Construcción tradicional vs. moderna desde una perspectiva verde

The comparison of embodied carbon between traditional and modern construction systems constitutes the most telling indicator from a green perspective. The meta-analysis by Skullestad et al. (2016), published in Energy and Buildings, evaluated 13 pairs of real buildings ranging from 3 to 21 stories with timber and reinforced concrete structures that fulfilled equivalent functional programs, and found that timber structures present embodied carbon 34-84% lower (average of 45%) in LCA modules A1-A3 (extraction, transport, and manufacturing). In absolute terms, conventional reinforced concrete structure generates 250-500 kg CO₂eq/m² of built area, steel structure 200-400 kg CO₂eq/m², CLT timber structure 120-250 kg CO₂eq/m², and rammed earth 15-80 kg CO₂eq/m². The EPD database on the One Click LCA platform, with more than 120,000 verified environmental product declarations, allows quantifying these differences at the component level and verifying that the ranges remain consistent across manufacturers and climate regions.

However, a fair comparison requires considering the full life cycle. Concrete exhibits a carbonation phenomenon (reabsorption of atmospheric CO₂) that recovers between 15% and 25% of the CO₂ emitted during cement manufacturing over a period of 50-100 years (Xi et al., 2016; Nature Geoscience). Timber, for its part, stores approximately 1,600 kg CO₂/m³ of biogenic carbon, but this is released if the material is incinerated at end of life instead of being reused or recycled. Earth (rammed earth, adobe) is the material with the lowest end-of-life impact: it can be returned to the ground without processing. A complete life cycle study (A1-C4) by Peñaloza et al. (2016), published in Building and Environment, compared 4 construction systems for an 8-story residential building in Sweden and concluded that the CLT structure with accredited biogenic carbon storage presents a net GWP of -50 to +80 kg CO₂eq/m², compared to +280 to +420 kg CO₂eq/m² for reinforced concrete, a difference ranging from 200 to 470 kg CO₂eq/m² depending on the end-of-life scenario considered.

The operational energy efficiency of buildings depends on the envelope strategy, where tradition and modernity offer complementary solutions. Vernacular buildings in Mediterranean and arid climates use high thermal mass walls (300-600 kg/m²) with inertia that stabilizes indoor temperature, natural cross ventilation, shading through overhangs and vegetation, and light-colored facades with solar reflectance of 0.60-0.85. A study by Fernandes et al. (2015), published in Energy and Buildings, monitored 8 vernacular dwellings in the Portuguese Alentejo (rammed earth walls of 60 cm, tile roof over reed matting) and documented indoor temperatures between 19 and 27 °C without mechanical conditioning for 83% of annual hours, with a total energy consumption of 22-38 kWh/m²·year. In contrast, modern conventional dwellings in the same region (brick wall of 25 cm without insulation, built in the 1980-2000 period) registered consumption of 85-140 kWh/m²·year.

High-performance modern construction achieves even lower consumption when it combines advanced insulation with active technology. A typical Passivhaus building in a continental climate presents heating consumption below 15 kWh/m²·year and total primary energy consumption below 120 kWh/m²·year, achieved through continuous insulation of 25-40 cm (transmittance of 0.10-0.15 W/m²·K), triple-glazed windows (Uw ≤ 0.80 W/m²·K), airtightness (n50 ≤ 0.6 ACH), and mechanical ventilation with heat recovery efficiency above 85%. The key from a green perspective is not to choose between tradition and modernity, but to integrate both approaches. Enhanced vernacular architecture combines the thermal mass of earth or stone walls with interior aerogel insulation (10-20 mm), mechanical ventilation with heat recovery, and dynamic solar protection, achieving consumption of 20-35 kWh/m²·year with embodied carbon 40-60% lower than the conventional Passivhaus solution with concrete structure and synthetic insulation, according to the comparative study by Galán-Marín et al. (2018), published in Sustainability.

The circular economy applied to building construction clearly favors traditional construction systems, whose material separability and reuse potential surpass those of modern systems. A dry stone wall is 100% reusable without processing: stones are disassembled and reassembled indefinitely. A rammed earth wall can be demolished and the earth recompacted into a new wall, with a recyclability rate of 95-100% and virtually zero recycling energy consumption. In contrast, demolished reinforced concrete generates recycled aggregate whose use is limited to 20-30% substitution in new structural concrete (EHE-08, annex 15) and its processing (crushing, screening, rebar separation) consumes 15-30 kWh/ton. The effective recycling rate of concrete waste in Spain is 40%, compared to 90% in the Netherlands (Eurostat, 2022). The Material Circularity Indicator (MCI) from the Ellen MacArthur Foundation, applied by the Dutch CB'23 project to 25 buildings of different construction typologies, assigned values of 0.75-0.90 to timber buildings with demountable connections (screws and plates), 0.60-0.80 to stone and earth buildings, and 0.15-0.35 to cast-in-place reinforced concrete buildings.

Design for Disassembly (DfD) allows modern construction to approach the circularity of traditional methods. Steel structure systems with bolted connections, CLT floor slabs placed without adhesive, and ventilated facades with mechanical fixings achieve an MCI of 0.70-0.85, comparable to demountable traditional systems. The Circle building at Zurich Airport (2020, 180,000 m²) was designed with a materials passport documenting 45,000 components and their disassembly instructions, estimating recovery of 80% of materials at the end of the 60-year service life. However, 92% of modern buildings are not designed for disassembly (ARUP, 2022), meaning that current modern construction practice generates massive non-recyclable waste. The EU generates 374 million tons of construction and demolition waste annually (Eurostat, 2022), of which only 50% is effectively recycled. The green perspective demands that modern construction adopt the principles of separability and reuse that tradition practiced out of necessity.

The overall comparison between traditional and modern construction from a green perspective does not produce an absolute winner, but rather a matrix of complementary strengths. A multi-criteria analysis by Pacheco-Torgal and Jalali (2012), published in Construction and Building Materials and based on 6 indicators (embodied carbon, operational energy, durability, life cycle cost, circularity, and hygrothermal comfort), evaluated 8 construction systems and concluded that improved rammed earth with interior insulation achieves the best overall score (8.2/10) for single-family housing in a Mediterranean climate, followed by CLT timber with wood fiber insulation (7.8/10), brick masonry with ETICS (6.5/10), and reinforced concrete with XPS insulation (5.2/10). For high-rise buildings over 6 stories, the relationship partially reverses: CLT timber scores 7.5/10, steel with DfD 6.8/10, precast concrete 6.2/10, and reinforced earth 5.0/10 due to structural limitations.

The emerging trend is hybridization: buildings that combine recycled concrete foundations (modern structural module), load-bearing walls of rammed earth or stabilized CEB (traditional module), CLT floor slabs (modern bio-based module), and a green roof on timber support (traditional bioclimatic module). The CSIC pilot study MEDITARRE (2021), which built 3 prototype dwellings in Almería using this hybrid approach, documented embodied carbon of 125 kg CO₂eq/m² (65% lower than the conventional reference dwelling), operational energy consumption of 28 kWh/m²·year, and a construction cost of 1,050 EUR/m², only 8% higher than the conventional dwelling (970 EUR/m²). Considering the LCC over 50 years, the hybrid dwelling is 15% more economical due to lower energy consumption and maintenance. The green perspective indicates that the future of construction is neither traditional nor modern, but an intelligent integration that selects from each building tradition the solutions with the best verified environmental performance.