When you picture the world’s best building of the past couple of years, perhaps a gleaming glass skyscraper or museum springs to mind. But the 2024 winner of the prestigious biannual RIBA International Prize is a building type rarely associated with being ‘the best’—social housing. Modulus Matrix, a six-story housing development of 85 socially rented homes in Cornellà de Llobregat, Spain, designed by Barcelona firm Peris + Toral Arquitectes, took the plaudits. RIBA president Muyiwa Oki described it as a “blueprint for delivering sustainable, quality housing around the world at scale.”
While impressive, in Spain, Modulus Matrix is not a one-off. Over the last decade, local governments across the country have been steadily building social housing that defies the prejudices these types of projects are often associated with, incorporating sunbathed balconies, generous communal spaces, natural materials, and passive design principles to improve the experience of living there for residents and even help minimize energy bills.
This has come at a time when cities across Spain are facing challenges similar to many others globally: increasing evictions, growing energy poverty, people living in substandard and overcrowded housing, and skyrocketing rents. Given its high levels of tourism, Barcelona’s housing shortage has been compounded by a spate of properties being converted to short-term rentals, which can generate two to four times the usual profit for owners and has seen vacation rentals boom to over a quarter of the rental housing stock in some neighborhoods, pricing many locals out. In June, the city announced plans to ban short-term rentals by November 2028. But Barcelona started tackling its housing crisis years earlier, setting out an ambitious Right to Housing Plan, 2016-2025 with a wide-reaching series of goals, from improving housing-related IT infrastructure to doubling its social housing provision.
Barcelona firms MIAS Architects and Coll-Leclerc completed 72 social housing units in the Marina del Prat Vermell neighborhood in 2023. The facade features alternating vertical strips of glass and ribbed fiber-reinforced concrete. The triangular building’s openings are designed to maximize solar gain in winter and provide solar shading and cross ventilation in summer on all floors.
The Plan was championed by Ada Colau, Barcelona’s former mayor (from 2015 to 2023), who inherited a city with a paltry social housing stock of just 7,500 homes for a population of 1.6 million, due to widespread sell-offs on the private market. Eduardo González de Molina, a policy advisor with Barcelona’s council housing unit, described the Plan’s long-term vision as “Vienna 2.0,” referring to the Austrian city’s legendary housing success, where a quarter of the population are social housing tenants. Despite being ousted in June 2023 by socialist Jaume Collboni, Colau’s time as mayor helped kickstart serious efforts to finally upgrade the city’s social housing sector that are being carried forward by Collboni.
The Plan’s ambitious rhetoric is, importantly, backed by financial clout, with €1.7 billion of direct contributions from the City Council—77 percent more than the annual average spend in previous years—and close to €3 billion in public and private funding earmarked over ten years, or around €300 million a year. (For comparison, Vienna’s social housing budget is said to be closer to €400 million, though the city also has a larger population of two million.) Through the Plan, the city has been purchasing existing buildings and buying up vacant apartments at 50 percent their market rate to increase its social housing stock. Barcelona’s municipal organizations have also run social housing architectural competitions, giving established and emerging Spanish firms the chance to cut their teeth with innovative social housing designs.
“The best architects, they participate in competitions for social housing, even if the conditions are not very good—they’re not the best paid projects, but they have a lot of status,” says architect Carles Baiges Camprubí of Lacol, a Barcelona practice that specializes in cooperative housing.
The conventional approach in apartment design is to locate rows of cellular units along either side of a long, central passage—a model referred to as a “double-loaded corridor.” This can waste circulation space and limit opportunities for light and cross ventilation. Much of Barcelona’s new-build social housing outright rejects this, with architects instead opting for layouts that are compact and standardized, but also offer greater possibilities for social interaction between residents, along with more access to sunlight and air.
For instance, at the 67 publicly subsidized dwellings in Barcelona’s La Trinitat Nova neighborhood, completed in 2023 by Narch Arquitectes, Maira Arquitectes, and dataAE, access to each apartment is via a private terrace connected to a partially open hallway and stairwell, with just two units on either side of the landing. This allows each open-plan living space to span the width of the structure, channeling breezes through openings on both ends. Balconies on the east and west also provide every unit a place to sit in the sun in the morning and evening—the kind of experience typically reserved for luxury apartments. At Baró Tower, a housing block with 47 state-subsidized units completed by the same three firms the year prior, groups of four apartments are also accessed via shared, open terraces connected to a central atrium. This means each apartment can open up on three sides, offering light and through-breezes. The atrium provides a communal space for the building and can be opened and closed in different seasons, trapping warmth during winter, or expelling excess heat using the stack effect in summer. Across both buildings, natural materials like brick, ceramic tile, timber, and stone are all used in abundance.
