Normativas emergentes en construcción verde. Casos de éxito

First-generation sustainable construction regulations (2002-2018) focused almost exclusively on operational energy performance: the European EPBD (2002), the Spanish CTE (2006), and the American ASHRAE 90.1 standard regulated insulation, HVAC system efficiency, and renewable contribution, but ignored the emissions generated during material manufacturing, transportation, and construction (phases A1-A5 per EN 15978), which represent between 20% and 50% of the total life cycle impact of a new building (Röck et al., 2020). As buildings become more operationally efficient (an nZEB building consumes 15-30 kWh/m²·year for heating compared to 100-200 kWh/m²·year for the existing stock), the relative weight of embodied carbon increases: in a new construction building that complies with the recast EPBD (2024), material manufacturing emissions represent 45-65% of total emissions over a 50-year service life (World Green Building Council, 2019). This realization has driven a new generation of regulations that govern the building's complete life cycle, from raw material extraction to demolition and waste treatment.

The European Commission's Level(s) framework, published in 2020 as a voluntary tool and intended as a basis for future regulatory requirements, defines 6 measurable macro-objectives: life cycle GHG emissions (kg CO₂eq/m²·year), efficient resource use and circular economy, efficient water use, occupant health and comfort, climate change adaptation, and life cycle cost. The Level(s) life cycle emissions indicator follows the EN 15978 standard and covers phases A1-A5, B1-B7, and C1-C4, with an optional phase D for reuse and recycling benefits. The Commission estimates that widespread application of Level(s) as a regulatory basis would reduce life cycle emissions of new buildings in the EU by 30% to 40% by 2030 compared to current practices. The recast EPBD (2024) requires for the first time that member states calculate the global warming potential of the life cycle of new buildings larger than 1,000 m² from 2028 and of all new buildings from 2030, laying the groundwork for future mandatory emission limits.

The Réglementation Environnementale 2020 (RE2020), in force since January 2022, is the first national regulation in the world to combine operational energy performance requirements, summer comfort, and embodied carbon limits in a single mandatory framework for all new construction. Key requirements include: maximum heating demand of 12 kWh/m²·year for collective housing in zone H1 (northern France), maximum primary energy consumption of 70-90 kWh/m²·year depending on climate zone, and an embodied carbon emissions limit for materials (ICénergie indicator) of 640 kg CO₂eq/m² of habitable floor area for collective housing, decreasing to 530 kg CO₂eq/m² in 2025, 415 kg CO₂eq/m² in 2028, and 260 kg CO₂eq/m² in 2031 (Ministère de la Transition Écologique, 2021). The ICconstruction indicator covers emissions from phases A1-A5, B1-B5, and C1-C4 over a 50-year service life for housing and 50 years for commercial buildings.

The first results of the RE2020 after two years of implementation show quantifiable transformations in the French market. The market share of structural timber in collective housing increased from 4% in 2021 to 12% in 2023 (Codifab, 2024), driven by the lower embodied emissions of wood (-30 to -50 kg CO₂eq/m³ considering biogenic capture) compared to concrete (+250-400 kg CO₂eq/m³). Low-carbon concrete (using CEM III cements with blast furnace slag or CEM V with fly ash and limestone) reached 28% of the French market in 2023 versus 8% in 2021 (SFIC, 2024). The average cost premium of the RE2020 compared to the previous RT2012 standard is estimated at 3-8% for collective housing and 5-12% for single-family housing (CEREMA, 2023), but the industry is progressively absorbing this premium through innovation and economies of scale. A study by Carbone 4 (2023) on 120 RE2020 projects found that 35% already met the 2025 thresholds and 8% the 2028 thresholds, demonstrating that the regulatory trajectory is technically achievable with existing technologies.

