Content uploaded by Christoph Gengnagel
Author content
All content in this area was uploaded by Christoph Gengnagel on Aug 28, 2021
Content may be subject to copyright.
SimAUD 2021 April 15-17
A Holistic and Parametric Approach for Life Cycle
Assessment in the Early Design Stages
Diego Apellániz1, Panu Pasanen2, Christoph Gengnagel1
1
B+G Ingenieure Bollinger und Grohmann GmbH
Universität der Künste Berlin
Berlin, Germany
{dapellaniz, cgengnagel}@bollinger
-
grohmann.de
2
Bionova Ltd.
Helsinki, Finland
panu.pasanen@bionova.fi
ABSTRACT
This paper presents an approach for implementing life-cycle
assessment (LCA) in the early design stages of a building
project based on the new plugins for Rhino and Grasshopper
of One Click LCA, which aims to contribute to fight climate
change from within the construction industry. These new
tools developed by Bollinger + Grohmann in collaboration
with Bionova Ltd. combine the extensive environmental
database of One Click LCA with a user-friendly interface
and an object-oriented structure to provide parametric and
holistic LCA within the environment Rhino + Grasshopper.
A case-study of the implementation of this tool in the design
phase of an office building complex in Berlin is also included
to illustrate new possible workflows in the early design
stages regarding comparison of embodied energy of design
alternatives, automatic LCA from architectural and
calculation models, optimization processes based on global
warming potential (GWP) and environmental benchmarking.
Author Keywords
Life-cycle assessment; sustainability; parametric design;
optimization; object-oriented programming.
1 INTRODUCTION
1.1 Climate emergency and shortage of resources
With more than 30 % of global carbon dioxide emissions, the
construction and building materials sector is the biggest
driver of global climate change [1]. The current world
climate report of the International Panel on Climate Change
(IPCC) underlines the absolute necessity for an immediate
rethink and the readiness to implement existing solutions in
the short term. The goal of this radical change is a drastic
reduction of the grey energy contained in new buildings and
the associated reduction of CO2 emissions. At the same time,
the enormous resource consumption of current construction,
especially in the area of mineral materials [2], requires a
rediscovery of material-saving construction that is oriented
towards the basic concepts of material effectiveness,
robustness, structural diversity and the use of local resources.
The use of materials based on renewable raw materials
should be a priority.
1.2 Life-cycle assessment in the early design stages
In order to effectively fight climate change from within the
construction industry, an adequate metric must be
implemented from the very beginning of the design stage to
positively affect the environmental outcome of a
construction project. Life-cycle assessment (LCA) is
arguably the most extended objective methodology for
evaluating the environmental impact of products, processes
and services which can also be applied to evaluate the
environmental impact of a certain building [3].
However, the LCA of such a complex product as an actual
building presents some major challenges [4]. Firstly,
environmental information of all materials and processes
involved must be gathered. This data is quantified in the so-
called environmental product declarations (EPD). Secondly,
all material quantities must be measured and processes must
be covered to properly assess the environmental impact of
the whole building over its lifetime.
The current approach to the LCA of buildings usually
involves gathering the relevant data of the EPDs of the
different materials in an Excel file or similar database to
combine these values with also manually introduced material
quantities, but unsurprisingly this analogic and time-
consuming workflow tends to discourage designers from
applying LCA. The use of Building Information Modelling
(BIM) can help automating the generation of the bill of
quantities of the building, including at times also mapping
the EPD values to the corresponding building materials [5],
but a complete and ready to use BIM model is usually not
available until the late design stages, when there is
unfortunately no much potential for further design changes.
Alternatively, LCA can also be implemented and automated
in a certain design software tool. There are various software
packages designers use in the architectural practice, but the
most preferred option when parametric design is involved is
clearly Rhinoceros + Grasshopper3d [6].
1.3 Review of existing tools
According to food4rhino.com, “Tortuga” is the most
downloaded tool for LCA in the environment Rhino +
Grasshopper. Although this Grasshopper plugin offers an
intuitive interface and output of results, its EPD database is
constrained to the German ÖKOBAUDAT and the last
update of the tool took place four years ago [7].