Peris + Toral Arquitectes, the same Barcelona firm behind the 2024 RIBA International Prize–winning Modulus Matrix, designed Borrassá, a mixed-used building with 54 social housing units, in the city’s Besòs district. The brick lattice walls help ventilate the atrium.
The use of mass timber is another common feature of several recent social housing projects in Barcelona to both speed up construction and reduce embodied carbon (the amount of greenhouse gas emissions that occur during the construction of a building). The award-winning Modulus Matrix, for example, used 8,300 cubic meters (10,856 cubic yards) of Spanish-harvested timber for the floors, walls, and solid wooden stairs. Its modular layout means every room is the same size—3.6 by 3.6 meters (11.8 by 11.8 feet)—creating apartments that can be easily reconfigured over time, while also reducing build cost. At 151 social housing apartments completed in Barcelona’s Sant Martí district in 2024, the use of prefabricated timber panels reduced construction time from two years to one, while also reducing carbon emissions by 30 percent.
Innovative design approaches mean quality is achieved despite tight budgetary constraints. In Barcelona firm MAIO’s scheme for a four-story, multifamily building with 40 social housing units, shading is provided by wrapping the building in experimental fabric curtains. This low-cost, low-maintenance approach helped construction costs come in at €950 per square meter (about $92 per square foot), almost half the national average of €1,700 per square meter (around $165 per square foot).
Beyond conventional social housing, Barcelona’s City Council has also created a cooperative housing committee to facilitate cohousing, a model in which the city or a private owner provides a property or abandoned site for a cooperative group to build on and occupy for up to 50 to 100 years, with construction often financed by socially responsible banks. The cooperative pays a deposit and monthly installments at below-market prices, but since the housing is not for profit, these payments can be around 40 percent lower than average rents in the city.
As their name suggests, cooperatives also promote more communal living. At La Borda, a 28-unit “self-organized” cooperative designed by Lacol in 2018, residents have access to generous shared amenities and facilities, including a large, open multipurpose space, kitchens, laundry, guest rooms, and more. Since the cooperative is the client for the build (rather than a generic developer), it also creates a more participatory design process, giving those who will actually live there a voice on the architecture. According to Camprubí, this means cooperatives look and feel different to typical apartments “because we had the opportunity to discuss with people, to propose them alternatives, and they could evaluate them and decide whether or not they wanted to take the risk.”
Spain’s social housing revolution has also seen the creation of homes catering to groups explicitly failed by market-led housing provision. Barcelona firm Vivas Arquitectos’s 100-person Reception Center for Homeless Women is a simple rectilinear block built from thick cross-laminated timber (CLT) walls with a series of interior terraces and balconies. Its metallic facade shimmers in the Catalonian sun, creating an aesthetic that feels more like a contemporary arts museum than subsidized housing or a shelter.
Joan Josep Fortuny Giró and Alventosa Morell Arquitectes designed 54 social housing units in Inca, a town on the Spanish island of Mallorca, on a plot owned by the Balearic Housing Institute (IBAVI). Each of the units have outdoor spaces: private gardens on the ground level, and terraces on the upper floors. Sustainably extracted larchwood sun shields cover much of the facade.
But the effort isn’t just in Barcelona: Similar buildings are emerging across Spain, from Balearic Housing Institute (IBAVI)–sponsored social housing projects made from local sandstone and ceramic blocks with recycled cotton insulation in Mallorca, to a 159-unit social housing project in Madrid organized around a network of indoor and outdoor plazas.
Still, any sense that Spain has cracked the housing crisis is misleading. For instance, Barcelona may now have the largest public housing stock in the country, with a reported 12,300 social homes by the end of 2023, but this is far from enough. In Europe, around 15 percent of homes are socially rented; in Catalonia it’s closer to two percent. “Social housing is being built with great architectural quality, but the amount of housing of this type produced in Barcelona is still insufficient to meet the abundant demand,” says Anna Gener, CEO of real estate consultancy firm Savills Barcelona.
The challenge has never been more apparent, with tens of thousands marching across the city in November to protest escalating rents. Barcelona’s next Housing Plan, which will run from 2025 to 2032, promises a rethink of current policy as the city continues to aspire for housing as a fundamental right for all.
