The Coop Group's administrative building on Thiersteinerallee, located in the city centre of Basel, was built in the 1970s by Gass+Boos Architekten...
COOP TH12 Headquarters
Joos Sutter
Chairman of the Coop Board of Directors
“A complete renovation of a high-rise office building in operation is like open-heart surgery.“
The energy turnaround

The Coop Group’s administrative building on Thiersteinerallee, located in the city centre of Basel, was built in the 1970s by Gass+Boos Architekten and was completely renovated in 2020. The renovation did not interrupt the administrative services and was aimed primarily at making the best possible use of the outer shell of the building preserving the exterior concrete structure. The qualities of the existing building’s interior, the column-free floor plan and well-proportioned usable areas, were retained and optimised in certain areas. By redesigning the office space, room for about a third more workplaces was created.
The facade elements between the columns in concrete were completely renewed. They now produce electricity as photovoltaic elements form the parapet cladding and emphasize the layered effect of the facade.
Well integrated into the 1,600 m2 facade of this administrative building, the 158 kWp photovoltaic system generates 69,800 kWh/yr. This covers 6% of the 1.21 GWh/yr consumed by the building itself.

The building has an open floor plan and a core housing technology and services.

 Photovoltaic elements form the parapet cladding.

The new large-sized and frameless glazing elements enhance the panoramic effect and results in bright, light-flooded rooms.

Building characteristics
  • Building typology
  • Construction type
  • Year of construction
    1978, retrofit 2020
  • Energy reference surface
    9.136 m²
  • Energy index
    175.6 kWh/m²yr (heating and electricity)
  • Energy labelling
Architect Samuel Schultze
Delegate of the board of directors of Burckhardt+Partner AG
“It was important to us to deal with the existing architecture in a sensitive and respectful way.“
Active solar surface 1.628 m²
Active solar surface ratio <50%
Peak power 158 kWp
Building skin application Cold facade
Storage Electrical battery 10kWh
Energy production
Source: Solaragentur, Schweizer Solarpreis 2021
Building skin
  • Application
  • Description
    Concrete roof insulated with 15 cm of mineral wool
  • U value
    0.15 W/m²K
  • Fastening system
  • Application
    PV cladding integrated in a cold facade
  • Description
    Concrete walls insulated with 18 cm of mineral wool.
  • U value
    0.20 W/m²K
  • Fastening system
    Megasol FAST 2 facade system

Detailed view of the PV modules on the facade of the Coop building. Source: Solaragentur.

  • Application
    Windows and skylights
  • Description
    Triple glazing with aluminum frame
  • U value
    1.0 W/m²K
  • g value

Overlooking the Güterbahnhof Wolf and the Joggeli.

The retrofit was carried out while the building remained fully occupied and functional.

BIPV module
  • Product
    Custom made
  • Manufacturer
    Megasol Energie AG
  • Cell technology
  • Front glass type/customization
    Fullblack, frameless glass/glass modules
  • Cell colour
  • Dimensions
    1185 x 1000 x 14 mm
  • Nominal power
    65 Wp
  • Specific power
    55 Wp/m²
Technical details

The aim of the new design was to create a convincing interplay between the preservation of the character-defining elements such as the exterior concrete structure, the technology and a contemporary architectural language. For these reasons, it was chosen to clad the facade elements between the columns in concrete with custom-made photovoltaic modules that completely conceal the PV technology. The modules are integrated into the facade using the MEgasol FAST 2 facade system which is fixed to the vertically laid substructure made of aluminum L profiles. Depending on the requirements, the spacing between the metal profiles of the vertical substructure is between 40 cm and 80 cm.

Hotspot image
Vertical section
Hotspot image
  • Total cost of the building
  • Price per m³  

 The photovoltaic modules blend smoothly with the concrete structure of the building.

Parties involved
  • Owner
    Coop Direktion Immobilien
  • Architect
    Burckhardt+Partner AG
  • Photovoltaic consultant
    BE Netz AG
  • Photovoltaic Installer
    Aepli Metallbau AG
  • Photo
    Burckhardt+Partner AG / Mark Niedermann
Awards and recognitions
  • Awards
    Schweizer Solarpreis 2021 (category B – buildings: renovation)
  • Publications
    Burckhardt+Partner AG Agenda 107

    Article of the 21 May 2020 on Architekturbasel.ch – Ein Markstein fürs Gundeli: Das Coop Hochhaus by Mark Niedermann