Another available plugin in food4rhino.com is “Bombyx”
[8]. This is an exhaustive tool for LCA which also calculates
operational energy. However, the EPD database is strongly
focused on Swiss materials and also the not object-oriented
structure of the plugin leads to a not very user-friendly
experience when dealing with all input and output
parameters of the different components.
Finally, the last widely used LCA tool in Rhino +
Grasshopper might be the implementation of the commercial
software CAALA [9]. Although the web platform provides
the designer with an exhaustive and yet flexible LCA tool,
the EPD database is also constrained to ÖKOBAUDAT and,
furthermore, the Grasshopper plugin consists currently of a
single component for merely exporting material quantities
from a Rhino model to their web application, without
importing LCA results back into Grasshopper, which
provides no option for analysis or visualization of results in
Grasshopper, let alone for parametric optimizations.
2 METHODOLOGY
On the basis of this review, the authors found the necessity
to develop a new plugin for Rhino and Grasshopper that
overcomes the previously commented shortcomings at
implementing LCA in the early design stages of a building
project. This new development would need to:
Include an extensive materials EPD database,
covering a significant range of countries.
Support both structural and non-structural materials
so that the tool can be holistically used to assess the
environmental impact of a whole building.
Allow both simplified and complete LCA.
Return results of LCA in Rhino + Grasshopper for
their analysis and visualization and also for
allowing building optimizations regarding
embodied carbon.
Provide an user-friendly experience for both basic
and advanced Rhino and Grasshopper users to
encourage LCA in the design phase.
Due to its compliance with the above-mentioned criteria and
a demonstrated interoperability with other software such as
Autodesk Revit, One Click LCA was the preferred LCA
software to implement in the environment Rhino +
Grasshopper.
2.1 One Click LCA
One Click LCA is a commercial automated life-cycle
assessment software focused on calculating embodied
carbon or life-cycle assessment of building and infrastructure
projects. It includes the world’s largest materials EPD
database in this field and it is offered as a cloud service [10].
Furthermore, it is complemented by an API which includes
many of its functionalities, so third-party applications can set
up and run a LCA from their own user interface (UI). The
API of One Click LCA has been already implemented in
plugins for applications such as Autodesk Revit and it will
be used for this implementation in Rhino and Grasshopper as
well.
Although not all the functionalities of One Click LCA are
included in the API, it includes a method for exporting
material data into their web platform to run the LCA there
and access all functionalities such as input materials
verifications, advanced LCA, graphic analysis of results or
embodied energy comparison with benchmark projects [11].
2.2 Plugin for Rhino
The plugin for Rhino is particularly intended for designers
who might not be advanced users of the parametric
environment, but can anyway benefit from a geometrical 3D
model to automate estimation of material quantities for a
LCA. This tool does not only accomplish this, but it also
provides functionalities for mapping material environmental
profiles, including EPDs, to the geometric objects of the
Rhino model by grouping them according to their
corresponding model layer and also by implementing certain
filter options related to the material properties of the EPD
database. The final step is to export the list of materials to the
cloud service of One Click LCA through the API.
All the plugin functionalities are packed inside of the tabs of
a dockable Graphical User Interface (GUI) which lead the
users through different steps to run a LCA:
Materials: An overview of all geometry objects of
the considered layers is provided so that the user can
choose to manually map these objects to certain
resources by using the filter options, by picking a
material from the database, by manually specifying
a material description or just to leave the material
field empty to assign it later in the web platform.
Layers: Selection of the layers whose objects must
be considered in the LCA with the possibility of
later mapping all the layer objects to different
materials or to the same one. Layer names are used
to define the groupings used for the LCA, and each
material is assigned to one of the groups.
Settings: Choice of master materials database
(Europe, US, ÖKOBAUDAT, INIES, etc.) and
specification of building area for later calculation of
relative embodied carbon and benchmarking. In
order to retrieve the environmental impact results
from the server into the Rhino model, it is necessary
to log in into One Click LCA from this tab.
Results: An overview of the mapped materials and
the environmental results retrieved from the One
Click LCA server is provided.
Figure 1. UI of the Plugin for Rhino of One Click LCA.
Besides the tab functionalities, the GUI also contains a
toolbar with the following commands:
LCA in Cloud: Materials can be exported at any
time from the Rhino Model to run the LCA in the
web application of One Click LCA.
