Balanced Office Building

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The balanced office building

The Balanced Office Building (BOB) is an office building in Aachen that has been optimized for energy efficiency and sustainability .

The building was erected in 2002 in the Laurensberg district of the Aachen solar estate and has been intensively measured and funded since then as part of the solar construction program of the Federal Ministry of Economics .

The design comes from the architects Hahn Helten, the energy and sustainability concept was developed by the VIKA engineering company, the structural engineering was carried out by the engineering company Burkhard Walter. All three of which are builders at the same time.

The Balanced Office Building in Aachen has become a prototype for an office building series that was started in 2013.


The Balanced Office Building relies exclusively on near-surface heating and cooling using geothermal energy . The small flow temperatures are distributed in the building by means of concrete core activation . This simultaneously leads to high efficiency and a pleasant level of comfort. Radiant cold, in particular, is considered more comfortable than appropriate ventilation technology. The hygienic exchange of air is promoted into the building by means of a mechanical ventilation system and, while the fresh air quality is always constant, ensures energy efficiency through heat recovery in winter and cold recovery in summer.

A LON -based building management system controls and regulates the building concept, such as the daylight-dependent lighting control. Building functions and energy efficiency are monitored via an intranet. Around 1.7 million measurement data are recorded every year.

The control algorithm was further optimized based on the measured values. In the meantime, concrete core activation is only regulated by means of temperature balance and no longer by room air temperature. If the ceiling is in equilibrium with its surroundings, the system stops and does not consume any energy. If heat is given off, it is heated, it is absorbed, it is cooled.

Construction engineering

Triple glazing with a very low degree of energy transmission was also chosen for the building envelope . An internal blind with daylight control function ensures that the glare protection required for computer workstations is inexpensively combined with the function of light control on the ceiling. This means that the room can be illuminated with daylight even in summer while the blinds are being lowered.

The office is designed as a combination office, so that single, double and open-plan offices can be combined as required. The interior is designed as a freely configurable loft. For example, the interior walls do not contain any technology.

Energy efficiency

The Federal Ministry of Economics launched the solar construction project (today EnOB) and intensively measured 25 office buildings. BOB has achieved the following primary energy value here (primary energy factor 1.8 as of 2016):

  • Heating energy = 15 kWh / m²a
  • Cooling = 3 kWh / m²a
  • Ventilation = 12 kWh / m²a
  • Lighting = 18 kWh / m²a
  • Hot water = 0.6 kWh / m²a
  • Total = 48.6 kWh / m²a

For the final energy (= energy costs) this means 27 kWh / m²a.


  • 2002 Monitoring funding from the Federal Ministry of Economics and Technology,
  • 2002 move into the building
  • 2003 BDA Aachen Architecture Prize
  • 2005 5th and, for the time being, last optimized control algorithm is installed
  • 2006 BOB has the lowest energy costs in the context of the solar construction project
  • 2007 BINE Info appears on BOB
  • 2010 First prize won in the context of the International Energy Storage Concrete Innovation Award, awarded by the Beton Handels- und Werbegesellschaft mbH Vienna, Austria Beton Handels- und Werbegesellschaft Austria
  • 2013 Foundation of BOB efficiency design AG
  • 2015 Awarded by KlimaExpo NRW as a pioneer for climate protection

Individual evidence

  1. a b Sustainable office building as an overall concept

Web links

Coordinates: 50 ° 47 ′ 41.4 ″  N , 6 ° 3 ′ 30 ″  E