Material eco-efficiency indicators for Brazilian buildings

The purpose of this paper is to propose a set of lifecycle-based indicators to describe material eco-efficiency of buildings normalized per unit of gross floor area (GFA), and at verifying feasibility of their calculation for building materials and components, based upon four case studies. The paper also examines the effects that discrepancies between two carbon footprint accounting methods (embodied CO₂ (ECO₂) vs embodied CO_2e) have on communication of environmental performance of selected materials.

The lifecycle assessments (LCAs) were performed through LCA support platform SimaPro 7.3. Data for materials/components production cycle modeling were collected from primary and secondary data from national literature or adapted from Ecoinvent database. Embodied energy, ECO₂, blue water footprint (bWF), non-renewable content and volatile organic compound emissions (VOCe) indicators were calculated from lifecycle inventory (LCI) outputs, while embodied CO_2e was calculated using CML 2001 v.2.01 impact assessment method.

Obtained results suggest that a core database comprised of 12 materials and components – cement, ceramic blocks, steel rebar, sawn timber planks, PVC tubes, plywood, PVC conduits, roof steel structure, roundwood, ceramic tiles, hydrated lime and adhesive mortar – provides a very reasonable description of a building's embodied energy (99.63 percent), embodied CO_2e (97.50 percent), bWF (96.26 percent), non-renewable content (97.53 percent) and VOCe (95.38 percent) profiles. Except for bWF of cement and concrete, substantial reductions in the metrics’ values captured environmental advantages of partially substituting ground granulated blast furnace slag (ggbs) for clinker Portland.

The disclosure of embodied energy and carbon, as well as of other environmental performance data at whole-building level (per unit of GFA) pointed out in this paper, allows comparability and helps to establish performance goals and benchmarks and to guide policy decisions. Following a coordinated methodological outline, future works are expected to evolve to gradually constitute a LCI database that enables the use of the proposed metrics and of LCA as decision-making tools in the building sector.