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LifeCycle Tower One Building

Highlighted Case September 2013
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The LifeCycle Tower One was built in Dornbirn (Austria) and it is the eight-story pilot project of CREE (Creative Renewable Energy & Efficiency). The building is designed to Passivhaus standards and uses prefabricated building modules that can be erected in half the time of a traditional building. The building was erected in eight days after the foundation was finished.  Wood was used as its primary structural support.  
It is the world's first hybrid wood passive house building with a modular construction system.


Project: LifeCycle Tower One Building - LCT ONE
Architect: Hermann Kaufmann ZT GmbH
Implementation: CREE Gmbh
Date: 2012/11


QUICK FACTS: Energy saving methods /Standards/Materials

Structural elements: wood-concrete composite structural system

Dimensions: 8 storeys, height 27 m, width 13 m, length 24 m

Floor space: individually rentable areas 100 m² - 1,600 m², reception area, storage areas on every floor

Façades system: modular, constructed from recycled metal, visible wooden supporting structure

Energy standard: passive house technology

Windows: triple glazing

Operating costs: optimised by automatic energy consumption monitoring system

Room conditioning: low temperature heating and high temperature cooling panels integrated in the ceiling

Air quality: ventilation system with highly efficient heat recovery, automatic control via CO2 sensors

Intelligent building service control: shutters with automatically controlled motor drive, occupancy sensors and daylight-dependent lighting control

Equipment: electronic access system, passenger lift, ethernet interconnection cabling (category 7), dispalys for detailed visualisation of energy consumption

Lighting: basic lighting of common areas, individual office lighting, automatic control

Floor construction: noise-optimised access floor system

Floor plan: individually configurable in dry construction or with system partition walls

High safety standards: automatic fire extinguishing system and fire alarm system




The LCT ONE has been primarily fitted out as an office building.  It also contains the “LifeCycle Hub” which is open to visitors as a showroom and/or museum for sustainable solutions.

LCT ONE was completed and occupied at the end of August 2012.



The LCT ONE is a Passive House Standard building.

Contributing factors of Passivhaus standards:

  • the use of  triple glass windows,
  • photovoltaic installation,
  • up to 40 cm of insulation,
  • district heating with thermal power station that is operated with wood chips,
  • LED technologies, controlled lighting, and
  • ventilation with heat recovery.


The calculated energy need for heating is about 9 kWh/(m²y) according to energy certification criteria of buildings in Austria.


A high thermal insulation level was adopted in the building envelope components; the thermal transmittance (U) values are show here:

- main external walls: U = 0,12 W/(m² K)

- roof: U = 0,07 W/(m² K)

- basement: U = 0,20 W/(m² K)

- main windows: U = 0,75 W/(m² K)


Renewable sources/Resource efficiency

Wood biomass:

  • as a natural renewable raw material;
  • unenclosed as loadbearing material in hybrid slabs, columns and façade;
  • wood floor, wall covering and ceiling 

Recyclable alum-composite metal façade


Benefits/ Results:  


  • shorter construction times
  • cost certainty
  • positive urban environmental effects - Lower noise and dust pollution during the construction phase
  • minimized sources of error in the execution of the construction work
  • flexibility - stories can be erected or dismounted at any time
  • materials - wood which can be reused into the resource cycle.  Also the wood has no chemical protection when used indoors
  • The use of serial ¨off-site production¨ enables economies of scale, consistently high building quality and speedy erection on site.


Priority is given to the use of renewable energy sources in the energy planning of the building, geothermal energy - as an example, could be used for both heating and cooling the building. The distribution and delivery system is adjusted to the respective system temperatures. Combined heating-cooling ceiling elements have been developed for space heating and cooling.

The fact that there are no load-bearing partition walls makes the system extremely flexible, allowing floor plans to be designed individually.  It is/will be possible to convert the building at any time throughout its complete life cycle.  Additionally, the LCT system components (slab, columns, façade) can be produced by many different companies, offering great opportunities for local craftsmen and the local timber industry.


Carbon footprint and lifecycle of the building

The precast structural elements require up to 50% shorter construction time compared to reinforced concrete and steel traditional structural systems.  By combining wood and concrete together, the LCT system substantially reduces the amount of concrete used in the building, resulting in a lighter structure, with a smaller foundation and up to 90% lower CO2 emissions.   The LCT system also requires 39% fewer resources, over the life of a building.  At the end of the building life, the building materials can be efficiently reused, recycled or converted into bioenergy.

It was built with prefabricated components with a modular system and meticulously designed activities.  All necessary detail solutions are pre-defined and the individual components only had to be fitted together on site. Any subsequent works with no pre-fabricated elements, such as separate fire protection cladding, were kept to a minimum.  This prevented complex details having to be done on site (correct execution is very difficult to control during construction on a normal building site).



The design is based on a 1,3 meter grid, and can be used for hotels, offices, apartments, or other needs. The façade utilizes a panelized system which can be manipulated for the client’s aesthetic preferences and supports a number of different technologies. These different technologies could include a building-integrated photovoltaic (BIPVs) system, green wall system, solar thermal panels or a second glazing curtain. Systems integration help make best use of energy resources like solar, biomass boilers and passive cooling as a result of the operable windows.

The lighting, a comfort ventilation system as well as smoke detectors and sprinklers are all integrated between the ceiling elements. Other possible elements focusing on the use of regenerative energy can also be used.  These include solar thermal systems for hot water, regenerative fuel plants where high water temperatures are required and photovoltaic systems integrated in the facade. Despite sun protection measures, the demands on room temperatures in summer (comfort criteria and workplace guidelines) make the use of passive cooling ceilings to cool the building inevitable. However, the higher energy expense that this involves can be reduced by an intelligent control concept (exterior shading controls, automatic night cooling, occupancy sensors) and correct user behaviour.

Great importance is placed on the content of recyclable material to ensure an optimum cycle of materials.


Wood-concrete slab system

A wood-concrete composite rib construction was developed for the slab. This fulfills several functions:

Firstly, it enables the floor plan to be arranged freely due to its long span (9,45 m) and secondly, it guarantees the correct separation of the storeys in the building from each other which is required by fire protection regulations.

The space between the beams is used for the technical building services that are installed flush with the slab.

Frame acoustics are improved considerable by this rib structure.

As the wood is to remain visible and to be experienced tangibly, as it is in the façade supports, no suspended ceilings have been provided for. This reduces the floor-to-floor height to a minimum, which in turn has a positive impact on investment and maintenance costs regarding energy efficiency.

In addition, the extremely low loads have an appreciably beneficial effect on the foundations of the building.



For more specific energy data please see the energy certificate included as an additional document (German).



Acronym of the case


Author(s) information


Cree GmbH


Faerbergasse 17b 6850, Dornbirn, Austria


Architecture: designed by Hermann Kaufmann

Lessons learnt

¨With our first building, the 8-storey prototype LCT ONE, we have proved that the LCT building system works. We have gained the building permission by intensive fire testing of our loadbearing system elements (hybrid slabs) and have fulfilled all fire protection requirements. We have seen that it is possible to erect an 8-storey building in just 8 days with only 5 workers (installation of our system elements – façade elements incl. windows and columns + hybrid slabs). We have also proved that it is possible to construct a high-rise building with wood as the main loadbearing material which will remain unenclosed and needs no coverage. ¨

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