Topics: Construction of individual buildings, Heating, ventilation and cooling, Heating & cooling networks, Operational management & energy management, Heat from soil, groundwater and sewage, Methodologically sound economic analyses, Monitoring & balancing, Optimisation of operations
Innovation: The financing model enables an energy-optimised building to be achieved despite tight public coffers. A borehole heat exchanger array is used in winter for preheating the supply air and in summer as a source of cooling energy for concrete core temperature


  • Construction project realised as a private public partnership (PPP)
  • Borehole heat exchanger array supports passive air conditioning via concrete core activation
  • Solar and glare protection with daylight control in the glazing cavity
  • Presence- and brightness-controlled lighting concept
  • The total primary energy consumption is 82 kWh/m² p.a. in accordance with DIN 18599

A special financing model was used for delivering the project: a public private partnership or PPP for short. Despite a tight public budget, the client (the Region of Hanover) has succeeded in constructing a consistently energy-optimised building for 300 staff. The building is air-conditioned using concrete core activation of the office ceiling slabs. The necessary cooling in summer is provided by 12 borehole heat exchangers that are also used in winter to pre-heat the supply air. The lighting concept includes presence- and brightness-controlled lighting and automatically controlled solar shading.

Project context

The new Regionshaus building in Hanover (Germany) represents the first time that a building which complies with the standards of the support initiative "Energy-Optimised Construction" (EnOB) has been realised with the PPP financing model. The Region of Hanover is constructing the building in Hanover's city centre. The strict energy standard was contractually defined as an objective within the PPP project, and comprises planning, construction, and financing over 20 years. The accompanying scientific research is sponsored by the German Federal Ministry of Economics and Technology (BMWi) as an EnOB project, and received subsidies from proKlima ("the enercity fund").

Research focus

This building demonstrates two important aspects of innovative construction: firstly, the contractor's requirements with regard to energy efficiency and occupant comfort are set very high, and secondly a particular financing model is applied: the "public private partnership", or PPP for short. The contractor (the Region of Hanover), despite a tight public budget, is able to build a consistently energy-optimised building for 300 staff.


Building concept

The PPP invitation to tender defined the essential objectives with regard to energy efficiency, but allowed the planners considerable freedom of design.

The design which is now in implementation provides a high-tech energy concept, which answers the region's call for a reliable low-maintenance building with low life cycle costs.

This building, in Hanover's inner city, adds to the Region of Hanover's large number of administration buildings. The 5-storey angular building structure provides the region with a new attractive location, with a spacious, glazed, multifunctional hall on the ground floor protruding towards the street.

The particular challenge of this model project is the accommodation of the EnOB standard's strict energy efficiency requirements in an open competition run by a public authority. The primary energy requirement for heating, ventilation, cooling and lighting must not exceed 100 kWh/m2 per annum.

Energy concept

The energy concept encompasses the essential aspects of achieving high energy efficiency: a compact building structure (A/V = 0.3), good thermal insulation (walls with 160 mm of mineral fibre in thermal conductivity group 035), good windows (U = 1.2 W/(m2K)), and good air-tightness (n50 < 1.5).

The rooms are heated by means of static radiators, and can be cooled in summer with concrete core activation. Ventilation systems with highly efficient heat recovery and moisture recovery are provided for the multipurpose hall and the sanitary rooms. The building is supplied with remote heating. Cooling occurs via an array of 12 borehole heat exchangers, each 70 m in length. A chiller is provided only as a reserve. The heat exchangers are also used in winter to preheat the outdoor air in the hall's ventilation system. Thus, additional cooling of the heat exchangers takes place in winter, so in the following summer a greater cooling potential is available. The building is equipped with building control technology, as well as a comprehensive measurement concept, and can be monitored online.


Information on this subject will become available as the project continue.

Optimisation measures and possibilities

Information on this subject will become available as the project continue.

Construction costs and profitability

The planning process is subject to the legal framework for assessing profitability: construction is only permitted if the construction costs in the PPP process do not exceed the cost estimates. Thus, the EnOB standard is achieved with a cost guarantee!

Project data

Building data

Building owner Region Hannover, Haus der Regionen, 30169 Hannover
Investor CommerzLeasing und Immobilien AG
Building type Non-residential building in massive reinforced concrete structure
Year of construction 2007
Start of planning 2004
Completion 03.2007
Inauguration 04.2007
Gross floor area 8.441 m²
Heated net floor area 7.134 m²
Gross volume 28.911 m³
Work places 300 Personen
Usable floor area (according to EnEV) 5.399 m²
Main usable floor area 3.599 m²
A/V ratio 0,30 m²/m³

Energy data

Energy demand  
Energy indices according to German regulation EnEV (in kWh/m2a)  
Heating energy demand 34,80 kWh/m²a
Primary energy district heating 46,00 kWh/m²a
Overall primary energy requirement 93,00 kWh/m²a
Measured energy consumption data  
Net construction costs (according to German DIN 276) relating to gross floor area (BGF, according to German DIN 277)  
Primary energy district heating 2008 30,8 kWh/m²a
Total source energy 2008 82,1 kWh/m²a

Implementation costs

Net construction costs (according to German DIN 276) relating to gross floor area (BGF, according to German DIN 277)  
Construction (KG 300) 762 EUR/m²
Technical system (KG 400) 282 EUR/m²
These figures represent established costs  

Last Update: 26. December 2013

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