In the Marina del Prat Vermell (Barcelona), a project stands as a model for future social housing developments, addressing both the immediate housing shortage and long-term sustainability goals. By providing high-quality, affordable housing, it plays a key role in alleviating the housing crisis in Barcelona and sets a benchmark for similar projects worldwide.

La Marina del Prat Vermell, an old textile colony area established in Barcelona in the mid-nineteenth century, lies south of Montjuic mountain, near the sea. The neighborhood's name, "Marina del Prat Vermell," or the Red Meadow Marina, originates from the practice of dyeing and drying fabrics on the meadows. Now, this neighborhood represents the last public land development opportunities in the densely built city of Barcelona. Consequently, La Marina has become a strategic location for the city’s government to construct social housing units, such as the 72 units designed by MIAS Architects and Coll-Leclerc Arquitectos.

The plot, shaped like a triangle formed by the streets Ulldecona, Cal Cisó, and Pontils, influenced the architectural response. The design maintains the integrity of the triangular shape in its overall organization, without compromising the clarity and rationality of the orthogonal interior distribution of the dwellings. The three vertices of the plot are preserved as three closed corners, avoiding chamfers or simplifications.

To accommodate numerous social housing units, each with two rooms and optimal ventilation, solar exposure, typology, and views, the triangle is divided with two patios and two passages oriented from north to south, creating five volumes. The eastern and western corners house unique dwellings. Instead of using a layout with an interior triangular block courtyard, which would be too small and lead to an excess of north-facing dwellings, the proposal includes blocks of four corner dwellings, ensuring the two hours of solar exposure required by regulations between 10 am and 2 pm.

The perception of the complex varies depending on the viewpoint: from the eastern and western corners, it appears as a single unit block with gaps, while from the southern façade, five volumes are visible, allowing sunlight to penetrate through the passages at midday. This design avoids a continuous 92-meter façade and provides a smooth but intricate volume. The block's materialization or dematerialization changes based on the observer's position.

In summary, the building achieves a balance between being compact and porous. It is compact due to the triangle's geometry influencing its volumetrics, and porous due to the rationalized division into equivalent blocks. Each floor accommodates twelve residences, all featuring a corner layout, granting every unit dual orientation, ventilation, and complete solar exposure.

The material selection aims to minimize the building's carbon footprint by using lighter components and avoiding excavation in contaminated industrial soils. The facades feature alternating vertical strips of glass and ribbed GRC (fiber-reinforced concrete), red-colored and 17 mm thick, evoking the folds of fabrics drying on the meadow. Transported and positioned with their 120 mm metal frames, they are insulated on the inner face to ensure low thermal transmittance of 0.24 W/m2 K. The open corners have wide terraces that follow the envelope's geometry, protected by Gradhermetic louvers. The reinforced concrete structure uses a Bubble-Deck system, reducing the weight of the floor slabs by 35% and allowing the creation of cantilevers to adapt to the unique site geometry. The Bubble-Deck, composed of cylindrical bodies of recycled PVC, reduces weight and carbon footprint.

The project's shape factor, with openings designed to maximize solar gain in winter and provide shading and cross ventilation in summer on all floors, results in low total energy consumption of 8.76 kWh/m2 per year, achieving an A Rating and meeting Passivhaus standards with very low heating and cooling demands.

Ecoenergies' subway biomass network frees up the roof for the installation of a shared solar photovoltaic plant, consisting of 89 modules producing 37.8kWp, covering 51% of consumption. Vegetation is incorporated on the remaining roofs, and flowerbeds with red flowering species are planted along the access passages to promote biodiversity and mitigate the heat island effect. Additionally, bike racks are installed in these passages to encourage alternative mobility.

The importance of social housing in Barcelona cannot be overstated, especially in a city facing a deep housing crisis. With skyrocketing rents and limited space for new developments, many residents struggle to find affordable and adequate living conditions. In this context, the La Marina del Prat Vermell project emerges as a crucial intervention.

This project not only addresses the urgent need for affordable housing but does so with a forward-thinking design that enhances the quality of life for its residents. By integrating optimal conditions for ventilation, solar exposure, and dual orientation, the development ensures that each unit benefits from natural light and airflow, which are essential for healthy living environments. The use of sustainable materials and energy-efficient systems further underscores the project's commitment to environmental responsibility, reducing its carbon footprint and operational energy consumption.

The NOU LLOC Foundation's project in Barcelona's Ensanche, located in the 22@ district, faces the challenge of providing social housing in an area marked by gentrification and rising property prices. This building of 53 small social housing units (55 m² on average) is located on a chamfered plot and stands out for its innovative design that maximises space by eliminating corridors and creating a large communal courtyard. The 22@ district, known for its transformation from a former industrial zone to a modern technological hub, has made access to housing difficult due to growing demand and high costs. This social housing project not only addresses the urgent need for affordable housing in Barcelona, but also seeks to integrate the community into a dynamic and constantly evolving urban environment, thus addressing the challenges of gentrification and social exclusion.

In Barcelona, at the beginning of the 20th century, the 22@ district was born. 22@ is an ambitious urban planning project in Barcelona that seeks to transform a former industrial area into a modern district of new technologies and knowledge. This renewal plan has boosted the creation of innovative and sustainable spaces, attracting technology companies, start-ups and research centres. However, this transformation has also generated a gentrification effect, driving up housing prices and displacing original residents. Access to housing in 22@ and Barcelona in general has become increasingly difficult, exacerbating the city's housing crisis and posing significant challenges for those seeking to reside in this booming area.

It is to address these challenges that the Serra-Vives-Cartagena building was born. The project, promoted by the social housing-oriented NOU LLOC Foundation, faces an atypical programme for a chamfered plot in the Eixample district of Barcelona: 53 small dwellings (55 m² on average) and the relevant commercial premises on the ground floor.

The plot has the particularity of having a party wall open to a newly created public space. This results in a pentagon with four open facades and a party wall. The chamfer faces north and the new façade opens to the south-east. The adjacent building forms part of a consolidated complex 28 metres deep with a façade of remarkable values.

The distribution scheme that resolves the bulk of the residential programme is summarised in two bands of different depths and opposite orientations, separated by a central courtyard and articulated by the block of vertical accesses located in the pre-existing party wall.

The greatest complexity of the project arises from the strip facing the Tánger-Ávila streets, which must respect the alignment of the chamfer, so characteristic of Barcelona's Ensanche, and maintain the precise urban continuity of 19th-century Barcelona.

Both strips are aligned with the façade and the pre-existing backdrop. Access to the different dwellings is via interior walkways that converge in the only vertical access block that benefits from the courtyards of the neighbouring building. This composition creates a large courtyard on the ground floor that opens onto calle Ávila, with the vocation of an interior communal square. The most characteristic element of the building's image is to be found in the vertical cut of the chamfer, which reflects the dialogue between the two bands and opens up the inner courtyard to the light from the north.