The Wattbuck residential development in Effretikon is typical example of the architectural style of the 1960s and 1970s. For some of the high-rise buildings...
Wattbuck Tower
Franz Schnider - General Manager of Arento AG
``Solar facades are cost-effective and contribute to the energy transition. That's because they produce valuable energy, especially in the winter months.``
Optimal integration into the facade

The Wattbuck residential development in Effretikon is a typical example of the architectural style of the 1960s and 1970s. For some of the high-rise buildings built around that time the second general renovation is now due – the ideal time to integrate solar power into the facade. The installation was easily integrated into the architecturally simple design of the facade by exploiting the parapets under the long window bands, which were previously clad with fibre cement panels. In addition to a well-insulated building envelope, around 470m² of photovoltaic modules were installed on the east, south and west facades. The 84 kWp system supplies valuable solar power, most of which is consumed directly on site.

Black photovoltaic modules are ideal for a simple and understated facade design.

PV modules are integrated as a cladding for the parapets.

The photovoltaic modules blend in smoothly with the basic architecture of the building.

Building characteristics
  • Building typology
  • Construction type
  • Year of construction
    1968, first renovated in 1982 and finally renovated in 2019
  • Energy reference surface
    4,292 m²
  • Energy index
    82 kWh/m²y (before); 31 kWh/m²y (after) per heating and warm water
  • Energy labelling
Franz Schnider - General Manager of Arento AG
``We still have a lot of comrades to find who will join us in our quest for a better energy future.``
Active solar surface  –  470 m²
Active solar surface ratio  –  <50%
Peak power  –  84 kWp
Building skin application  –  Cold facade
Storage NO
Energy production
Source: Arento AG
Measurements in progress
Building skin
  • Application
  • Description
    Compact flat roof with extensive greening and a insulation layer in EPS.
  • U value
  • Fastening system
  • Other
  • Application
    PV cladding integrated in a cold facade
  • Description
    Concrete walls insulated with 18 cm of glass wool. The non-active surface is covered with white fibre-cement panels.
  • U value
    0.17 W/m²K
  • Fastening system
    Hilti ventilated facade system
  • Other
    350 PV modules of identical size

Instead of fibre-cements panels, 350 PV modules were used as cladding in the areas under the windows.

  • Application
  • Description
    Triple glazing with PVC frame
  • U value
    0.6 W/m²K
  • g value
  • Other

The old PVC windows were replaced by new windows of the same material.

PV modules are used on the south, east and west facades.

BIPV module
  • Manufacturer
    Megasol AG
  • Cell technology
  • Front glass type/customization
    Fullblack, frameless glass/glass modules
  • Cell Colour
  • Dimensions
    1350 x 995 mm
  • Power
    240 Wp
  • Specific power
    178 Wp/m²
  • Weight
Technical details

PV modules were integrated in the parapets under the elongated window bands which were previously clad with fibre cement panels.

With an annual yield of approx. 600 kWh/kWp it is shown that buildings of a certain height (in this case a 13-storey building) are well suited in terms of energy production given that the facade area remains largely unshaded.

Hotspot image
Vertical section – roof edge
Hotspot image
  • Total cost of the building
  • Cubic meter price

With the right approach, older high-rise residential buildings can make an important contribution to a sustainable future.

Parties involved
  • Owner
    Pension fund of the Zürcher Cantonal Bank
  • General planner 
    Arento AG
  • Construction management
    Arento AG
  • Photovoltaic Installer
    Planeco GmbH
  • Photo
    Arento AG
Awards and recognitions
  • Awards
  • Publications
    Nachhaltig Bauen | 1 | 2019 – Solarfassaden an Hochhäusern – aktiver Beitrag zum Klimaschutz
  • Der Landbote / 21 May 2019 / Wände, die Strom produzieren
  • ZO/AvU /15 May 2019 / Solarstrom direkt ab der Hochhaus-Fassade
  • Aktives Hinwiler Gewerbe / May 2019 / Solarfassaden an Hochhäuser Beitrag zum Klimaschutz
  • Umwelt & Technik / Seite 120 – 122 / Aktiver Beitrag zum Klimaschutz