Architectural media seems singularly focused on the image of completed buildings. This isn’t a hot take and in fact, feels only right; what can one make of a building before it is finished apart from what we can tell from renders (with renders often being outrageous in their own way, like a certain controversial city in Saudi Arabia one might think of)? What is architecture before one knows how it feels to walk down its corridors or gaze out of its windows, before one knows what the window frames? But what of the window frames?

While the notion that architecture is only an act of spatial embodiment or that it’s only worth talking about architecture once complete or occupied might be fair, it’s still vital for a discipline deeply engaged in processes of building to think about who builds and the materials that go into the building.

In relation, what of the materials that have gone into a building? Where did they come from? Were the window frames constructed from uPVC and would they be recyclable? Were there any off-cuts left over that had to be discarded? Or were they made from locally sourced wood, hence cutting down on transportation costs? These are relevant questions one needs to ask in a world where every year is the hottest in recorded history until the next one. This is not the typical story one reads on a website that often talks about the processes of architecture. This is a story in progress; the story of construction. Particularly, the following presents the tale of a social housing block's construction in Mallorca. Designed by H Arquitectes, a Barcelona-based architecture practice, the housing complex is meant to provide 25 housing units for elderly people in Palma de Mallorca. Where the plot for the building was delineated stood an old, abandoned school.

It’s a common sight in any urban context today. While scaffolding goes up around each corner (a sign of incessant development), others are marked by buildings no longer in use, disintegrating. Soon, plants will grow out of them and animals will make them their home. Recent adaptive reuse projects have looked to such ‘ordinary structures’, recontextualising and updating them for use as required. Such schemes hope that the refurbishment of the built environment presents a sustainable path, cutting down on material costs and the carbon footprint generated by conventional construction.

However, the school building that stood on the plot for the upcoming social housing could not be retrofitted. “There was no possibility of preserving [the building]. It [was] a small disused school, with three floors, built with structural sandstone walls and concrete and ceramic roofs,” the design team notes.

Forgoing preservation, the materials that the erstwhile school building used could still be reclaimed for the housing, after demolition. This method of reusing debris, often called ‘urban mining’, was employed by the design team for the complex. “The material resources come from the (urban) plot itself,” they reiterate. Presenting a pertinent example of circular economy principles in construction, the method significantly cuts down on materials needed, apart from the waste and carbon generated by the process of building. Currently, the construction industry in Spain generates around 20 per cent of the country's total CO2 emissions, with carbon being emitted in processes of material extraction, transportation and assembly and in the running of any building. Hence, energy efficiency and resource optimisation are tantamount to any architectural project today.

The Spanish architects exhaustively list the amount of materials reused for the project in the official release, stating, “Once the demolition is finished and the materials selected, almost all the debris from the work will be used, depending on the type of material, mainly in two ways: the pieces of ceramic elements and concrete will be poured (140 cum) in the foundation wells and the whole marès stone (160 cum) will be reused to build large blocks (1,700 units) of cyclopean concrete mixed with recycled marès (40 per cent of the volume of the blocks), composed of large rocks up to 30cm in diameter, marès gravel and crushed stone (sand, also from Marès).”

The stones and aggregate generated will be utilised to create prefabricated blocks. “These blocks, about 135 cm long, 42 cm high and a variable width for each floor (64, 54, 44 and 34 cm), will be prefabricated once the demolition is finished before construction begins of the new building and will make it possible to considerably reduce the duration of the works,” H Arquitectes promises.

Under construction for about two years at the time of writing, the scheme for the social housing is simple. The architects envisioned a structure where the blocks created through the reuse of existing materials are stacked, creating load-bearing walls that support laminated timber ceilings. On subsequent floors, the walls are thinned by 10 cm, allowing the direct support of the wooden panels and speedy construction. The use of load-bearing walls further reduces the need to use concrete and rebar. (Concrete, through its very composition, ends up producing about 0.8 to 0.9 tons of CO2 emissions, which contributes to about 8 per cent of the total anthropogenic CO2 emissions.)

The layout for the residential architecture is simple as well, with an L-shaped plan organised around the staircase design, placed at the corner of the L. This enables the creation of an internal courtyard design that facilitates access to each dwelling and serves as a communal gathering space for its residents. The facade design for the block is minimal, exposing the structural system of the prefabricated elements, while the apartment units feature large wooden balcony frames that give a sense of rhythm to the design. The mined, terrazzo-like quality of the prefabricated architecture adorns the facade, giving it a distinct aesthetic that still echoes the existing context.

The architects have previously explored circular design through the reuse of demolition waste in a residential project completed in 2017. Similar to this housing scheme, the designers used load-bearing walls fabricated from stones gathered from the demolition of an existing structure.

Commissioned by the Balearic Institute of Housing (IBAVI), a government organisation that develops housing projects with an attempt to expand methods that use local or environmentally friendly materials, Social Housing 2104 presents a fine case study, even (and especially) in its incomplete state. While we move towards an architectural culture that champions retrofitting, discourse around sustainability and the need to reduce carbon still tends to veer towards the technocratic, looking for new technologies, new materials, newer ways of doing things. What we need, instead, are more stories that look to work with the existing, even for material reuse.

Project Details

Name: Social Housing 2104/ 25 endowed housing units in Palma de Mallorca 
Location: Palma de Mallorca, Mallorca, Spain
Design Team: David Lorente, Josep Ricart, Xavier Ros, Roger Tudó
Collaborators: Anna Burgaya, Ángeles Torres, Cynthia Rabanal, Victor Jorgensen
Team: Xavier Suárez (quantity surveyor), DSM-arquitectes (structure), M7 enginyers (engineer), Societat Orgànica (environmental consulting), MC acústica (acoustics engineer)