a measure of sound pressure level (according to curve A) that has been weighted in an effort to account for the relative loudness perceived by the human ear. The LN value measured in dB(A) allows for a comparison of different devices as all measurements taken are founded on the same basis.

G3: Coarse dust filters for particles > 10μm. These filters are grouped into classes 1 through 4, with the degree of efficiency increasing with higher numbers.

M5: Fine dust filters for particle sizes between 1 and 10 μm. These filters are categorised in classes M5, M6 as well as F7 to F9, with the degree of efficiency increasing with higher numbers.

No, not directly. There are, however, general incentive programmes that try to encourage renovations designed to improve energy efficiency and that are sponsored, for example, by the KfW or local communities.

Yes. This value ranges between 30 dB and 35 dB.

The VENTRA® does not have any effect when built into regular windows.
As part of soundproof windows:
Noise reduction value Dn, e, w in dB:

Level 1: 41

Level 2: 41

Level 3: 39

Off and with the dampers closed: 52

Condensation runs off from the heat exchanger to the opening in the VENTRA® and into the air guiding profile. It cannot accumulate inside the VENTRA® itself.

Since the air will not exit until it has passed the roller shutters and is expelled with a slight swirl towards the exterior, the risk of the roller shutters freezing up is negligible.

You will find that the ice on the window sill forms only in the area behind the roller shutters as the water will first drain towards the outside before turning to ice on account of the slope in the window sill.

Level 1: 8 m³/h, approx. 3.8 W

Level 2: 15 m³/h, approx. 8.2 W

Level ¾: 30 m³/h, 34.5 W

Calculated across all operating levels and based on an operating time of 24 hours throughout 365 days a year and an electricity rate of 27ct/kWh:

Level 1: 33 kWh; 8.91 €

Level 2: 72 kWh; 19.44 €

Level 3: 302 kWh; 81.54 €

Inherent noise LN in dB(A)

Level 1: 26 dB

Level 2: 37 dB

Level ¾: 62 dB

The dimensions of the VENTRA® are 485x240x98 mm.

Slide dampers can be used to close the VENTRA® in adverse weather conditions. They are controlled from the interior panel.

Yes. We do recommend, however, to leave it on level 1 (moisture protection level) at all times.

No, but no insect will enter the ducts for as long as the fan is running.

No. The VENTRA® is a moisture protection fan. The design of a passive house requires, however, that all people inside the house enjoy the same air quality without the need to open the window. To satisfy this prerequisite, the VENTRA® would have to constantly operate at maximum capacity.

Approx. 250 mm. This height is also specified in the installation instructions.

Yes. In this case, the VENTRA® is installed at the height of the handle. Installation in window door elements requires the use of the 3000mm air guiding profile that is designed especially for this purpose.

Yes, in combination with standard roller shutter guides with a width of up to 50 mm. We have designed a special L-shaped air guiding profile that encases the roller shutter guide, shifting the position of the openings to the outside of the closed roller shutters.

We do not recommend this option as the VENTRA® needs to be installed along with an air guiding profile. Another difficulty is to chip away the brickwork around the window to expose the frame.

We do not recommend this option as the VENTRA® needs to be installed along with an air guiding profile. Another difficulty is to chip away the brickwork around the window to expose the frame.

The VENTRA® can be used if these appliances are operated independently of the air in the room, which means that the air supplied to these appliances must not be extracted from the ambient air.
Operating the VENTRA® simultaneously with fireplaces and ventilation systems that are dependent on the air available in the room is prohibited.

The powerful vacuum generated may cause the VENTRA®, especially when operating at its lower settings, to also allow air to flow through the exhaust duct and into the room. This does, however, not pose a problem. The VENTRA® will, in this case, operate as a pressure equalisation system.

This depends on the volume of space. A volume flow of approx. 8 m³/h is sufficient to protect a room with a surface area of 14 m² and a ceiling height of 2.5 m against moisture. Operating level 1 would be sufficient in this case.

There is no real bottom limit. The VENTRA® will cut off automatically when the normal frost protection strategy (no freezing up of the heat exchanger until temperatures reach -12°C) is no longer sufficient.

It will come back on automatically as soon as the temperature rises again.

No. Its circuit board is not protected against the moisture and chlorine vapours commonly occurring at swimming pools. In addition, the use of local ventilation equipment is inadvisable on account of the vast volumes of air necessary to ventilate swimming pools.

There is an inspection opening through which all individual components can be replaced. To change components, the user needs to remove the panel. The inspection opening is located behind the panel.

The VENTRA® is equipped with two filters. One is located on the supply side, i.e. the outside air is filtered before it is sent through the heat exchanger. The second filter is found in the volume flow of the exhaust air flowing out of the room, i.e. the exhausted interior air is filtered before it passes through the heat exchanger.

We recommend that you change the filter at least once a year. The replacement intervals do, however, also depend on the environmental conditions and the operating time at the different operating levels.

You need to remove the panel before you can replace the filter. Located behind the panel is the inspection opening through which the filter can be replaced.

Yes. A necessary filter change is indicated by a red LED.

End customers can buy the filters from the same dealers who sell the VENTRA®.

Yes. The heat exchanger can be removed through the inspection opening and cleaned under running water.

