The retrofit of the facade and the interiors was carried out while the building remained fully occupied and functional, thus enabling the...
Hanwha Headquarters
Architect Ben van Berkel - UNStudio
``By means of a reductive, integrated gesture, the facade design for the Hanwha HQ implements fully inclusive systems which significantly impact the interior climate of the building, improve user comfort and ensure high levels of sustainability and affordability. Through fully integrated design strategies today’s facades can provide responsive and performative envelopes that both contextually and conceptually react to their local surroundings, whilst simultaneously determining interior conditions.”
Remodelling “in place”

The retrofit of the facade and the interiors was carried out while the building remained fully occupied and functional, thus enabling the company to remain working in the building throughout the construction period. In order to enable this, three floors were refurbished at a time, on both the interior and the facade.
Electing to choose a construction method that would have minimal impact on both the operation of the company and on the environment, it serves as a good example for all stakeholders in the construction process to consider alternative parameters and sustainable measures that can be introduced when retrofitting existing buildings.

80% of the overall facade is made up of a limited set of base modules.

The remaining twenty percent consist of modules with minor variations of the base modules.

The intricate panelling and window system, arranged in a seemingly random geometric pattern, has been designed to best take advantage of the regular daily movements of the sun (estimated amount of sunlight abt. 4-5hours).

The existing facade of flat, dark glass was replaced with clear glass panels and photovoltaic modules. After the retrofit it was possible to reduce the energy consumption by about 40%. The PV installation covers approximately the lighting on 4 floors a day. The average daily energy consumption in this building is approximately 20,000 kWh.

Building characteristics
  • Building typology
  • Construction type
  • Year of construction
    1998, retrofit 2016 – 2019
  • Gross floor area
    57,696 m²
  • Energy index
    242.4 kWh/m²y
  • Energy labelling
    G-SEED (total score: 88.2)
Architect Astrid Piber - UNStudio
``We strongly believe in integrated solutions. Of course you could treat technology as a simple add-on but then it will never be as effective as it could be.``
Active solar surface  n/a  275 m²
Active solar surface ratio  n/a  <25%
Peak power  61 kWp  73 kWp
Building skin application  Flat roof  Cold facade
Storage NO
Energy production
Source: UNStudio
Measurements in progress
Building skin
  • Application
    Flat roof
  • Description
    Standard PV modules are laid on a metallic support system.
  • U value
  • Fastening system
  • Other
  • Application
    PV cladding integrated in the cold facade
  • Description
    The unglazed surfaces of the southern facades are outfitted with photovoltaic modules. The opaque portions are finished with a 150mm of insulating layer and a 3mm aluminium back pane.
  • U value
    0.25 W/m²K
  • Fastening system
  • Other
    Light-Density Open-Cell Spray Foam (ocSPF) was used to insulate the opaque portions of the facades.

The upper part of the elements used on the south facade is angled so as to receive direct sunlight.

  • Application
    Glazed facades
  • Description
    Insulated glass in aluminum framing covers about half of the building surface.
  • U value
    1.06 W/m²K
  • g value
  • Other

The facade is designed so the windows are angled away from direct sunlight, to stop heat gain and glare.

The basis for the facade expression is to achieve an effect of variety, irregularity and intricacy throughout.

BIPV module
  • Manufacturer
    Hanwha Q CELLS GmbH
  • Cell technology
  • Front glass type/customization
    3.2 mm thermally pre-stressed glass with anti-reflection technology.
  • Cell Colour
  • Dimensions
    1348 x 1000 mm
  • Nominal power
    225 Wp
  • Specific power
    168 Wp/m²
  • Weight
    15.5 Kg
  • Specific weight
    11.5 Kg/m²
Technical details

Direct solar impact on the building is reduced by shading which is provided by angling the glazing away from direct sunlight, while the upper portion of the south facade is angled to receive direct sunlight.

PV cells were placed on the opaque panels on the south / southeast facade at the open zones where there is an optimal amount of direct sunlight. Furthermore, PV modules are angled in the areas of the facade where energy from the sun can best be harvested.

Electric wiring is connected from the PV modules through each floor’s ceiling to an underground electrical room.

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  • Total cost of the building
  • Cubic meter price

The retrofit of the office tower incorporates the remodelling of the facade, the interior of the common spaces, lobbies, meeting levels, auditorium and executive areas, along with the redesign of the landscaping.

Parties involved
  • Owner
    Hanwha Group
  • Architect
  • Local consultant and executive architect
    Gansam Architects & Partners
  • Landscape consultant and designer
    Loos van Vliet, Haarlem
  • Facade and sustainability consultant
    ARUP Hong Kong
  • Lighting consultant interior and facade 
    AG Licht, Cologne
  • Photo
Awards and recognitions
  • Awards
    CTBUH Awards 2020 – Renovation Award 2020 Award of Excellence
  • Green Building Award 2014, Finalist
  • Publications
    Tall + Urban Innovation 2020: Dominant Trends – Mar 2020 – CTBUH Journal 2020 Issue II
  • High-Rises From the Past and For the Future – Oct 2019 – 2019 Chicago 10th World Congress Proceedings – 50 Forward | 50 Back