In Barcelona’s 22@ innovation district, a former industrial area transformed into a thriving technology hub, the Sea Towers Office Building rises as a new model of sustainable architecture. Designed by GCA Architects, the project demonstrates how modern office buildings can move beyond passive sustainability strategies and become active producers of renewable energy.

Rather than treating solar energy as an external addition, the architects integrated it directly into the building envelope through Building Integrated Photovoltaics (BIPV). The result is a façade that does more than protect the interior—it generates electricity, filters daylight, and enhances environmental performance.

Sea Towers illustrates an important shift in architecture: the building skin itself becomes part of the energy infrastructure of the city.

The complex consists of two office towers of six and twelve floors, designed with strong environmental ambitions and a focus on occupant wellbeing. The architecture integrates open terraces, natural daylight, and vegetation, creating flexible workspaces connected to the Mediterranean climate.

However, the most distinctive feature of the project lies in its energy-generating façade, where solar technology becomes an integral part of the architectural design.

BIPV Integration: The Solar Curtain Wall

The most innovative element of the project is the photovoltaic glass integrated directly into the curtain wall façade.

Instead of mounting solar panels on top of the building, Sea Towers integrates solar cells inside glass panels, making the façade itself capable of producing electricity.

Photovoltaic Façade System

The solar façade uses amorphous silicon photovoltaic glass manufactured by the Spanish company Onyx Solar.

Key characteristics of the BIPV installation include:

• 1,520 m² of photovoltaic glass integrated into the curtain wall
• Approximately 1,000 photovoltaic glass units installed
• Custom-designed modules adapted to the façade geometry
• Integrated insulating glass units with 12 mm air chambers to improve thermal and acoustic insulation

Each photovoltaic glass panel performs several architectural and environmental functions simultaneously:

• façade cladding
• solar electricity generation
• daylight filtering
• thermal protection

This multifunctional approach is the essence of Building Integrated Photovoltaics, in which solar modules replace conventional building materials rather than being added later.

Performance of the Solar Glass
The photovoltaic glass façade is carefully designed to balance energy production, daylight access, and indoor comfort.

Technical characteristics include:

• Nominal power: up to 34 Wp per m²
• Visible light transmission: approximately 20%, allowing natural daylight while reducing glare
• Solar heat gain coefficient: around 32%, helping control heat entering the building

Through these properties, the BIPV façade contributes to several environmental benefits:

1️⃣ Generation of renewable electricity
2️⃣ Reduction of cooling loads during summer
3️⃣ Improved daylight quality inside offices
4️⃣ Enhanced acoustic insulation

The façade, therefore, acts as a high-performance environmental filter, adapting the Mediterranean sunlight to create comfortable interior spaces.

Beyond Energy: A Holistic Sustainable Building

While the solar façade is the most visible innovation, Sea Towers incorporates several additional sustainability strategies.

Rooftop photovoltaic panels complement the façade generation, increasing the building’s renewable energy production.

Green terraces and rooftop gardens improve thermal performance while providing outdoor spaces for building occupants.

The project also promotes low-carbon mobility by integrating electric-vehicle charging stations, bicycle parking, and pedestrian-friendly public areas.

These combined strategies allow the building to achieve significant environmental improvements, including:

• 52% reduction in energy consumption
• 66% reduction in water consumption

The project ultimately earned LEED Platinum certification, one of the highest sustainability recognitions in the building industry.

As cities aim to reduce carbon emissions and transition to renewable energy, the role of buildings becomes increasingly important. Facades and roofs represent vast, often unused surfaces capable of generating solar power.

Sea Towers Barcelona offers a compelling vision of this future.

By transforming its façade into an energy-producing system, the project demonstrates how architecture can simultaneously deliver aesthetic quality, environmental responsibility, and technological innovation.

In the solar cities of tomorrow, buildings will not simply reflect sunlight—they will capture it, convert it, and help power the urban landscape.

Sea Towers is already pointing the way forward.