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RhinoCircular: Development and Testing of a Circularity Indicator Tool for Application in Early Design Phases and Architectural Education

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RhinoCircular is a CAD plugin developed within the Circular Construction Lab (CCL) at Cornell University that assesses a building design’s environmental impact in respect to its embodied carbon values and circularity: the degree to which design solutions minimize extraction and waste in favor of reusable, recyclable and renewable material resources. Over their full life cycle, current buildings account for 39% of carbon dioxide emissions [1] and more than 50% of resource extraction and solid waste production. [2,3] As a way to overcome the social, economic, and environmental problems of this linear economic system, the concept of the circular economy is increasingly gaining attention. Activating the built environment as a material reserve for the construction of future cities would not only provide valuable local resources, but also potentially prevent up to 50% of the industry’s emissions by capitalizing on embodied carbon. [1] However, this requires radical paradigm shifts in how we design and construct buildings (e.g. materials selection/ design for disassembly), and in how resources are managed within the built environment. Buildings and regions need to anticipate stocks and flows of materials, documenting and communicating which materials in what quantities and qualities become available for reuse or recycling where and when. RhinoCircular allows direct and immediate feedback on design decisions in respect to formal deliberations, structural considerations, material selection and detailing based on material passports and circularity indicators. It can be integrated in existing and complex workflows and is compatible with industry standard databases while providing its own essential dataset complementing missing information.
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2020 AIA/ACSA Intersecons Research Conference: CARBON 1
Keywords: circular construcon, circular economy, circularity
indicator, recycling, reuse
RhinoCircular is a CAD plugin developed within the Circular
Construcon Lab (CCL) at Cornell University that assesses
a building design’s environmental impact in respect to its
embodied carbon values and circularity: the degree to which
design soluons minimize extracon and waste in favor of
reusable, recyclable and renewable material resources.
Over their full life cycle, current buildings account for 39%
of carbon dioxide emissions [1] and more than 50% of
resource extracon and solid waste producon. [2,3] As a
way to overcome the social, economic, and environmental
problems of this linear economic system, the concept of the
circular economy is increasingly gaining aenon. Acvang
the built environment as a material reserve for the construc-
on of future cies would not only provide valuable local
resources, but also potenally prevent up to 50% of the
industry’s emissions by capitalizing on embodied carbon.
[1] However, this requires radical paradigm shis in how
we design and construct buildings (e.g. materials selecon/
design for disassembly), and in how resources are managed
within the built environment. Buildings and regions need
to ancipate stocks and ows of materials, documenng
and communicang which materials in what quanes and
quali es be come availabl e for re use or recycl ing wh ere and
when. RhinoCircular allows direct and immediate feedback
on design decisions in respect to formal deliberaons, struc-
tural consideraons, material selecon and detailing based
on material passports and circularity indicators. It can be
integrated in exisng and complex workows and is compat-
ible with industry standard databases while providing its
own essenal dataset complemenng missing informaon.
INTRODUCTION
Globally, the construcon industry is the biggest consumer
of energy and materials. Over their full life cycle, buildings
account for 39% of carbon dioxide emissions [1] and more than
50% of resource extracon and solid waste producon. [2,3]
As a way to overcome the social, economic, and environmental
problems of the current linear economic system, the concept
of the circular economy (CE) is increasingly gaining aenon.
A CE has been dened as “...one that is restorave and regen-
erave by design and aims to keep products, components,
and materials at their highest ulity and value at all mes.”