Refresh: Environmental data of the Results tab are
updated.
Reset: All fields are reset to the default values.
Help: Link to the help documentation site.
2.3
Plugin for Grasshopper
Unlike the One Click LCA plugin for Rhino, in which
similarly to CAALA [9] not all the geometric objects that
make up the LCA need to be mapped inside of Rhino, the
Grasshopper plugin requires the user to parametrically map
all building components to LCA profiles. This is a similar
approach to the Tortuga [7] and Bombyx [8] plugins and it is
required for optimization processes in which the result of the
LCA in terms of global warming potential (GWP) must be
calculated inside of the Grasshopper script.
Therefore, the plugin for Grasshopper of One Click LCA is
intended for rather intermediate and advanced users of this
visual programming environment who are willing to take
more time setting up the LCA inside of Grasshopper to
parametrically explore the environmental outcome of
different design alternatives, optimize a design proposal in
terms of GWP or embodied carbon or just make use of the
visualization options that this plugin offers. Because of this,
in terms of simple calculations of LCA or embodied carbon,
the Rhino plugin achieves the first set of results faster.
In order to populate the plugin with user-friendly
Grasshopper components, an object-oriented structure must
be defined so that the user just needs to manage individual
LCA objects instead of the properties of all of them which
would result in an unnecessarily complex Grasshopper
definition. The following classes were defined for this
purpose:
LCA Profile: To be selected from the database of
One Click LCA. It has properties regarding material
type, EPD database, corresponding country or
region, etc. to make it possible to filter these objects
within the database and select the desired one.
Material: It is constructed by assigning an LCA
Profile to a certain building element so it also has
properties regarding quantity and units.
Construction: These are the objects that are actually
fed into the LCA. They can consist of several
Materials, they have a class assigned to them so
they can be grouped during the LCA and they
include environmental results once the LCA is
completed.
Figure 2. Workflow diagram of a LCA with the Grasshopper plugin of One Click LCA.
The plugin components were compiled using the same GUI
widgets as the Karamba plugin [12] (see Figures 3 and 5).
They provide Grasshopper components with additional
functionalities such as extendable menus, dropdown lists,
checkboxes, etc. and are ideal to manage objects with
multiple properties in the Grasshopper environment. Also,
tooltips were implemented to select LCA Profiles with
particularly long names from the dropdown menus of the
“Select LCA Profile” component.
The “Calculate LCA” component has two outputs. The first
one includes all the Constructions with environmental results
so that they can be analyzed either graphically with the
“Visualize Results” component or numerically with the
“Disassemble” components. The second output provides the
numerical result of the embodied carbon of the building (kg
CO2-equivalent emissions). These results make reference to
the stages A1-A3 (manufacture stage) of a life cycle analysis
[13]. If a more thorough LCA was, the user should choose
the option “LCA in Cloud” to import the Constructions to the
web platform of One Click LCA similarly to the Rhino
plugin and calculate the LCA there.
Figure 3. Results visualization of LCA with the “Visualize
Results” component of the Grasshopper plugin of One Click LCA.
The numeric output of the “Run LCA” component can be
perfectly used for building optimizations targeting the
minimization of the environmental impact. The return of first
environmental results from the server takes usually a few
seconds, however, the plugin implements a cache so results
of previous calculations are saved and the connection with
the server is just necessary when constructions with new
LCA profiles are provided. If the results are obtained from
the cache, this usually takes no more than some milliseconds,
which makes this plugin optimal for such optimization
processes (see Figure 8).
2.4
Case Study Description
In order to further test the plugins and to evaluate to what
extent they can enhance the design process, they were used
in the design phase of an office project (Berlin, Germany)
designed by the architectural team of Thomas Hillig
Architekten GmbH and Bollinger + Grohmann as structural
engineers.
Figure 4. Aerial render of the office complex in Berlin, Germany
© Thomas Hillig Architekten GmbH.
