IN Brief:
- Werner Sobek has engineered the facade for DC Tower 2 in Vienna.
- The 175m tower integrates around 12,000 sq m of photovoltaic modules into its east, west, and south elevations.
- The system targets an annual energy yield of 800,000 to 1,000,000 kWh from the building envelope.
Werner Sobek has engineered a double-skin facade for DC Tower 2 in Vienna, integrating around 12,000 sq m of photovoltaic modules into the high-rise envelope.
The 175m tower is being built in Donau City and will complete the DC Towers ensemble, around 12 years after the completion of DC Tower 1. The 53-storey building has been designed by Dominique Perrault Architecture with Hoffmann-Janz Architects and will combine residential, office, catering, and co-working space.
Werner Sobek is responsible for the facade engineering, as it was on DC Tower 1. The facade system consists of two layers: an inner thermal structure using triple-glazed insulation with openable sashes, and an outer perforated shell. The outer layer combines fall-protection laminated safety glass, photovoltaic modules, parapet glazing with bird protection, and open areas designed to relieve wind pressure.
Photovoltaic modules are integrated across the east, west, and south sides of the tower. They cover around 12,000 sq m of the approximately 24,000 sq m total facade area and are expected to generate between 800,000 and 1,000,000 kWh annually. Two-storey post-and-beam special facades are also being installed on the ground floor and top floor.
The project takes the high-rise facade beyond weather protection, daylight control, and visual identity. It turns the building envelope into part of the operational energy strategy. That approach is likely to become more common as developers, designers, and asset owners face tighter carbon expectations, higher electricity demand, and limited roof area on tall buildings.
Vertical photovoltaic integration is not a simple substitute for rooftop solar. Facade modules face different solar exposure, shading, wind loads, maintenance access, fixing requirements, and fire-safety considerations. On a tall building, those issues sit alongside movement, thermal performance, airtightness, acoustic control, cleaning, replacement access, bird protection, and long-term warranty management.
DC Tower 2’s envelope has to perform as facade, safety barrier, weather layer, ventilation interface, and power-generating surface at the same time. That creates a coordination challenge across architecture, facade engineering, structural design, M&E, energy modelling, maintenance planning, and construction logistics.
The double-skin arrangement is central to that balance. The inner layer provides the controlled thermal line, while the outer perforated shell supports the photovoltaic and protective elements. Open areas in the outer shell relieve wind pressure, an important feature on a 175m tower where facade loads and comfort conditions differ materially from those on mid-rise commercial buildings.
The project also reflects a wider shift in European building design. As operational carbon targets become more demanding, building envelopes are being asked to contribute actively to energy performance. Facades that once carried only aesthetic and environmental-control functions are now being evaluated for solar generation, shading, embodied carbon, circularity, and maintenance impact.
That does not remove the need for efficient building services or grid connection. A high-rise with mixed uses will still rely on broader energy systems, demand management, and plant performance. DC Tower 2 shows a facade engineered as one of those systems, rather than treated as a passive outer skin.
For contractors and facade specialists, active envelopes can increase building performance while increasing the burden on design coordination, installation quality, commissioning, and long-term asset management. DC Tower 2 shows where premium high-rise facade engineering is heading: towards envelopes that must generate, protect, regulate, and endure.