[4] The consequent closing of producon and consumpon
loops oers not only the possibility to end the loss of valuable
nite resources, but also to reduce dependencies on global,
volale resource markets, prevent greenhouse gas emissions,
migate the eects of the climate crisis, and support new busi-
ness models and green job opportunies. [5-6]
Since rates of construcon are signicantly higher than
demolion and discard, society is building up an important
economy-wide anthropogenic material stock. [7] Today, the
amount of many metals and minerals bound within the built
environment has already outgrown their respecve naturally
occurring reserves. [8] By some esmates, exisng buildings
account for as much as 90% of all materials ever extracted, [9]
hastening calls for the development of technologies and strat-
egies for circular resource ulizaon. Addionally, as global
and local actors seek to address climate concerns the implicit
value associated with embodied carbon, labor, knowledge and
water can impact material valuaon going forward. The loss
of this signicant exisng stock of materials and the related
embodied values due to the current pracce of demolion
and landlling will consequently no longer be viable praccally,
environmentally, or economically.
Acvang the built environment as a material reserve for
the construcon of future cies would not only provide valu-
able local resources, but also potenally prevent up to 50%
of the industry’s emissions by capitalizing on embodied car-
bon. [1] However, this requires radical paradigm shis in how
we design and construct buildings (e.g. materials selecon/
design for disassembly), and in how resources are managed
within the built environment. Buildings and regions need to
ancipate stocks and ows of materials, documenng and
communicang which materials in what quanes and quali-
es become available for reuse or recycling where and when.
The current waste of resources is facilitated by the absence of
such relevant data on materials: Historically, the construcon
industry has not documented the stocks, ows, specicaons,
and values of building materials and components over me,
nor has it prepared this data for future use. In business, what
gets measured gets managed, so the availability and ulizaon
of this data represent one of the keys to developing material
loops crical to the CE.
RhinoCircular: Development and Tesng of a Circularity Indicator Tool
for Applicaon in Early Design Phases and Architectural Educaon
FELIX HEISEL
Circular Construcon Lab, Cornell University
CAMERON NELSON
Circular Construcon Lab, Cornell University
2RhinoCircular: Development and Tesng of a Circularity Indicator Tool for Applicaon in Early Design Phases and Architectural Educaon
Eorts by a number of organizaons over the last ten years
in creang and making available such data have oered
several dierent approaches, each with their advantages
and shortcomings. While top-down approaches focus on
macro-economic stascs as informaon source, boom-
up approaches extrapolate urban material stock and ow
informaon based on a combinaon of indicators such as the
material composion of typical buildings and oor surface
area. As an example, the TABULA project by Intelligent Energy
Europe surveyed exisng buildings and compared them to
one of several building types, organized regionally, in order
to enable esmaon of the material stock in the already-built
environment. [10] Expanding on this methodology, a study of
the city of Chiclayo, Peru, used Google Street View and munici
-
pal cadasters (legal registers of property boundaries and
value) as an ecient means to survey the city’s residenal sec-
tor. [11] Most recently, several studies combined boom-up
approaches with geographical informaon systems (GIS) and
airborne light detecon and ranging (LiDAR) data as addional
indicators to esmate the building stock of Esch-sur-Alzee
(FR), Luxembourg City (LU), Atlanta (US), Melbourne (AU),
Beijing (CH), Odense (DK), and Ithaca (US). [12-17]
The emerging concept of materials passports (MP) oers a
technical soluon to the missing building data documenta-
on, by providing digital twins of buildings, containing detailed
inventories of materials and products used, as well as their
specicaons, locaon and connecon details. Eorts by
Madaster, BAMB or EPEA in Europe oer plaorms for storing
such comprehensive informaon about materials, oen inte-
grang building informaon modeling (BIM) as the source for
volume calculaons. As a case-in-point, the Urban Mining and
Recycling (UMAR) [18] Unit by Werner Sobek, Dirk E. Hebel and
Felix Heisel within the Empa NEST in Dübendorf, Switzerland,
wa s desi gned and con s tructe d as a ful ly cir cula r prototypol o g y,
[19] achieving a 96% circularity rang [20] on the Madaster
plaorm - the highest of any known building registered on the
plaorm so far.