The case study will focus on House B which is planned as a
flexible office building with adaptive service units. The
building consists of a multi-level structure with a maximum
of eleven floors. Thus, the entire building is subject to the
building code requirements of a low-rise building. The
dimensions on the lower floors (ground floor to 2nd floor)
are approx. 41m x 60m and are reduced to approx. 32m x
34m on the top floors (8th to 10th floor). Since there was no
major constraint from the architectural or engineering point
of view regarding the usability of concrete, steel or timber,
this project was the perfect case-study to test the potential
of these tools to positively influence the environmental
impact from the early design stages.
3
RESULTS
The One Click LCA plugins were used throughout the design
phase of the project by the structural design team of
Bollinger + Grohmann. This section shows one of many
possible design approaches and they can also be applied by
other specialist teams involved in building design.
3.1
Comparison and evaluation of design alternatives
Firstly, the Grasshopper plugin was used to compare and
optimize different design alternatives. A representative and
manageable local model of the building was used for this
purpose (see Figures 8 and 10), so different design
possibilities could be effortlessly explored without
modelling and analyzing the whole building. The use of a
Grasshopper definition for the calculation of the LCA has the
advantage that the designer needs to set up the Grasshopper
definition for the first design alternative and it can be easily
adapted for the other ones [14] without the necessity of
defining the LCA from scratch several times.
During the design exploration process, it was noticed that the
selection of a certain material for a particular building
element affects the building embodied carbon in different
ways. Obviously, different building materials possess
different GWP values (kg CO2e / kg), e.g. steel materials
usually present higher values than cross laminated timber
(CLT) ones [15]. However, there are some additional
considerations to take into account:
Building elements such as beams, slabs, etc. must
be dimensioned accordingly to the chosen building
materials in order to accurately calculate the
absolute impact of the system [15]. If the steel
members turn out to be relatively much smaller than
the timber ones for a certain design situation, the
timber solution might not be the one that results in
the lowest environmental impact. Furthermore,
changes regarding building materials of certain
building elements like structural beams can
influence the sizing of neighbor elements such as
columns or foundation elements due to the new
design loads, connection requirements, etc.
Structural elements of different building materials
imply the use of different types and quantities of
non-structural materials. For instance, a concrete
slab has different requirements in terms of noise
insulation and fire protection than a timber one.
Since data regarding non-structural elements might
not be available from the very beginning of the
design phase, assumptions are necessary in order to
properly evaluate the environmental impact of a
particular solution [16]. The database of One Click
LCA includes assemblies (see Figure 5) consisting
of different single structural and non-structural
materials that simplify this holistic design
comparison process. Otherwise, it is encouraged to
set up a library of standard Constructions in the
Grasshopper plugin consisting of the structural and
the corresponding non-structural materials in order
to efficiently compare different design alternatives.
Figure 5. Systems and assemblies of the database combine
different structural and non-structural materials.
Three different slab systems were compared in the design
phase. It will be shown that the horizontal elements
concentrate most part of the embodied carbon (see Figure 7,
also [17]). Furthermore, the also relevant interior walls were
designed as reinforced concrete elements due to fire
protection and lateral stability requirements. Therefore, the
comparative study focused on the slab and beam elements:
System 1: Closely spaced 50x110 CLT primary
beams and 20x110 CLT secondary beams and
slender 10 cm thick CLT panels.
System 2: Widely spaced 12x60 laminated veneer
lumber (LVL) beams and 22 cm thick CLT panels.
System 3: Traditional steel construction with IPE
profiles and sandwich slab panels. Used to quantify
the expected impact reduction of the timber systems
[18].
Once all building elements were dimensioned, the models
were exported to the web platform of One Click LCA with
the “LCA in Cloud” option for further analysis and
comparison. Some of the available graphical results are
displayed in Figures 6 and 7.
Figure 6. Comparison of impact results of the different
design alternatives with the web platform of One Click LCA
.
Figure 7. Distribution of embodied carbon among the different building elements
.
The results summary of Figure 6
shows
that the timber-based
solutions present lower embodied carbon than the
conventional steel floor system. Moreover, Figure 6 shows
the Bio-CO2 storage regarding the CO2 sequestrated by the
timber solutions, which can arguably be subtracted from the
overall CO2 result [19].
