Mechanical ventilation system for windows for the renovation of old buildings

Analysis and implementation of alternative ventilation systems for windows, focusing on thermal renovation of old buildings. The investigated ventilation systems were presented to an expert group. The aim was to discuss ventilation technologies with the help of different aspects and to develop a SWOT analysis.

Short Description





The thermal modernization of present buildings is a central action to attain the Austrianenergy and climate objectives. It is highly desired to increase the thermal modernization quota from 1 % to 3 % each year. In the modernization process of the building shell also the demand for an indoor ventilation rises: By using insulated walls and new windows with no thermal bridges the building becomes almost airtight and needs a fresh air supply. The air quality is sufficient but the humidity is higher than before and can lead to mildew infested rooms and a higher concentration of CO2 in the room air. These factors are affecting both the living climate and the building structure and are a risk for health.

Focused technologies

For that reason the main issues of this project are the analysis and possibilities ofimplementation of alternative window ventilation systems with focus on thermal modernization of old buildings. Window ventilation systems are decentralized ventilation components which are embedded in the window or straight connected with it. They differ into air ventilation systems with or without a fan supply.

The following technologies were involved and are available to the customers market:

  1. Aluplast GmbH - Basic Air Plus
  2. Rehau – AirComfort
  3. WinProducts „Winflip“
  4. Schüco „Vento Therm“
  5. ISY Innovation GmbH – Klimaverbundfenster
  6. Renson „AK 80“

Methodic procedure – creating of a SWOT analysis

The window ventilation systems were described and revised based on research andtechnology interviews with the manufacturers and the development teams. The focus here was to point out the technical and the custom designed criteria. In the context of a technology meeting the described and revised ventilation systems were presented to a group of experts. All experts were employees of independent scientific institutions or universities.

Aim of the technology meeting was to discuss different aspects of the ventilation technologyand work out a SWOT analysis. The intention of the SWOT analysis was to uncover the Strengths, Weaknesses, Opportunities and Threats of the different window ventilation technologies. The analysis was affected by technical and sustainable aspects.

In a second round technology meeting the detailed prepared SWOT analysis was presented to the experts from the first round and also to the manufacturers and developers of the window ventilation technology. This time the intent was to give the experts and manufacturers a moderated discussion platform and the initiation of an idea exchange process for mutual benefit. The conclusions of the second round were included into the SWOT analysis from the first round.

Furthermore the experts worked out a SWOT analysis for a central controlled ventilation system.

Conclusions and results

The research and analysis of the window ventilation systems showed that the manufacturersand developers are using very different technological approaches. Of course all systems are used for indoor venting, however when it comes to the technological implementing there are vast differences.

The window ventilation systems differs not only in the technological implementing but also inthe aimed target group and even more in the objective. Due to these aspects window ventilation systems and indoor venting systems have a different operational area.

In this context a comparison of the SWOT analysis was not needed. The window ventilation technologies and the central indoor ventilation system was checked and described by the DIN 1946-6 “Lüftung von Wohnungen – Allgemeine Anforderungen, zur Bemessung, Ausführung und Kennzeichnung, Übergabe/Übernahme (Abnahme) und Instandhaltung”.

Five out of the six mentioned systems make sure that the ventilation for moisture proofingworks accurate to DIN 1946-6 and therefore are most convenient to use for the modernization of a building. Despite an higher air tightness of the building the ventilation systems prevent the building structure from a higher air humidity, consequently from an mildew infestation and a bad influence on the residents health. All air ventilation systems are low-tech-systems with the focus on cost efficiency and a simple installation during the modernization but also as a supplementary process. A central controlled air ventilation is the most appropriate system in consideration of the energy efficiency, indoor air quality and thermal convenience. In the process of a thermal modernization the installation of such a system is often very difficult and almost impossible to realize. This is because of high investment costs and the complex implementation process into the existing building structure.

According to Greml (2004), there is still a lot of research and development work to do. Thisapplies for optimized single components and systems for supplementary installation into old buildings. This circumstance applies also for the window ventilation technologies. Accordingly within the SWOT analysis the potential for research and development in the technology was discovered.

In order to achieve a broad market penetration with window ventilation systems a marketingpush for the ventilation sector is required. It must be clear to the end-users that air is that what they need the most for living and that this is why they need a supply of it in high quality and quantity.

Project Partners

Project management

DI (FH) Alexander Gumpinger
Austrian Clean Technology

Project or cooperation partner

  • Ing. Mag.Christian Wysoudil
    ennovatis GmbH
  • KommR Dietrich Fuchs
    ISY Innovation GmbH

Contact Address

Austrian Clean Technology
Ing. Gerhard Fallent, DI (FH) Alexander Gumpinger
Guntramsdorferstraße 103, A-2340 Mödling
Tel.: +43 (2236) 8002 - 6001
Fax: +43 (2236) 8002 - 6000