Office Building WKS - Plus Energy Office Building in Ernstbrunn

The new office building (headquarter) of Windkraft Simonsfeld AG in Ernstbrunn (Lower Austria) is planned as a plus energy building. From this excellent starting conditions it is intended to make seven more steps to explore innovative options for energy plus buildings.

Short Description




Contents and Objectives

The seven steps are:

  1. direct mechanical use of wind power (wind pressure)
  2. direct use of direct current generated on-site
  3. ecological optimisation of building and traffic from and to the building using energy generated on-site
  4. space efficiency of building surface for generating thermal solar energy and photo­voltaic power
  5. a façade optimised for passive solar gains and excellent natural lighting in winter and high gains of thermal and photovoltaic energy in summer („100 % energy façade“)
  6. Environmental friendly transport to the building site using the railway adjacent to the building site
  7. optimised demand respond electricity management: a „smart house“ to support (fu­ture) „smart grids“.

Some costs for innovative building features applied for in the original research grant applica­tion have been cut (e.g. use of DC power) or cancelled. Other innovative building elements have been built in an improved version or have been newly developed, contributing to the concept (e.g. PV, thermal collectors, glass façade, ventilation elements).


  • Research
  • Building physics – building simulation
  • LCA analysis
  • TQB Building Certification
  • Architectural design and HVAC planning
  • Shading studies
  • Measurements of indoor air quality and energy consumption


Use of wind pressure: Based on thermal building simulation the potential of natural cross ventilation for the winter garden by a) wind turbine on the roof and b) passive openings in the façade has been designed and tested. The wind turbines also support mechanically the controlled ventilation. A low-speed motor has been devised, ordered, and installed to use groundwater for cooling of the host computers. Indoor air quality ans energy consumption is being monitored in the building.

Direct Current Appliances: Market research revealed DC appliances to be unavail­able and DC-DC-converters for supplying several low-voltage devices to be inefficient. How­ever a promising option of using DC charging stations for electric vehicles has been identi­fied.  The built battery store has been evaluated continually but proved to be economically not feasible due to lacking subsidy schemes.

Ecological expenditure including traffic: scenarios for transportation have been de­veloped to a stage in which involvement of the staff may be considered for further advance­ment.

Space efficiency of on-site energy production: Less groundwater was found than was expected. This caused a shift to geothermal heating anc cooling. Solar thermal collector area was reduced accordingly. PV solar energy area has been extended to account for the optimum with regard to subsidy regulation. The planned wind turbine fan has been relo­cated as not to impair the PV facilities and prevent condensation. Coverage arrangement of PV elements at the façade has been compacted.

Energy optimisation of building construction: costs of concrete vs. wooden floors have been compared. With thermal building simulation the impact of thermal mass on ther­mal comfort and energy consumption has been established and optimised. Use of plants for humidification has been planned.  Thermal quality of glazing has been improved. Integration of a thermal collector has been studied.

Environmentally friendly rail transport to the building site has been investigated. Fi­nally it was decided against this option. One reason was, that the selected supplier has no rail connection.

Support for Smart Grids: use of accumulators from the wind farm were considered and a separate battery room has been planned to make provision for maximised use of self-produced electricity in future eco­nomically more favourable conditions.

Monitoring, TQB building certification and building costs: A TQB pre-certificate has been issued, a monitoring concept has been devised, and devices for evaluation and optim­isation of building services have been installed. With monitoring some HVAC problems could be identified. The building was certified with ÖGNB and with klimaaktiv (Gold level).

Prospects / Suggestions for future research

The new office building (headquarter) of Windkraft Simonsfeld AG in Ernstbrunn, Lower Aus­tria, has been planned as a Plus Energy Building. From these already excellent starting condi­tions 7 more innovative steps have been implemented to achieve an energy gaining build­ing. The building will produce 50 5 more energy than it requires, thereby surpassing plus energy criteria of Haus der Zukunft. PV can be and will be increased to twice the area.

The office building was completed and became operative in May 2014. Until November 2014 some failures were remedied. In May 2014 the monitoring program has been started.

The project was awarded Gold in the klimaaktiv certification and reached 965 out of 1000 points. The project was also TQB-certified and reached 942 out of 1000 points.

Project Partners

Contact Address

Windkraft Simonsfeld AG
Mayer Florian
Simonsfeld 57a, 2115 Ernstbrunn
Tel.: +43 (680) 3304157