However, it must be noticed that the results also include the
impact values of walls and columns, which are identical in
all systems (see Figure 7), in order to make it possible to
compare the absolute impact values with other benchmark
projects. Among the two first timber systems, the “System
1” with the close spaced CLT beams results in the lower
embodied carbon. This might not only be related to the
different embodied carbon values of CLT and LVL, but also
to the fact that the thickness of the relatively structurally
inefficient slab element was minimized to 10 cm by
providing secondary CLT beam elements [20].
On the basis of the results of this representative local
model, the “System 1” was chosen to design the rest of the
building accordingly.
3.2
Integration with other Grasshopper Plugins for
multi-criteria optimization
The plugin for One Click LCA can be integrated in the same
Grasshopper script as other plugins, which might not be
directly related to LCA, in order to couple the analysis of
CO2 emissions with other criteria. In this section, the focus
will be on the optimization of the discussed office building
in terms of both embodied carbon and structural
performance.
Karamba
Regarding the optimization of structural systems with one
single building material, the solution resulting in lower
embodied carbon will be the one with the minimum amount
of material and these optimization processes have already
been extensively reviewed and improved [21]. However,
regarding structural systems with different materials, the
solution with lowest embodied carbon might differ from the
most economical one. Such optimization processes have
already been formulated, but they usually involve importing
environmental data into Grasshopper either manually or
through Excel sheets [22]. The Grasshopper plugin of One
Click LCA enhances this process by integrating the material
selection in a single component in Grasshopper. The
dimensions of the CLT and LVL element of the “System 2”
of this study of design alternatives were determined by
setting up an optimization process with Karamba [12] and
Galapagos [23] that would lead to the lowest embodied
carbon also under consideration of the code regulations in
terms of allowable deformation values.
Figure 8. Minimization of building embodied energy with
Karamba, Galapagos and the Grasshopper plugin of
One Click LCA
.
The evolutionary solver of Galapagos takes as genes the
height values of the slab and beam elements and the CO2
emissions serve as fitness function to be minimized. A
penalization value is added to this function if the slab
deformations overcome a certain limit value.
Octopus
The above-mentioned optimization of the structural system
of the office building in terms of embodied energy led to a
solution based on a thin slab supported by relatively strong
end efficient beam elements. However, it was necessary to
evaluate the actual economic cost of these design options in
parallel with the embodied energy.
Figure 9. Multi-objective optimization with Octopus and One
Click LCA
.
The plugin octopus was used for this purpose [24]. It
provides a multi-objective optimization solver, which was
used to simultaneously optimize the dimensions of the
structural system in terms of carbon emissions, economic
cost and structural performance.
The result is a Pareto front or set of optimal solutions (see
Figure 9), from which the user can choose the most
convenient one. It can be noticed how many different
solutions are contained in the plane “price-displacement”
which present a very low value of embodied energy but vary
enormously in terms of the other two parameters.
Parametric FEM Toolbox
As the deign process progresses, the final dimensioning of
the different building components usually takes place within
a structural design software package, where the designer
explores different configuration options for the different
building elements, until an economical solution that also
fulfills the code regulations is reached. In this context, the
Grasshopper plugin of One Click LCA and the Parametric
FEM Toolbox [25] were used to set up a connection between
the FEM program Dlubal RFEM and Grasshopper in order
to estimate in real time the environmental impact of different
design alternatives.
Figure 10. Real time environmental impact analysis from a
structural calculation model with the
Parametric FEM Toolbox
and the Grasshopper plugin of One Click LCA.
3.3
Global LCA and comparison with benchmarks
Once all the structural and non-structural elements had been
defined at the end of the concept design phase, a global
architectural 3D model including non-structural elements,
such as partition walls and facade elements, was used to run
the LCA of the whole building and compare it to benchmark
values. If a coherent layer structure is used for the
architectural 3D model, the pre-processing time for the LCA
can be significantly reduced due to the automatic grouping
and mapping functionality of the Rhino plugin.
Figure 11. Rhino 3d model of the office building for LCA
.
The LCA and the comparison with similar benchmark
projects showed good results in terms of embodied carbon,
therefore the design phase was considered satisfactory and
little further optimization of building elements regarding
sustainability concepts was done. Furthermore, the required
time for setting up and running the LCA from the already
available Rhino model for a user already familiar with the
tools took less than 30 minutes, which is significantly lower
than what similar experiments have shown [9].
