El futuro de la construcción modular

Modular construction encompasses the manufacture of complete volumetric components or modules in controlled industrial environments, with subsequent on-site assembly. The global market reached 91 billion USD in 2023, and projections from Fortune Business Insights estimate it will reach 139 billion USD by 2030, with a compound annual growth rate (CAGR) of 6.1%. The main segments are: volumetric modules (complete 3D units with integrated services, 48% of the market), 2D panels (prefabricated walls, floors, and roofs, 35%), and hybrids (17%). By geography, Asia-Pacific leads with 42% of the global share (Japan: 16% of new homes are modular; China: 6% and growing), followed by Europe (30%, with Sweden reaching 84% of single-family homes in prefabricated timber) and North America (22%).

The factors driving this growth are quantifiable: the shortage of skilled labour (the EU construction sector records 400,000 vacancies according to Eurostat, 2023), the ageing workforce (average age of a construction worker in Spain: 47 years), regulatory pressure on waste (the Waste Framework Directive requires a recovery rate of 70%), and the need to reduce timelines (public housing in the UK requires 300,000 new units/year versus the 210,000 produced). Modular construction in Spain remains at an early stage: it represents less than 3% of new homes, compared to 10-15% in Germany and 20-25% in the Scandinavian countries. The Spanish State Housing Plan 2022-2025 includes incentives for industrialisation, with an allocation of 50 million euros for industrialised construction pilot projects.

Timeline reduction is the most consistent competitive advantage of modular construction. A meta-analysis of 86 modular projects (Kamali and Hewage, 2016) quantified an average construction timeline reduction of 30-50% compared to traditional construction, attributable to the overlap of activities: factory manufacturing runs concurrently with foundation and site works, eliminating the sequential critical path. The British company L&G Modular Homes built 44 dwellings in Selby (Yorkshire) with volumetric modules produced at its 55,000 m² factory in Leeds, completing on-site assembly in 5 days per dwelling (compared to 16-20 weeks in traditional construction). The Japanese factory Sekisui House, operational since 1960, produces 10,000 homes annually with a manufacturing time of 85 days per unit and on-site assembly of 1-3 days.

Waste reduction is equally well documented. Jaillon and Poon (2014) demonstrated in a study of 16 projects in Hong Kong that prefabrication reduces construction waste by 52% compared to in-situ construction, with specific reductions of 74% in timber waste (formwork), 63% in concrete, and 48% in steel. Factory production enables the reuse of offcuts: steel trimmings are returned to the supplier for remelting, plasterboard remnants are recycled at 95%, and sawdust from timber is directed to pellet or particleboard manufacture. In cost terms, the McKinsey Global Institute (2017) estimates a potential reduction of 10-25% in total construction cost when industrialisation reaches scale, although isolated low-volume projects can be 5-10% more expensive due to investment in moulds and transport logistics. The break-even point occurs at production volumes above 200-500 units/year with standardised module designs.

The integration of robotics into modular production lines is transforming factories into advanced manufacturing facilities. The Swedish company BoKlok (a joint venture between IKEA and Skanska) operates factories with 6 robotic stations that perform CLT timber cutting with a precision of ±0.5 mm, automated screwing (2,400 screws/hour), joint sealing, and painting. Productivity reaches 1 complete module every 4 hours, with 12 workers per shift compared to 30-40 on an equivalent manual line. The American company Factory OS (Oakland, California) produces volumetric modules of 4.2 x 15.2 m for multi-family buildings of up to 8 storeys, with an output of 2,000 modules/year and a cost 20% lower than conventional construction in the San Francisco Bay Area. In Japan, Shimizu Corporation has developed the Shimz Smart Site system that employs autonomous robots for beam welding (6 kg of weld/hour with quality certified at 99.8%), material transport, and surface finishing.

BIM-to-fabrication integration enables direct digital flow from the 3D model (LOD 400-500) to factory CNC machines, eliminating the reinterpretation of drawings and reducing dimensional errors from 3-5% (traditional construction) to 0.1-0.3%. Platforms such as Autodesk Revit with fabrication plugins (AGACAD, Vertex BD) automatically generate cutting lists, assembly drawings, and G-codes for CNC machines. 3D concrete printing is advancing toward integration with modules: the Danish company COBOD (BOD2 Printer) prints concrete walls at 1 m/s with layers of 30 mm x 60 mm, completing the walls of a 100 m² dwelling in 48 hours. The TECLA project (Massa Lombarda, Italy, 2021, Mario Cucinella Architects + WASP) demonstrated the 3D printing of a complete dwelling using local raw earth in 200 hours, with a material cost below 1,000 EUR. The convergence of these technologies points toward modular 4.0 factories capable of producing a complete dwelling in 10 days from order confirmation.

The environmental impact of modular construction has been quantified through life cycle assessment (LCA). A study by Quale et al. (2012), published in Energy and Buildings, compared 4 modular homes with 4 equivalent conventional homes in Virginia (USA) and found that the modular homes generated 43% fewer CO₂ emissions during the construction phase (LCA modules A4-A5) and 36% less solid waste. Reduced exposure to weather during factory manufacturing decreases airtightness defects by 50-70%, improving the airtightness of the completed building: Blower Door tests on timber-frame modular homes report average values of n₅₀ = 1.5-3.0 ach, compared to 5-10 ach in traditional construction without specific control. Greater dimensional precision improves the effective thermal performance of the envelope by 10-15% above the theoretical value, by eliminating thermal bridges caused by construction defects.

The sector's outlook points in three converging directions. The first is modular standardisation: CEN TC 434 (European Committee for Standardization) has been working since 2019 on a European standard for volumetric modules that will establish tolerances, connections, and performance requirements for a single European market. The second is high-rise modular construction: the building at 461 Dean Street (Brooklyn, New York, 2016, SHoP Architects, 32 storeys with 930 modules) demonstrated the viability of steel modular skyscrapers, while Mjostarnet (Brumunddal, Norway, 2019, Voll Arkitekter, 85.4 m, 18 storeys) is the world's tallest timber building, constructed with cross-laminated timber (CLT) and glued laminated timber (glulam) modules. The third is circularity: design for disassembly (DfD) enables modules to be relocated at the end of the building's service life (50-60 years), with potential material reuse rates of 70-90% of structural material. The future of modular construction is shaping up as the industrial transformation of the building sector, delivering simultaneous improvements in quality, timeline, cost, and sustainability.