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GreenBuilding Partner WWFF - ENERGYbase

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On the 6th of June 2007 the foundation stone for one of the most innovative energy projects in Austria has been laid. Under the auspieces of the Vienna Economic Development Fund (WWFF), the ENERGYbase project consists of the construction of a passive house in the 21st district of Vienna. Its development relies on 3 main pillars, namely energy efficiency, user comfort and the utilization of renewable energies. All energy applications are concerned: heating, cooling, hot water, lighting, auxiliary power at minimum energy requirements. The expected final energy consumption of the building could reach the exceptional value of 20 kWh/m². One of the main aspects of the project is that the entire architecture and design are oriented towards the optimal use of renewable energy. An harmonious balance between esthetical and functional features has for example been reached with the louvered facade design, which consists of a series of shading and glass panels combined with thermal collectors and photovoltaic cells. The orientation of these panels enables to optain an optimal daylight yield, good passive solar gains, excellent summer shading and efficient production of heat and power by means of collectors and PV systems.

The office building ENERGYbase has been erected 2007 by the WWFF Business and Service Center GmbH. The building has 10,690 m² of gross floor area and hosts besides offices also laboratories and a university of applied sciences. Due to the exceptional shape of the facade and a wide range of other measures the heating demand of the building (3.87 kWh/m³y) is 72% below the Austrian Building code.

The following measures did contribute to reaching this figure:

Building envelope:

  • External walls - 26 cm insulation, 0.22 W/m²K
  • Roof - 0.13 W/m²K
  • Basement - 0.18 W/m²K
  • Passive house windows - 0.75 W/m²K
  • Optimisation of the building envelope (insulation, airthightness, windows, cold bridges)
  • Partly wood construction

Building services:

  • Geothermal energy: for heating and cooling
  • Mechanical ventilation with heat recovery and integration of plants for humidification
  • Cooling: free cooling, solar cooling (innovative solar sorption system, which is being applied in Austria to this extent for the first time)
  • Active and passive use of solar energy: solar thermal system (300 m²), PV system (400 m²), the shape of the south facade allows the passive use of solar energy (direct solar radiation into the building during the winter)

Other measures:

  • Energy efficient lighting: the layout and the south facade concept make it possible to supply the entire building with daylight. Additionally special light directing blinds also channel daylight into the depths of the rooms.
  • Use of sustainable building material
  • Humidification with the so-called green buffer zones: four-storey high buffer rooms contain 500 Cyperus Grass type plants specially bred for humidification purposes. They function as closed moisture generating system which can be integrated as adjustable, precisely controlled and calculabel units into building engineering systems.
  • Detailed monitoring of energy consumption, etc. within scientific projects
  • Integrated planning process and use of simulation tools

Acronym of the case

Office ENERGYbase

Lessons learnt

Due to the wide range of measures the ENERGYbase has a 80% lower final energy demand than other buildings. The ENERGYbase uses 25 kWh/m²y of electricity for heating, cooling, ventilation, lighting and others. About 19% are produced by the PV system installed. The remaining 20 kWh/m²y are taken from the net. Normal office buildings need about 15 kWh/m²y only for lighting.

Award labels

Additional documents

Available link languages

Source of funding

Funding description

The ENERGYbase was subject of research in various scientific projects.


See also case 'ENERGY base'