Figure 12. Embodied
carbon benchmark
of the office building
.
The focus of this case-study was the applicability of LCA in
early design stages. In case that a more thorough LCA was
to be done in the later detailed design phase using a BIM
Model as the source for material quantities, the already
available environmental data could be calculated using tools
such as Rhino.Inside®.Revit, or other means.
4
CONCLUSION
The new plugins for Rhino and Grasshopper of One Click
LCA have proven to have the potential to enhance the early
stages of the design phase by providing the design team with
a workflow for efficiently and accurately implementing LCA
in the design phase. They improve current parametric
strategies to reduce building embodied carbon in early design
stages [8, 9] by implementing a more extensive construction
materials EPD database in the Rhino + Grasshopper
environment, by providing an user-friendly interface and an
object-oriented structure, by adding automatic result
visualization options and by enabling an export process to
the web platform for additional verifications and comparison
with benchmark projects.
These tools aim at encouraging designers, who might not
even be advanced Rhino and Grasshopper users, to
implement LCA in their designs also for projects that are not
explicitly asked to obtain a green certification and thus fight
climate change from within the building industry.
Furthermore, their ease of use and pedagogic graphic results
(see Figure 3) make them appropriate for introducing them
into the education system to raise environmental awareness
among the next generation of architects and engineers.
Finally, it must be pointed out that the proposed design
strategy relies on chosen environmental profiles. Generic
LCA profiles are provided at country level precision, and
users can use manufacturer specific EPDs. However,
manufacturing markets also vary locally. All users may not
be able to evaluate the material market for their location, and
this introduces uncertainty to the results. Addressing this
would require a solution to identify the most representative
baseline product for each project location, also considering
the high variance in commercially feasible transport
distances between concrete, steel and CLT materials for
example.
Other topics for further research include implementing and
connecting the impact of retained design to the operational
carbon footprint [4], incorporating Design for Disassembly
and Design for Adaptability into the optimization strategy
and how to implement decision-tree algorithms for
architectural optimization in terms of embodied carbon [9],
and tracking the progression of project carbon footprint and
LCA over the different design phases of project and the as-
built results.
REFERENCES
1. Carbon Dioxide Information Analysis Center (CDIAC);
Global Carbon Project (GCP), https://cdiac.ess-
dive.lbl.gov/ trends/emis/meth_reg.html
ourworldindata.org/co2-andother-greenhouse-gas-
emissions
2. Sudipto Das, 'Illegal Sand Mining' West Bengal, India,
2010
3. Khasreen, M. M., Banfill, P. F. G., & Menzies, G. F.
(2009). Life-cycle assessment and the environmental
impact of buildings: A review. Sustainability, 1(3), 674–
701. https://doi.org/10.3390/su1030674
4. Asdrubali, F., Baldassarri, C., & Fthenakis, V. (2013).
Life cycle analysis in the construction sector: Guiding
the optimization of conventional Italian buildings.
Energy and Buildings, 64, 73–89.
https://doi.org/10.1016/j.enbuild.2013.04.018
5. Antón, L. Á., & Díaz, J. (2014). Integration of life cycle
assessment in a BIM environment. Procedia
Engineering, 85, 26–32.
https://doi.org/10.1016/j.proeng.2014.10.525
6. Cichocka, J. M., Browne, W. N., Ramirez, E. R., &
Rodriguez, E. B. T.-I. C. on C.-A. A. D. R. in A. (2017).
Optimization in the architectural practice. An
International Survey. Caadria, April, 387–397.
http://papers.cumincad.org/data/works/att/caadria2017_
155.pdf
7. Bach, R., Mohtashami, N., & Hildebrand, L. (2019).
Comparative overview on LCA software programs for
application in the façade design process. Journal of
Facade Design and Engineering, 7(1), 13–26.
https://doi.org/10.7480/jfde.2019.1.2657
8. Basic, S., Hollberg, A., Galimshina, A., & Habert, G.
(2019). A design integrated parametric tool for real-time
Life Cycle Assessment - Bombyx project. IOP
Conference Series: Earth and Environmental Science,
323(1). https://doi.org/10.1088/1755-
1315/323/1/012112
9. Hollberg, A. (2016). A parametric method for building
design optimization based on Life Cycle Assessment.
