El papel de la tecnología en la evaluación del ciclo de vida de los edificios

Life Cycle Assessment (LCA) of a building quantifies the environmental impacts associated with all life cycle stages according to standard EN 15978:2011: material production (modules A1-A3), transport to site (A4), construction (A5), maintenance and replacement during the service life (B1-B5), operational energy consumption (B6), operational water consumption (B7), demolition (C1), waste transport (C2), treatment (C3), and landfill (C4), plus benefits from reuse and recycling (D). One Click LCA (Bionova, Finland, annual license of 6,000-12,000 EUR) is the most widely used platform in the sector: its database contains more than 200,000 Environmental Product Declarations (EPDs) from 80 countries, compliant with EN 15804+A2, and automatically calculates the 7 mandatory impact indicators (GWP, ODP, AP, EP, POCP, ADPe, ADPf).

The Tally platform (Building Transparency / KieranTimberlake, USA) operates as a Revit plugin that extracts quantities directly from the BIM model and cross-references them with the GaBi database (Sphera, more than 15,000 records). Its key advantage is native integration with the BIM workflow: the architect or engineer can run a preliminary LCA in 2-4 hours on the design model without exporting data, obtaining results by building element (foundations, structure, envelope, partitions, services) and comparisons between design alternatives. In Germany, the eLCA tool (BBSR — Federal Institute for Research on Building, Urban Affairs and Spatial Development, free of charge) with the OEKOBAUDAT database (>1,300 generic construction material records) is the mandatory reference for the BNB (Bewertungssystem Nachhaltiges Bauen) certification of the German federal government, which requires a complete LCA for all public buildings with a budget exceeding 2 million EUR.

The integration between the BIM (Building Information Modeling) model and LCA tools represents the technological advancement with the greatest impact on the efficiency and reliability of building life cycle analysis. In the traditional manual workflow, the LCA analyst extracted measurements from the project documentation (typically in PDF or Excel format), manually entered them into the LCA tool, and assigned materials to environmental impact databases — a process that required 200-400 hours of professional work for a 5,000 m2 building and was subject to transcription errors estimated at 5-15% of total quantities (Cavalliere et al., 2019). BIM-LCA integration reduces this time to 20-60 hours and virtually eliminates quantification errors by automatically extracting volumes, areas, and masses from each element in the model.

The operational integration workflows in 2024 are: (1) Revit to One Click LCA via native plugin that extracts material quantities by Revit category (walls, floors, roofs, columns, beams), with semi-automatic assignment to specific EPDs or generic data, total process of 4-8 hours for a well-defined model; (2) Revit to Tally via integrated plugin that runs the LCA within the Revit environment itself in 2-4 hours; (3) IFC to One Click LCA via import of the model in open IFC 4.0 format, compatible with ArchiCAD, Vectorworks, Allplan, and other BIM software; (4) Excel to eLCA for the German market, with standardized templates that map cost model items per DIN 276 to the OEKOBAUDAT database. The research by Wastiels and Decuypere (2019) demonstrated that BIM-LCA integration reduces inter-analyst variability (the same building assessed by different professionals) from 25-40% in the manual method to 8-12% in the automated method, significantly increasing the reproducibility and comparability of results.

The calculation of whole-life carbon (WLC) integrates embodied carbon (modules A1-A5 + B4 + C1-C4) and operational carbon (module B6) into a single indicator over a Reference Study Period (RSP) typically of 50-60 years. The relative proportion between these two components has undergone a historic inversion: in 1990s buildings, operational carbon represented 75-85% of WLC and embodied carbon 15-25%; in current NZEB buildings with high-performance envelopes and renewable sources, embodied carbon represents 50-70% of WLC (Rock et al., 2020), making material selection the decision with the greatest impact on the total carbon footprint.

Technological LCA platforms enable quantitative comparisons between construction alternatives that guide design decisions toward decarbonization. A typical analysis using One Click LCA for a 5,000 m2, 5-story office building compares: (1) reinforced concrete structure — embodied carbon of 350-450 kg CO2eq/m2 (A1-A5); (2) steel structure — embodied carbon of 280-380 kg CO2eq/m2; (3) cross-laminated timber (CLT) structure — embodied carbon of 150-250 kg CO2eq/m2, with biogenic carbon storage of -80 to -120 kg CO2eq/m2. The RIBA 2030 Climate Challenge benchmark sets embodied carbon targets of 300 kg CO2eq/m2 for 2030 and 200 kg CO2eq/m2 for 2040 (residential: 350 and 250 respectively), values that are only achievable through the combination of technological LCA tools to identify optimal reduction strategies and low-footprint materials verified with EPDs.

The European Commission's Level(s) framework (version 2.0, 2021) establishes 6 macro-objectives and 16 indicators for assessing building sustainability, with Indicator 1.2 (Life cycle Global Warming Potential) being the most relevant for LCA: it requires calculating GWP in kg CO2eq/m2 per year for modules A1-A3, B4, B6, and C3-C4, with the building's RSP. Level(s) is not a certification system but a voluntary reporting framework; however, its integration into European public procurement award criteria through Directive 2014/24/EU and Green Public Procurement (GPP) criteria makes it a de facto requirement for projects financed with European funds. The revised EPBD (2024) requires that from 2027, the life cycle GWP (Level(s) indicator 1.2) be calculated and disclosed for all new buildings larger than 2,000 m2, and from 2030 for all new buildings without exception.

The DGNB (Deutsche Gesellschaft fur Nachhaltiges Bauen) certification system has been a pioneer in integrating LCA as a mandatory and determining criterion: criterion ENV 1.1 (Life Cycle Assessment) carries a weight of 9.5% of the total score (the highest individual weight of any criterion), requires complete calculation of modules A1-A3, B4, B6, and C3-C4, and establishes reference benchmarks by typology — offices: 9.4 kg CO2eq/m2 per year (reference value), 6.5 kg CO2eq/m2 per year (Platinum target). In France, RE2020 (Reglementation Environnementale 2020, in force since January 2022) was the first mandatory regulation in the world to set maximum embodied carbon limits for new buildings: 640 kg CO2eq/m2 for housing (modules A1-A4) in 2022, with progressive reduction to 415 kg CO2eq/m2 by 2031. This accelerated regulatory tightening ensures that technological LCA tools — currently used voluntarily in 15-20% of projects in the EU (BPIE, 2023) — will become mandatory for 100% of new buildings before 2030, transforming LCA from a competitive advantage into a basic requirement of professional practice.