186
In the case of a curtain wall door, the user is able to input information not included
in the Revit model related to the finish, hardware, hinges, and closer.
While all of these additional materials may seem inconsequential in the greater
WBLCA, the resultant sum of them adds up to make a material difference on the
results of the study. To show the impact these additional materials make on the
study, the WBLCA of Building 197 was completed twice in Tally, both with and
without the additional materials. Elements like rebar, spray fireproofing, window
and door hardware, or fasteners were the difference between the studies. The only
exception to this was in cases where the user was required to select an additional
material. For example, when assigning metal wall panels, Tally requires the user to
select a type of fastener, with no option to not include them in the study because
they are required in the built assembly.
Comparing the results of the two WBLCA shows between 18% and 30% decrease
in all impact categories without the additional materials (Table 9.1). These results
clearly demonstrate why it is important to understand what data is and is not
included in a BIM model as well as what the goal and scope of an assessment is.
Every decision made in completing a WBLCA study has the ability to appreciably
alter the results. This is why directly comparing two LCA studies carried out separated is not recommended. It is essential to maintain methodological consistency
between design option studies carried out by one person or team. Using the same
tools and methods for one project will maintain this internal project consistency.
The other WBLCA tools have their own ways of handling the gap between project data and real-world conditions. In the One Click LCA Revit plugin there is an
option for the user to add rebar to any concrete elements. Beyond this, information
on how the data point was collected and what it reflects can be seen in the EPD used
for the LCI data, if one was used. Athena does not interface with any outside programs and so is not drawing from any models. In every building assembly that the
user adds, Athena has additional information and materials related to building
assemblies that it automatically adds to the study. These additional materials, and
their quantities, can be seen in the bill of materials that Athena generates. For
Table 9.1 Comparison of LCA results for Building 197 with and without additional materials
in Tally
Tally-whole
Building LCA
WBLCA without
additional materials
Percent decrease
in impact
Global warming (kg CO 2 eq)
15,709,168
11,640,089
26%
Acidification (kg SO 2 eq)
81,719
56,822
30%
Eutrophication (kg Neq)
3164
2585
18%
Smog formation (kg O 3 eq)
917,372
688,883
25%
Ozone depletion (kg
CFC-11eq)
0.05
0.04
20%
Non-renewable energy (MJ)
242,532,107
197,241,102
19%
9 Case Studies
In the case of a curtain wall door, the user is able to input information not included
in the Revit model related to the finish, hardware, hinges, and closer.
While all of these additional materials may seem inconsequential in the greater
WBLCA, the resultant sum of them adds up to make a material difference on the
results of the study. To show the impact these additional materials make on the
study, the WBLCA of Building 197 was completed twice in Tally, both with and
without the additional materials. Elements like rebar, spray fireproofing, window
and door hardware, or fasteners were the difference between the studies. The only
exception to this was in cases where the user was required to select an additional
material. For example, when assigning metal wall panels, Tally requires the user to
select a type of fastener, with no option to not include them in the study because
they are required in the built assembly.
Comparing the results of the two WBLCA shows between 18% and 30% decrease
in all impact categories without the additional materials (Table 9.1). These results
clearly demonstrate why it is important to understand what data is and is not
included in a BIM model as well as what the goal and scope of an assessment is.
Every decision made in completing a WBLCA study has the ability to appreciably
alter the results. This is why directly comparing two LCA studies carried out separated is not recommended. It is essential to maintain methodological consistency
between design option studies carried out by one person or team. Using the same
tools and methods for one project will maintain this internal project consistency.
The other WBLCA tools have their own ways of handling the gap between project data and real-world conditions. In the One Click LCA Revit plugin there is an
option for the user to add rebar to any concrete elements. Beyond this, information
on how the data point was collected and what it reflects can be seen in the EPD used
for the LCI data, if one was used. Athena does not interface with any outside programs and so is not drawing from any models. In every building assembly that the
user adds, Athena has additional information and materials related to building
assemblies that it automatically adds to the study. These additional materials, and
their quantities, can be seen in the bill of materials that Athena generates. For
Table 9.1 Comparison of LCA results for Building 197 with and without additional materials
in Tally
Tally-whole
Building LCA
WBLCA without
additional materials
Percent decrease
in impact
Global warming (kg CO 2 eq)
15,709,168
11,640,089
26%
Acidification (kg SO 2 eq)
81,719
56,822
30%
Eutrophication (kg Neq)
3164
2585
18%
Smog formation (kg O 3 eq)
917,372
688,883
25%
Ozone depletion (kg
CFC-11eq)
0.05
0.04
20%
Non-renewable energy (MJ)
242,532,107
197,241,102
19%
9 Case Studies