METHODOLOGICAL DISCUSSION AND PILOTING OF LCA-BASED ENVIRONMENTAL INDICATORS FOR PRODUCT STAGE ASSESSMENT OF BRAZILIAN BUILDINGS

Resumo

The International Energy Agency (IEA)’s Annex 57 was established to advance on evaluation of embodied energy and GHG emissions for building construction. Its activities include recommendation of common calculation methods and disclosure of regional benchmarks. Process-based, input-output or hybrid life cycle assessment (LCA) can support such calculations. Identification of the major products that describe key building typologies plays a strategic role in the tasks of streamlining indicators’ monitoring scope and LCI data gathering in contexts with little LCA practice consolidation. Given these motivations and backdrops, our main goals are (i) to calculate a selected set of LCA-based indicators to synthetically describe environmental performance of construction products for three functionally equivalent case studies; (ii) to detect the major contributors to embodied energy (EE) and emissions (EGWP); and (iii) to examine the implications of considering embodied CO₂ versus total GHG emissions. The selected metrics include – besides EE and EGWP targeted by Annex 57 – the blue water footprint (bWF), non-renewable primary material consumption (NRc) and volatile organic compounds (VOC) emissions. Production cycle modeling used previously collected national data, as well as secondary data extracted from national and international literature or adapted from international databases whenever considered as reasonably similar to Brazilian processes. EE and EGWP results were calculated using the Cumulative Energy Demand (CED) method and the CML 2001 baseline v. 2.05 method, respectively, and are presented for the top contributing products. NRc, bWF and VOC calculations were directly derived from the inventories and discussed in more detail for cement and concrete. Around 80% of the total embodied energy was related to seven construction products, while four of them also responded for around 80% of embodied GWP. Enlarging the database to encompass ten core products would increase coverage to over 93%. For cement and concrete, partial replacement of clinker by ground granulated blast furnace slag brought substantial reductions in the calculated values for all indicators but bWF, which unveils the effect of the water-intensive granulation process. Further research is expected to advance in LCI development and validation to enable the use of life cycle-based metrics to support decision-making within the national building sector.