Timber Passive House at Mühlweg, 1210 Vienna

Low-rise housing with 70 units (200 residents) in solid wood plate construction designed to meet European passive building standards. Strategies for highly ecological and sustainable building within the economic constraints of social housing, Mühlweg, 1210 Vienna. Industrial pre-fabrication, ...

Short Description





In March 2004, BAI Bauträger Austria Immobilien GmbH won the competition for housing developers in the field of timber and mix-timber construction awarded by wohnfonds_wien. KLEA Wohnbau Gesellschaft m.b.H. was established by BAI to realise this rental building by the end of 2006 using subsidised loan by the State of Vienna.

The project concept was based on:

  • Multi-storey municipally subsidised rental housing with 70 units (around 200 inhabitants),
  • Massive timber construction (according to the Viennese building regulations),
  • Standards for passive-houses (according to the guidelines of the Magistrate department 25, Vienna),
  • Project strategy based on utmost ecological and long-term sustainability within the limit of total construction costs set for residential buildings using subsidy funds.

With the cooperation of the programme "Subsidy for Demonstration Projects" within the framework of the programme "Building of tomorrow" additional and innovative qualities, materials, and methods could be realised as described in detail as below:

Modules of subsidy

  • Industrially produced prefabrication of wood-construction including facade,
  • Vacuum insulation (trial application),
  • Passive-house wood/aluminium window,
  • Heating / (ventilation), airflow noise protection,
  • Quality control, market diffusion, evaluation of users' satisfaction.


BAI pursued the strategy to develop a residential building typology based on ecological and long-term sustainability as a demonstration project and consequently to establish it in the market-financed residential building market.


  • Floor space around 6.750 m² (included 490 m2 loggia)
  • Residential units 70 (included SOS-Kinderdorf units and start-up flats)
  • Underground parking 70 parking spaces
  • Construction costs around € 7.200.000,-
  • Total investment costs around € 11.000.000,-
  • Start of construction October 2005
  • Completion and handing-over November 2006

Project's Results

Tender / Awarding

The tendered costs were considerably above the construction costs set by the competition and the cost estimate, both in terms of general contractor "master builder, building services included" and general contractor "Timber construction, facade included". As a consequence the project was analyzed based on tendered costs as well as based on predicted results of further negotiations on potential savings and finally realised based on the following provisions:

Provisions (under the conditions, that the qualities as defined in the competition were preserved)

  • Reduction of the constructed volume of the basement and underground parking,
  • Simplification of the structural design and/or construction method of the work of the master builder,
  • Simplified timber construction,
  • Omission of earth collector due to low level of efficiency at high construction and maintenance costs,
  • Individually room-controlled heating system as small radiators instead of (mini-) floor heating,
  • Centrally controlled ventilation system instead of locally controlled,
  • Omission of rainwater cisterns due to operation and hygiene reasons at enormous costs.

Qualities requested

  • Mix timber construction: massive timber construction, utmost industrially produced prefabrication,
  • Standards for passive-house: individually room-controlled temperature, increased airflow noise protection,
  • Ecological concept: passive construction method, use of solar energy, massive timber construction, optimization of utilities costs,
  • High quality architecture and landscape.

Modules of subsidy

  • Industrially produced prefabrication of wood-construction included façade
    Realised by KLH Massivholz GmbH in cooperation with Kulmer Holz-Leimbau GesmbH.
  • Vacuum insulation
    Trial application (at house's entrance).
  • Passive-house wood/aluminium windows
    Originally planed pivot windows could not be used since no PH-capability in combination with the high requirements of sound insulation set by the Viennese building regulation could be verified.
    By order of KLH Massivholz GmbH windows of the company Stefan (passive-house window system Variotherm) were taken under consideration.
  • Heating / (ventilation), room acoustics
    Individually room-controlled (additional) heating system by small radiators,
    Additional arrangements to reduce airflow noise protection.
  • Quality control in planning, realisation and operation, evaluation of construction
    Consulting for passive-house- and timber-construction, increased internal activities of BAI.
  • Market diffusion, evaluation of users' satisfaction
    Remarkable interests also at international level and positive echoes in all areas, first evaluation report on users' satisfaction, increased internal activities of BAI.


The rather ambitious goals set by the project development in general as well as the additional provisions foreseen by the modules of subsidy could be realised to a great extent. From the current perspective - subject to the short operation time - it can be said, that the project has been a great success.

Already during the project development a close cooperation with KLH Massivholz GmbH was established. Without such engagement - also from the involved authorities, planners and builder - at present it would not be possible to realize such a project and/or comparable projects at competitive construction costs. Therefore such projects should be still considered as demonstration projects and analyzed from this point of view.

Project Images

Terms of use: The pictures listed underneath the header “Project Pictures” originate from the projects in the frame of the programmes City of Tomorrow, Building of Tomorrow and the IEA Research Cooperation. They may be used credited for non-commercial purposes under the Creative Commons License Attribution-NonCommercial (CC BY-NC).

Project Partners

Project management

DI Georg Kogler
BAI Bauträger Austria Immobilien GmbH

Project or cooperation partner

  • KLH Massivholz GmbH
  • Dietrich I Untertrifaller Architekten
  • JR-Consult ZT GmbH
  • IBO Österreichisches Institut für Baubiologie und -ökologie
  • Holzforschung Austria
  • Schöberl & Pöll OEG
  • Dr. Alexander Keul, Angewandte Psychologie

Contact Address

BAI Bauträger Austria Immobilien GmbH
DI Georg Kogler
A-1020 Wien, Leopold-Moses-Gasse 4
Telefon: +43 1 33146-4529
Telefax: +43 1 33146-4241
E-Mail: georg.kogler@bai.at