The instruction manual recommends to check the heat exchanger for contamination and, if necessary, clean it during a filter change.

Click on the following link to watch the VENTRA film in German and English:

Catalogue window automation 2020
(51,2 MB)


We let windows breathe.

Airing correctly

Do you know what to do? We have a few tips for you.

Modern and renovated buildings meet strict energy-saving requirements and are well insulated and extremely air-tight. Windows are also air-tight today, preventing wind and precipitation from penetrating the building envelope and conserving costly heat energy. Things were different in the past. Leaks and poorer heat insulation properties in glazing and frames let in fresh air unintentionally on a continuous basis, ventilating homes incidentally. In winter, warm air would also leak out where fresh air entered. This wasted energy and drove up heating costs.

Residential buildings now feature increasingly air-tight building envelopes with air-tight windows, doors and façades, whether an energy-saving building or energy-renovated existing building. Energy performance of buildings directives and guidelines stipulate ventilation with no intervention from the user to protect occupant health and the building fabric. In times of demographic change and variations in family structures, many people work all day long and are not able to ventilate rooms as needed.

Such people require a reliable, energy-saving solution for ventilating each room as desired with no intervention from the user in compliance with DIN 1946-6 requirements. Windows and French doors in new buildings can been provided with integrated window fans to meet these requirements. They reliably provide self-regulating ventilation and are effective in preventing any moisture damage when occupants are absent for longer periods of time. A new window can be retrofit to the window fans. Discreetly mounted in the window reveal, they provide permanent, stress-free ventilation for buildings and apartments fully automatically.

Ventilating correctly prevents moisture and mould growth

Around 7 to 11 litres of water are emitted into indoor air on a daily basis in a three-person household. This humidity needs to be removed through ventilation. If it is not, mould damage will occur as a consequence of inadequate air exchange.

Showers are taken in the mornings, the coffee machine is switched on and a T-shirt may be quickly washed while the coffee is being made and hung up to dry before occupants set off for work. It's then time to leave home. Windows and doors are locked. The humidity lingers in the rooms. Only controllable ventilation can take on the task of moving the air around in a "regulated" fashion with optimised energy use, replacing the air to some extent.

It is quite simple to ventilate correctly: If the air is stale and someone has just finished cooking or showering, then the stale and possibly very moist air needs to be replaced with fresh, dry air. Replacing air is healthy, promotes hygienic conditions and prevents moisture damage and pathogenic mould growth. This is referred to as controlled, needs-based ventilation.

The new compact VENTRA® window fan lets windows breathe, providing a permanent fresh air supply to living spaces when windows are closed. The VENTRA® window fan is a reliable, energy-saving solution for ventilating each room as desired with no intervention from the user in compliance with DIN 1946-6 requirements. This fan is particularly suitable for rooms where a great deal of moist air occurs, such as kitchens, bathrooms and bedrooms. The possibility of providing protection against moisture prevents mould and ensures well-being and a healthy indoor climate.

Mould top toxic substance in homes

Building experts consider mould to be the top toxic substance in homes, alongside plasticisers, preservers and formaldehyde. About 30% of all homes are estimated to be affected. Moisture particularly occurs in modern and energy-renovated buildings since the required effective insulation also affects air exchange. Electronic air exchange systems help to improve the indoor climate and prevent mould growth


What types of building is a decentralised window fan suitable for?
New builds/old buildings/renovations

Electricity and heating energy account for a large percentage of household expenses. Home owners and occupants want to use energy efficiently to cut costs. However, optimum ventilation of apartments and houses is essential to remain healthy and maintain quality in living spaces. Both sets of requirements are very easily met with the VENTRA® window fan.

KfW subsidy for installation of the VENTRA® window fan
it is possible to apply for a loan or subsidy to install the VENTRA® window fan from the German development bank KfW Bank. This is because installing mechanical ventilation systems such as the VENTRA® window fan is considered eligible for a subsidy according to the guidelines on subsidising investment measures in existing buildings to help advance energy efficiency refurbishment in such building stock. Building owners can choose between a loan at a favourable interest rate or an investment grant as part of the bank's "Energy-Efficient Refurbishment" programme. The subsidy is ten percent of the refurbishment costs with 5,000 euros being the maximum per housing unit. A ventilation design concept needs to be produced if a third or more of windows or roof surfaces are replaced. This may then mean that a ventilation system needs to be installed.
The aim is to increase energy efficiency.

More information on subsidies:

Interesting links & addresses
You will find interesting links and useful addresses which provide comprehensive information on home ventilation:


German Window + Façade Association (VFF)
Produces regular video clips which give a short, concise presentation on key topics concerning windows, front doors and conservatories for end users:

Ventilating correctly

Ventilating correctly with Frank (Dec. 2015; in German)

Federal Old Building Renovation Working Group NPO, Berlin (BAKA)
Provides information on the topic, especially old buildings and renovations:

European Testing Center for Domestic Ventilation Systems (TZWL) NPO
TZWL provides services for building owners, architects, planners and the industry relating to energy efficiency, air quality and environmental technologies. TZWL produces independent ventilation design concepts as per DIN 1946-6 and conducts blower door tests.

You'll find the website here

Construction industry trade magazine:


On the importance of air exchange (10-2015; in German)        Article in PDF format