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example, after adding a wall assembly composed of brick cladding over metal studs,
the bill of materials reflects joint compound, mortar, nails, screws, and paper tape,
all of which were not specified by the user. In all programs, these additional materials are estimates of real-world conditions that more closely reflect how the building
will be constructed, but a WBLCA study will never be inclusive of every single
element used to actually build the building.
9.2.2 Structural System Comparison
The results of the initial WBLCA study, inclusive of fasteners and additional materials, were analyzed to find targeted areas of improvement within the project to
reduce impacts, specifically paying attention to GWP as this is the impact category
highlighted by the tools. The “Most contributing materials” section on One Click
LCA revealed that of cradle-to-gate (life cycle stages A1–A3) GWP, the two most
contributing materials are the “Steel roof and floor deck” and the “Steel, structural,
beams and columns.” They account for 36.1% and 24.1% of the impacts respectively. Looking at the results of the WBLCA study completed in Tally broken down
by material divisions, the metals division is the largest contributor to GWP over the
building’s life cycle at 33% of the total. When looking at the totals broken down
further by both division and Tally entry, the “Steel, W section (wide flange shape)”
alone accounts for 23% of the building’s GWP across the life span of the project.
Using these breakdowns of the WBLCA study, the building’s structural system is
a clear area to target improvements within the project design. A steel structural system was originally selected for the project to tie into the existing steel columns that
were salvaged. However, a second steel column was coupled with every existing
one to account for the additional loads of the two floors that were added to the project. Furthermore, steel beams and metal decking were added to support the new
floors. In the end, the majority of the structural system was new and was a big contributor across the impact categories. In this structural system comparison, the steel
system used in the original design was compared against a concrete structural system and a wooden structural system.
This study, over a 100-year service life, was inclusive of only structure, not foundations, envelope, or finishes. The original structural bay sizing, which is larger than
usual because it was designed for flexibility in a warehouse, was maintained in the
initial design as well as all structural systems tested. The steel system consists of the
salvaged steel columns matched with a new, secondary column and steel beams.
Spray fireproofing was added to all of the beams, and each column was encased by
two layers of gypsum board to meet required fireproofing. The floor system consists
of reinforced, cast-in-place concrete over metal deck. The concrete structural system consists of precast concrete columns and beams. The floor system consists of
precast hollow core concrete panels topped with a thin, reinforced layer of
9.2 Building 197
example, after adding a wall assembly composed of brick cladding over metal studs,
the bill of materials reflects joint compound, mortar, nails, screws, and paper tape,
all of which were not specified by the user. In all programs, these additional materials are estimates of real-world conditions that more closely reflect how the building
will be constructed, but a WBLCA study will never be inclusive of every single
element used to actually build the building.
9.2.2 Structural System Comparison
The results of the initial WBLCA study, inclusive of fasteners and additional materials, were analyzed to find targeted areas of improvement within the project to
reduce impacts, specifically paying attention to GWP as this is the impact category
highlighted by the tools. The “Most contributing materials” section on One Click
LCA revealed that of cradle-to-gate (life cycle stages A1–A3) GWP, the two most
contributing materials are the “Steel roof and floor deck” and the “Steel, structural,
beams and columns.” They account for 36.1% and 24.1% of the impacts respectively. Looking at the results of the WBLCA study completed in Tally broken down
by material divisions, the metals division is the largest contributor to GWP over the
building’s life cycle at 33% of the total. When looking at the totals broken down
further by both division and Tally entry, the “Steel, W section (wide flange shape)”
alone accounts for 23% of the building’s GWP across the life span of the project.
Using these breakdowns of the WBLCA study, the building’s structural system is
a clear area to target improvements within the project design. A steel structural system was originally selected for the project to tie into the existing steel columns that
were salvaged. However, a second steel column was coupled with every existing
one to account for the additional loads of the two floors that were added to the project. Furthermore, steel beams and metal decking were added to support the new
floors. In the end, the majority of the structural system was new and was a big contributor across the impact categories. In this structural system comparison, the steel
system used in the original design was compared against a concrete structural system and a wooden structural system.
This study, over a 100-year service life, was inclusive of only structure, not foundations, envelope, or finishes. The original structural bay sizing, which is larger than
usual because it was designed for flexibility in a warehouse, was maintained in the
initial design as well as all structural systems tested. The steel system consists of the
salvaged steel columns matched with a new, secondary column and steel beams.
Spray fireproofing was added to all of the beams, and each column was encased by
two layers of gypsum board to meet required fireproofing. The floor system consists
of reinforced, cast-in-place concrete over metal deck. The concrete structural system consists of precast concrete columns and beams. The floor system consists of
precast hollow core concrete panels topped with a thin, reinforced layer of
9.2 Building 197