Hi to all,
we would like to discuss a question about determining baseline and proposed building to meet LCA credit's requirements and meet the whole credits intent.
We work with the design team to set up the baseline and the entire approach to LCA credit. Our main question is - is the whole credit "only" a game of numbers and improvements to the proposed building so that it is better than the baseline, OR is it necessary to deal with REALLY built-in materials in the construction phase and compare this state (=built building) with the determined baseline?
I will give an example - we have a bill of quantities of the design-phase documentation of the object from which we created the LCA. We considered concrete reinforcement (steel rebar) with a small percentage of recycled components. By simply improving this percentage of recycled component from 60% to 90%, we have achieved more than 10% emission savings in LCA. But the question remains the same - is it necessary to prove that the construction actually used steel with a high proportion of recycled material, or is the whole credit a "paper-consideration" narrative?
The LCA credit is clasified as a construction credit, but there is no requirements for collectiong technical data sheets of really used materials in the building, so we are little bit confused about the credit's intent.
Thank you very much for your opinions and experiences.
Barbora Cicvarkova
(Skanska a.s., Sustainability consultant)
Henrique Mendonca
Life Cycle EngineereTool
2 thumbs up
May 25, 2020 - 10:48 am
Hi Barbora,
Although the baseline requirements are not clearly defined, it´s up to the LCA Author to define robust assumptions when necessary, reference project documentation and make it transparent in the report. When used early in the design, the credit will enable real gains but again the LCA Author needs to interpret the results and actual savings. Recycled content is steel is only a benefit becasue module D is not included. This article explains in more details. Another option is to integrate with available EPDs. I have found that expanding the scope to include all modules (beyond the credit requirements) often provides added value to the design team, to look at the whole building performance in one place (materials, energy, water, functionality), see how everything interacts, identify key impact areas and prioritise design improvements.
Regards,
Henrique
Bipin Karki
Project Manager - Sustainability Division84 thumbs up
May 27, 2020 - 8:27 am
Hello Barbora,
During ealry design, LCA Calculation is performed by the design team using Baseline and Proposed building. The proposed building materials are aniticapted ones. The main reason of doing LCA Calculation in design phase is to provide sufficient time for design team to find enviornmentally sustianble products/ materials or material design optimization. The design team will have enough time to make design changes or to find alternative materials for material optimization and envrionmental footprint reduction. The logic behind calculating in design phase is proper co-oridnation among LCA expert, Architect, and Contractors.
When the building goes in the construction, there are many cases the building materials/design case scenario changes. Based on the changes, the LCA calculation will have changes in the proposed building. The revised calculation and report based on this is documented and submitted for review. Thus, it is actually "necessary to deal with REALLY built-in materials in the construction phase and compare this state (=built building) with the determined baseline." That is the reason for this credit being Construction phase.
LCA Calculation is always encouraged in design phase, so project team can co-ordinate, educate, and make rational decision in initial phase. This is not just paper based consideration. You do not have to prove by providing bills of materials actually used in the construcion, but this is the intent behind this credit. There are several way for LCA calculation and optimization between baseline and proposed, which you can find online or within LEED Reference Guide.
Hope this helps!