Evaluation of mechanical class room ventilation systems in Austria and generation of a planning guideline
Due to the requirements of a learner-friendly approach (i.e. satisfactory indoor air quality) as well as energy savings in kindergartens and schools mechanical classroom ventilation systems (with heat recovery) are essential in today's educational environment. Numerous studies have shown that schools with ventilation via windows have bad indoor air quality. It is beyond doubt that healthy and fresh air represents a major prerequisite for a successful learning process. However, in Austria research in this field is still at its beginning and relevant experience has neither been sufficiently documented nor can be used adequately for future projects.
The most important final aim of this project relating to the aims of the program "Building of Tomorrow" is to collect positive solutions, mistakes and shortcomings. Based on experiences during the evaluation process a planning guideline and quality criteria for the future implementation of classroom ventilation systems in new buildings or the renovation of already existing buildings are developed in order to improve the quality and to support the distribution of classroom ventilation systems.
The evaluation consists of two main parts: the evaluation of mechanical classroom ventilation systems - divided into an analysis of acceptance and the technical analysis - and the development of a planning guideline as well as detailed quality criteria.
This evaluation was based on the previously developed "Austrian map of current classroom ventilation systems" as well as the collection and analysis of already existing individual studies. 16 schools were selected from the data base of schools with mechanical classroom ventilation systems and took part in the evaluation process. The project not only focused on technical aspects, but also concentrated on the collection of data and the presentation of the analysis of acceptance among present users (pupils, teachers, janitors). Therefore the evaluation consists of the analysis of acceptance and a technical evaluation.
Analysis of acceptance: For the analysis of acceptance two written questionnaires were developed: one for pupils, teachers and janitors and one for architects, planners and building owners.
Technical evaluation: The technical evaluation especially focuses on the following aspects: the choice of ventilation concept (decentral, semi-central, central), air mass and air distribution, the loss of pressure, the type of heat recovery, the electrical energy need, the type of anti-freezing protection, the type of post heating to comfort temperature, the indoor air quality achieved (carbon dioxide, humidity, VOC), necessary repairs and maintenance costs as well as the current noise load.
Planning guideline: A planning guideline and 61 detailed quality criteria for classroom ventilation systems were developed based on the results of existing planning directives, drafts of norms and norms as well as the results of the analysis of acceptance and the technical evaluation.
Project homepage: www.komfortlüftung.at
An overview of the most important results:
- Austrian map of current classroom ventilation systems: The database contained 59 schools with classroom ventilation systems (Dec. 2007).
- Overview of studies in the field of classroom ventilation systems: Numerous studies in Germany, Switzerland and Austria dealing with indoor air quality show that ventilation via windows does not achieve learner-friendly indoor air quality. It was clearly proven that insufficient indoor air quality which is typical for classrooms without mechanical ventilation systems leads to a significant decrease in performance.
- Analysis of acceptance: The analysis of acceptance illustrated the necessity of an intense communication strategy with teachers and pupils in order to minimize misunderstandings and to achieve an ideal use of the ventilation system. A lack of information and communication leads to problems of acceptance and to unsuitable reactions and unsatisfied users especially in cases of failure in the implementation phase.
- Technical evaluation: So far building owners, architects and planners of ventilation systems have not been very familiar with classroom ventilation systems and thus feel insecure in this field. A significant potential for improvement in the choice of systems, the necessary air mass, the air guidance (use of cascades) and controlling strategies has been noticed.
- Planning guideline - 61 quality criteria for classroom ventilation systems: The planning guideline consists of three parts:
- Checklist for basis data collection
- Guidelines and recommendations
- 61 Quality criteria
New or renovated school buildings without mechanical ventilation systems including heat recovery do not fulfill the requirements of today's modern building standards. It is also recommended to install humidity recovery systems. Studies in Austria, Germany and Switzerland clearly showed that ventilation via windows does not lead to satisfactory indoor air quality. On the one hand, the partly unsatisfactory quality of ventilation systems implemented so far is due to the planners‘ lack of experience and on the other hand, it is due to insufficient specifications made by clients. However, numerous excellent examples show that satisfactory classroom ventilation systems can be installed without considerable effort and at moderate costs. With the aid of the 61 quality criteria for classroom ventilation systems clients can sufficiently specify the quality of the systems. The planning guideline enhances the collection of relevant information and supports the planners in their conceptual phases. Taking the increased learning benefit into consideration mechanical ventilation systems also lead to a financial benefit. The need for and the "value" of the high quality building support is evident in the context of mechanical classroom ventilation systems.
DI Andreas Greml
Project or cooperation partner
- TB Andreas Greml, DI Ernst Blümel, DI (FH) Arnold Gössler
- DI Roland Kapferer
- Ing. Wolfgang Leitzinger
- Mag. Juergen Suschek-Berger
Interuniversitäres Forschungszentrum Graz
- DI Peter Tappler
IBO/Department für Bauen und Umwelt/Donauuniversität Krems