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GreenBuilding Partner Amt der NÖ Landesregierung - Business Center Lower Austria

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The aim of the building owner, the province of Lower Austria, was to erect a sustainable energy efficient building that serves as a model for other building owners. The site consists of four building parts that are connected by a parking deck and not conditioned crossings. The concept of the architects Gschwantner and Millbacher in combination with the HVAC system follows the rules of passive house technology. Measurements include: thermal optimized building envelope (very good insulation, moderate glazed area, high air tightness, avoiding of thermal bridges), mechanical ventilation system for the hygienic air change, heating and cooling with activation of thermal masses and the use of renewable energy (ground water heat pump). Special aspects of the building are the use of natural light through light regulating sun blends, massive reduction of air pollutant emissions because of chemical management and one part of the building was erected as a carrying wooden structure.

The Business Center Lower Austria has been built in 2007 and has a gross floor area of approximately 7000 m². The heating and cooling demand are 66.5 respectively 90% lower than the Lower Austrian Building code. The heating demand is 4.57 kWh/m³y and the cooling demand is 0.1 kWh/m³y. The calculated final energy demand is 77 kWh/m²y.

The following measures have been implemented to reach these figures:

Building envelope:

  • External walls - 35 cm insulation, 0.15 W/m²K
  • Roof - 0.12 W/m²K
  • Basement - 0.14 W/m²K
  • Passive house windows - 0.91 W/m²K
  • Optimisation of the building envelope (insulation, airthightness, windows, cold bridges)

Building services:

  • Ground water heat pump for heating and cooling using the ground water influenced by the nearby river Traisen
  • Activation of thermal masses
  • Mechanical ventilation with heat recovery

Other measures:

  • Use of daylight
  • External, mechanical shading
  • Regulation of lighting
  • Energy efficient lighting
  • Use of sustainable building materials and chemical management results in high indoor air quality
  • Detailed monitoring of energy consumption

This building was the first low energy building the Province of Lower Austria invested in and will be a role model for further building projects.

Acronym of the case

Business Center Lower Austria

Lessons learnt

Measured energy consumption: The cooling demand is very low due to some simple measures like a moderate share of windows in combination with external shading. This results in a high summer comfort without additional energy costs for cooling. Findings from facility management: Thermal simulations for sensitive parts of the building have been absolutly necessary. A longer adjustment period is also necessary (therefore also longer warranty periods). Slight technical building services without capacity buffer for planning and implementation mistakes means that there are higher requirements for planning and implementation and a lower buffer for the case that the internal loads do not correspond to the planned ones.

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