LCA Results – LEED Scope

The LCA credit for LEED has a reduced scope, it only covers the Life Cycle Modules (A1-A4, B1-B5, C1-C4) of the elements referring to the foundation, structure, envelope and roofing (Core and Structure). Although the certification is only looking at the commercial area, the LCA study includes the building as a whole, including the residential area, because it’s in the same structure.

In addition, the result of the study needs to demonstrate a reduction in the three indicator’s impacts, one of them must be the GWP (Global Warming Potential), the responsible impact for climate change.

Impact per square meter (m²)
(60 years)
BaselineFinal% reduction
Global Warming Potential
(kgCO2 eq)
4514138%
Eutrophication
(kg PO4 eq)
0.4890.4518%
Acidification of Land and Water Sources
(kgSO2 eq)
2.662.467%

The main improvements results of the embodied impact in the reduce of materials for LEED certification were:

  • Reuse of the existing retaining wall
  • Prestressed beams
  • Use of cement with 30% slag in concrete
  • Concrete transport nearby to the site
  • Reinforcement steel recycled content (Rebar).

Relevance of each implemented improvements:

Total tonne of CO2eqReduction tonne of CO2eq % reduction
Baseline (LEED)
26,308
Improvements
Reuse of the existing retaining wall255.180.97%
Prestressed instead of solid beams618.232.35%
Use of cement with 30% slag in concrete178.890.68%
Concrete transport nearby to the site86.820.33%
Reinforcement steel recycled content1,012.853.85%
Total reduction
2,1528%
Final (LEED)
24,156

This study was important to quantify the impact reduction of the improvements implemented by the project team and also as a reference for future projects, since the LCA was carried out with the work in progress. It is worth mentioning for future projects that LCA must be executed sooner, since in the conception project as for example, this way is a huge chance of reducing environmental impacts and also making improvements related to materials according to financial viability.

https://www.usgbc.org/projects/river-one-corporate

LCA also include Operation Impacts (Whole Life Cycle)

The LCA of the project realized was includes the embodied impacts of the foundation, structure, envelope, and roof materials following the LEED scope related to the construction phase, maintenance, and end of life, which in this case bringing it up the biggest impacts.

In addition, we found it necessary to also include in this study, the Whole Life Cycle or Whole Life Carbon to quantify the impacts related to energy consumption, supply, and water treatment as guided by the LCA standard EN 159781, with all stages of the Life Cycle (A1-A5, B1-B7, C1-C4 and D1-D5).

In this case, the impact of energy is bigger, followed by materials in the second, which consequently increased the impact of the entire project, as shown in the figure below (Impact Summary).

It is important to know which area of ​​impact is most relevant to know where and how to act on improvements in the the project’s design phase and thus have a significant reduction in impact at the lowest possible cost. Below are the quantified improvements for the Whole Life Carbon project including the reduction of emissions (CO2eq) and the percentage of reduction in relation to the total impact measured. This modeling has been done in a simpler way, without considering the installed systems and equipment. Only the reductions quantified were the energy consumption and water supply and treatment.

total tonne of CO2eq Reduction tonne of CO2eq% of reduction
Baseline (WLC) 48,58300
Improvements applied in the operational phase Energy Efficiency47,3221,2612.60%
Efficient Metals and Crockery46,9973250.67%
Automated Irrigation System46,956410.08%
Rainwater Harvesting and HVAC Condenser46,94790.02%
Structure Improvements Reuse of the existing retaining wall46,7072400.49%
Prestressed Beams46,1155921.22%
Use of cement with 30% slag in concrete45,8992170.45%
Concrete transport nearby to the site45,800980.20%
Reinforcement steel recycled content (Rebar)45,80000.00%
Final Project (WLC)45,8002,7835.73%

It is noted there was an increase in the impact when we include the consumption of water and energy in the project and the impact reduction is also small. These results are why all Life Cycle Stages have been seen (A-D). Even the improvement of steel, which had great relevance in the scope of LEED, here in Whole Life Carbon of LCA, when module D (recycling, reuse) is activated, the improvement of the recycled content of steel is not quantified because it comes from a closed chain. Follow the link with the complete explanation.

The purpose of this suggestion to use rebar with higher recycled content is to encourage manufacturers to reduce initial impacts at the product stage (A1-A3). This “benefit” is reported for the LEED scope only. LEED does not consider module D, which is the reuse of steel at the end of its life. Following the technical standard (EN15978), as steel is a closed-loop recycling material, the fact that it has a high recycled content does not interfere with the end result of the life cycle.

In addition, it is worth mentioning that the energy and water consumption of the building refers to the commercial building, whose area is 22,138 m².

  • Client: CTE, SDI Desenvolvimento Imobiliário and RBR Asset Management
  • Location: St. Gerivatiba, 207  Butantã – São Paulo SP – Brazil
  • Date: October 2019

This LCA study has been developed by Caio Alencar and certified by Henrique Mendonça from eTool.