November.
10. World's fastest Building Life Cycle Assessment
software - One Click LCA. (2020). Retrieved 13
December 2020, from https://www.oneclicklca.com/
11. Pasanen, P., & Castro, R. (2019). Carbon Heroes
Benchmark Program - Whole building embodied carbon
profiling. IOP Conference Series: Earth and
Environmental Science, 323(1).
https://doi.org/10.1088/1755-1315/323/1/012028
12. Preisinger, C. (2013). Linking structure and parametric
geometry. Architectural Design, 83(2), 110–113.
https://doi.org/10.1002/ad.1564
13. Hestermann, U., Rongen, L., Hestermann, U., &
Rongen, L. (2018). Nachhaltig Konstruieren. In
Frick/Knöll Baukonstruktionslehre 2.
https://doi.org/10.1007/978-3-658-21913-0_1
14. Tedeschi, A. (2011). Parametric architecture with
Grasshopper®. Brienza, Italy: Le Penseur.
15. Felton, D., Fuller, R., & Crawford, R. H. (2014). The
potential for renewable materials to reduce the
embodied energy and associated greenhouse gas
emissions of medium-rise buildings. Architectural
Science Review, 57(1), 31–38.
https://doi.org/10.1080/00038628.2013.829022
16. Petit-Boix, A., Roigé, N., de la Fuente, A., Pujadas, P.,
Gabarrell, X., Rieradevall, J., & Josa, A. (2016).
Integrated Structural Analysis and Life Cycle
Assessment of Equivalent Trench-Pipe Systems for
Sewerage. Water Resources Management, 30(3), 1117–
1130. https://doi.org/10.1007/s11269-015-1214-5
17. Venkatarama Reddy, B. V., & Jagadish, K. S. (2003).
Embodied energy of common and alternative building
materials and technologies. Energy and Buildings,
35(2), 129–137. https://doi.org/10.1016/S0378-
7788(01)00141-4
18. Zeitz, A., Griffin, C. T., & Dusicka, P. (2019).
Comparing the embodied carbon and energy of a mass
timber structure system to typical steel and concrete
alternatives for parking garages. Energy and Buildings,
199, 126–133.
https://doi.org/10.1016/j.enbuild.2019.06.047
19. Breton, C., Blanchet, P., Amor, B., Beauregard, R., &
Chang, W. S. (2018). Assessing the climate change
impacts of biogenic carbon in buildings: A critical
review of two main dynamic approaches. Sustainability
(Switzerland), 10(6).
https://doi.org/10.3390/su10062020
20. Halpern, A. B., Billington, D. P., & Adriaenssens, S.
(2017). Nervi’s isostatically inspired ribbed floors: From
the ribbed floor slab systems of pier luigi nervi. Model
Perspectives: Structure, Architecture and Culture,
September 2016, 123–131.
https://doi.org/10.4324/97813150
21. Sahab, M. G., Toropov, V. V., & Gandomi, A. H.
(2013). A Review on Traditional and Modern Structural
Optimization: Problems and Techniques. In
Metaheuristic Applications in Structures and
Infrastructures (First Edition). Elsevier Inc.
https://doi.org/10.1016/B978-0-12-398364-0.00002-4
22. Otovic, A. P., Jensen, L. M. B., & Negendahl, K.
(2016). Expansion in Number of Parameters: Simulation
of Energy and Indoor Climate in Combination with
LCA. 2016 Ashrae Annual Conference Papers, June.
23. Rutten, D. (2013). Galapagos: On the logic and
limitations of generic solvers. Architectural Design,
83(2), 132–135. https://doi.org/10.1002/ad.1568
24. Vierlinger, R., & Hofmann, A. (2013). a Framework for
Flexible Search and Optimization in Parametric Design.
Proceedings of the Design Modeling Symposium
25. Apellániz, D. (2021). Implementation of a finite element
software API in a visual programming environment.
IASS Annual Symposium 2020/21 and Surrey 7th
Inspiring the Next Generation 23-27 August 2021,
Accepted abstract.