However, the broad applicaon of MPs to date is restricted
by several conceptual and technical limitaons: Firstly, MP
generaon unl now has been largely concentrated on the
documentaon of newly constructed buildings, consequently
missing out on two important phases of the building use cycle:
1) The already exisng building stock including the aforemen-
oned - so far undocumented - material stock / urban mine, as
well as 2) the early-design phase where MP thinking and inte-
graon could play a signicant role in both closing the current
supply/ demand mismatch of reusable materials and trans-
forming new construcons into the material depots (rather
than urban mines) of the future. A consequent standardizaon
and central registraon of MPs covering all buildings and com
-
ponents of the built environment in material cadasters will be
a prerequisite for the circular management of resources.
Secondly, while the calculaon methods for circularity indi-
cators have been established in the past years (see method
secons below), the underlying and necessary data points are
sll mostly unavailable to date. Many material ow calculaons
are missing informaon especially towards the end-of-use
phase of buildings and thus complicate scienc analysis of
design decisions. In the case of UMAR, MP creaon required
building substanal databases of custom materials. Such work
is at best tedious, and at worst prohibively me-consuming
for smaller rms, individual designers, and students, assum-
ing the ne ces sar y data points can even be found . Addi onall y,
while such an approach might be suitable to record what
congured materials happen to be reusable in an already-
planned building, it cannot provide the necessary feedback to
the design decisions themselves and thus does not represent
a fundamental shi away from the linear, exploitave thinking
that is one root cause of the global resource predicament.
This paper describes the development of a new tool address-
ing these challenges. RhinoCircular is a Rhi no3D/ Gras sho pper
plugin developed within the Circular Construcon Lab (CCL) at
Cornell University, that allows a direct and immediate feedback
on design decisions in respect to formal deliberaons, struc-
tural consideraons, material selecon and detailing based on
MPs and circularity indicators (CI). It can be integrated in exist-
ing and complex workows and is compable with industry
standard databases while providing its own essenal dataset
complemenng missing informaon. The following para-
graphs will highlight the funconality of the tool and provide
an outlook for its applicaon in architectural design studios,
research projects as well as architectural pracse.
RHINOCIRCULAR
RhinoCircular is a CAD plugin that assesses a building design’s
environmental impact in respect to its embodied carbon
values and circularity: the degree to which design soluons
minimize extracon and waste in favor of reusable, recy-
clable and renewable material resources. Embedded into the
Grasshopper environment of the popular design soware
Rhinoceros3D, the tool consists of several components that
can be combined or connected through ‘visual’ scripng to suit
the specic needs of a proposed project in any design phase
or on any level of detail. The open structure further allows
the seamless integraon of RhinoCircular components into
exisng workows, be they sequenal, generave, paramet-
ric or automated.
Aiming to support a holisc approach to operaonal and
embodied carbon analyses and trade-o strategies on the
building and urban scale, RhinoCircular interacts with climate
and energy simulaon workows such as ClimateStudio [21]
or AutoZoner, [22] as well as geometr y automaon tools such
as AutoFramer. [23] The soware is further compable with
the industry standard databases such as Madaster by oer-
ing components to read materials and write MPs into specic
2020 AIA/ACSA Intersecons Research Conference: CARBON 3
porolios using available applicaon programmin interfaces
(API). In order to allow the intended seamless exchange of data
within such a generave design and simulaon environment,
the authors are currently also part of a team developing a com-
prehensive data set, namely BuildingRepo, [24] a forthcoming
open-source building repositor y available online and through
its own Grasshopper plug-in.
CIRCULARITY INDICATORS
The CI itself is a number between 0 and 1 calculated via a set
of equaons from parameters such as lifespan, eciency of
recycling, and fracon of feedstock taken from renewable,
recycled, or reused sources. The equaons were rst devel-
oped by the Ellen MacArthur Foundaon in 2016, [25] and
further adapted for their specic applicaon in the built envi-
ronment by Madaster in 2018. [26] For their applicaon within
RhinoCircular, certain variables are computed directly from
Nurbs and mesh geometry. As summarized in Table 1, values of
interest can be organized into three categories: basic param-
eters provided directly by the user or the respecve material
databa se, compu ted pa r ame ters which ca n be wri en in terms
of the basic parameters, or metrics computed from a combi-
naon of basic and computed parameters. Values are further
organized by the period of the building’s use-cycle analysis to
which they pertain: construcon, use, or end-of-use phases.
