The 54 Social Housing complex in Inca is an ambitious Spanish architectural endeavour commissioned by the Balearic Social Housing Institute (IBAVI). Known for its inventive architectural initiatives, IBAVI is a government agency dedicated to providing low-cost housing across the Balearic Islands in Spain. It undertakes small-scale housing projects to field-test new methods and local materials, that often pave the way for implementation in larger social housing projects across the country. Their past projects have seen experimentation with eco-friendly elements such as non-fossil-fuel-fired bricks and tiles, recycled wooden doors and dried Neptune grass thermal insulation. Usually, IBAVI appoints independent architectural firms to design the interventions such as in the case of this sustainable housing project, which is designed by Joan Josep Fortuny Giró and Alventosa Morell Arquitectes, distinguished Spanish architects known for their residential architecture projects in Spain.

In their collaboration with IBAVI, the architects were driven by a clear vision and a common goal: to foster a community that coexists harmoniously with its context while minimising environmental impact. The project's site, owned by IBAVI, is a rectangular plot in the small town of Inca, measuring approximately 3,266 square metres.

The design process for the 54 Social Housing units began with two fundamental aspirations: ensuring the correct insertion of the building into its urban and natural context and creating a cohesive blend of the spatial and functional needs of the programme. Responding to the programme brief from the IBAVI, the design team devised a layout that evenly distributed the 54 units in sets of 18 per floor within a ground-plus-two scheme. Each unit was strategically designed to open out to either a terrace or a private garden, while between the units are shared breakout spaces that encourage a sense of community among residents. Additionally, an underground parking facility has been incorporated to meet municipal programme requirements.

The massing of the complex predominantly follows a north-south axis, achieved by splitting the built mass into two independent volumes, maximising natural light exposure and creating a large public courtyard in between. The architects intelligently positioned the two three-storey slab-like buildings at an angle to each other, forming a closed apartment block with a central north-south axis for access.

Internally, the apartments are organised around a central stairwell and elevator core, with each unit featuring a central sanitary core flanked by living areas and bedrooms. The orientation of the apartments varies across floors, with ground-floor units facing the inner courtyard, while upper-level units offer panoramic views of the Serra de Tramuntana mountain range or glimpses of the neighbouring street. Each unit's mass is carved to optimise sun and wind orientation while also ensuring privacy, resulting in uniquely designed units on each floor. The outdoor spaces such as the gardens and terraces feature low-maintenance gravel areas, complemented by trees for future shade.

Evidently, at the heart of the development lies a commitment to energy efficiency, attested by its designation as a Net Zero Energy Building (NZEB) with a remarkably low energy demand of 0.65 kW/m²/year, setting a new standard for future urban developments in the region. This achievement is attributed to a combination of passive design strategies and active renewable energy systems.

The integration of various passive bioclimatic strategies into the design enhances both comfort and sustainability. The layout of the units facilitates cross ventilation from opposing facades, ensuring optimal airflow. The facade incorporates openable wooden shutters, louvred for solar protection, to mitigate heat gain during warmer months. The thermal mass and inertia provided by concrete slabs and ceramic coatings stabilise indoor temperatures, reducing the need for artificial heating and cooling. Similarly, active strategies which include photovoltaic panels and an Aerothermia system for heating and ventilation, have also been implemented, further reducing the energy loads.

Sustainability, however, extends beyond energy consumption and includes water conservation and waste management. The building is detailed such that rainwater is collected from roofs, redirected and stored in cisterns for reuse. Exterior pavements have also been designed to allow 85 per cent drainage, enabling water to permeate the soil and replenish groundwater reserves, crucial in a region prone to water scarcity.

The project employs materials and construction practices that prioritise locally sourced, low-impact options. From ceramics fired in a biomass oven to wood sourced from sustainably managed forests, every material choice is guided by a commitment to reducing the architecture’s carbon footprint.

In line with this commitment, the facade enclosures have also been meticulously designed, featuring a double ceramic layer with recycled cotton insulation in between, externally insulated with sprayed cork and lime and finished with natural pigments. The exterior joineries utilise materials such as aluminium with thermal break and certified Larch wood for sun shielding louvres. Similarly, the flat roof incorporates an inverted insulation and waterproofing system using recycled gravel, whereas the interior pavements are crafted from locally sourced clay ceramics.

On the street-facing sides, ceramic cladded plinth gives way to the exposed brick garden walls within the inner courtyard. The pale green window frames and balcony parapets harmonise with the facade pillars, creating a lively contrast to the surrounding natural hues. For the interiors, ceramic tiles were selected and matching that, the brick partition walls in the apartments were painted while ceilings were coated in perlite plaster.

Structurally, the building employs a robust system of metal pillars and 35 cm thick ribbed concrete slabs, allowing for large column-less spans. The underground level is supported by concrete retaining walls and a foundation system of micro-piles and footings. The construction began at a higher level, gradually descending with the slope, resulting in an accessible pathway and vibrant community spaces on the ground floor lined with Jacaranda trees, offering both shade and aesthetic appeal.

In essence, this public housing project in Inca serves as a prototype of sustainable architecture and development, while providing an easily constructible and replicable design solution, appropriate for the urgent needs of social housing schemes of this nature.