Denmark introduced in 2023 a mandatory limit of 12 kg CO₂eq/m²·year of life cycle emissions (phases A1-C4, 50 years) for all new buildings larger than 1,000 m², decreasing to 10.5 kg CO₂eq/m²·year in 2025 and 7.5 kg CO₂eq/m²·year in 2029 (Boligministeriet, 2022). This progressive threshold requires a 37.5% reduction in life cycle emissions over 6 years. The calculation is performed using the LCAbyg tool, developed by BUILD (Aalborg University), which integrates a database of 1,200 materials with EPDs specific to the Danish market. The first 350 projects evaluated under the new regulation show average emissions of 9.8 kg CO₂eq/m²·year for housing and 11.2 kg CO₂eq/m²·year for offices, with an average reduction of 25% compared to equivalent projects from 2020 (BUILD, 2024). The most effective strategies were: substitution of conventional concrete with low-carbon concrete (-18% emissions), use of structural CLT timber (-25%), elimination of underground parking (-12%), and optimization of structural thickness through parametric design (-8%).

The Netherlands implemented in 2018 the Environmental Performance of Buildings Regulation (MPG), which requires a maximum environmental impact of 0.8 points/m²·year calculated using the national MilieuPrestatie Gebouwen tool, based on 11 weighted impact categories following the CML methodology. The limit decreases to 0.5 points/m²·year in 2025. In the United States, the federal Buy Clean Act (included in the Inflation Reduction Act of 2022) establishes emission limits for construction materials purchased with federal funds: concrete, steel, glass, and insulation must present EPDs and meet emission thresholds set at the 75th percentile of the national market, implying a minimum reduction of 25% compared to the average. California implemented its own Buy Clean Act in 2017, the first at the state level, applicable to structural steel, flat glass, and mineral insulation, with limits that have reduced the average emissions of materials purchased by the state by 20% over 5 years (California DGS, 2023). These regulatory frameworks are converging toward a global standard of environmental transparency based on verified EPDs and declining embodied carbon limits.

Embodied carbon regulations are transforming construction material supply chains. The European cement industry, responsible for 7% of global CO₂ emissions, has accelerated the transition toward low-clinker cements: the average clinker-to-cement ratio in the EU dropped from 76% in 2017 to 71% in 2023 (CEMBUREAU, 2024), and companies such as Heidelberg Materials, Holcim, and CEMEX market cements with a carbon footprint 30-50% lower than conventional CEM I Portland. The steel sector is investing in green steel production with hydrogen: the HYBRIT plant of SSAB in Sweden produced the first tons of steel in 2021 with emissions of 0.05 tCO₂/t compared to 1.85 tCO₂/t from the conventional blast furnace process, a reduction of 97%. ArcelorMittal has committed 10 billion EUR in investment to decarbonize its European production by 2030, with the goal of reducing emissions by 35% compared to 2018. Third-party verified EPDs have multiplied: the European ECO Platform database records 12,500 active EPDs in 2024, up from 3,200 in 2018, a growth of 290%.

Spain still lacks mandatory embodied carbon regulation. The CTE-DB HE (2019) regulates operational energy consumption but not material emissions, and the Level(s) framework is used only voluntarily in projects financed with European funds. The roadmap toward regulation equivalent to the French RE2020 or the Danish standard requires: developing a national database of emission factors for construction materials (currently scattered between the ITEC Cost Database and generic Ecoinvent data), establishing an official LCA calculation tool validated by the Ministry of Transport, and defining a trajectory of progressive emission limits for 2028-2035. The GBCe estimated in 2023 that the average life cycle emissions of a new residential building in Spain stand at 14-18 kg CO₂eq/m²·year (phases A-C, 50 years), a value 40-80% higher than the Danish 2029 target (7.5 kg CO₂eq/m²·year). Reaching comparable levels would require a combination of low-carbon concretes (-30%), hybrid timber-concrete structures (-20%), reduction of structural over-dimensioning (-10%), and reuse of reclaimed materials (-5 to -10%), all accompanied by a training program for 5,000 professionals in building LCA.