Finally, the overall CI of a product is calculated from the linear
ow index (LFI) and ulity fac tor (F(X)), as dened below:
F(X) = 0.9/CIuse
LFI = (V+W) / (2M + (WF - WC)/2)
CItotal = 1-LFI * F(X)
Key to construcng complex models is the ability to break a
building down into a hierarchy of architectural components,
ea ch of which might it self be divid e d int o sma ller compo n ent s .
These components are referred to as products. Compung
metrics for compound products follows the general rule of
mass-weighted sum:
∑ (CIsub -product * Msub-produc t) / Mproduct
METHODS AND COMPONENTS
RhinoCircular consists of several components, divided into
categories of material, product, and analysis. Figure 1 depicts
the user interface of Rhinoceros3D (le) and RhinoCircular
in Grasshopper (right). Results are displayed directly in the
modelling environment for easy reference within the design
workow, while visual scripng of components is done
within Grasshopper.
Materials. A standard workow begins with the selecon
of materials; this can be accomplished through the “Load
Material” component, which displays a list encompassing
those materials from the selected database and which is
searchable by class of material (wood, stone, plasc, texle,
organic, ceramic, and metal). This can be fed into any of the
product components. A toggleable parameter of the “Load
Material” component triggers an automac download of the
latest dataset from one of a selecon of sources including
Madaster, ensuring this data remains up-to-date and ed into
an enterprise-level repository. Alternavely, one can use the
“Custom Material” component to either tweak certain data
points of a catalogue material, as for instance if one were to
use the density and lifeme esmates of a stock material but
provide gures for eciency of recycling that were more rep-
resentave of their locality; or to create a new material from
scratch using outside data, as for instance if one were to use
a building product from a specic supplier’s catalogue that
provided such informaon. Given enough informaon, the
“Custom Material” component will calculate remaining values
automacally, sparing the need to explicitly enumerate all of
the relevant elds.
Product. The second stage of a typical workow would begin
by assigning these materials to components of the 3D build-
ing geometry, called products. This 3D model can be explicitly
referenced from geometry in the standard Rhinoceros3D edit-
ing window, or can be parametrically generated from within
Grasshopper, leveraging the exibility and power of this node-
based scripng tool. Products can represent anything from a
door knob to an I-beam to an enre façade system, but begin
as an object of a single material. These inial products contain
informaon about the referenced geometry, its volume and
density (and hence mass), and the material assigned to it. In
addion to the product object itself, these components also
output the CI values for the product in the construcon, use,
and end-of-use phases, and overall.
Table 1. Parameters and metrics for CI calculaon dependent on
use-c ycle phase, based on [28,29]
4RhinoCircular: Development and Tesng of a Circularity Indicator Tool for Applicaon in Early Design Phases and Architectural Educaon
This base product can be enumerated in one of four ways,
each represented by its own constructor component: length,
area, volume, or quanty. Length-based or linear products
can reference curve geometry and must provide the cross-
seconal area in order to calculate volume, making it easy,
for instance, to iterate through dierent gauges of rope or
wire within a parametric design workow while working with
easy-to-manipulate curve geometry. Area-based products
can reference surfaces or meshes and must provide a thick-
ness. Volume-based products can reference solid geometry,
either BReps (Nurbs boundary representaons) or meshes,
from which volume is calculated directly. Lastly, for products
that do not t in these categories, or which have no explicit
3D geometry associated with them, the quanty component
allows manual entry of the volume and enables one to group
large numbers of similar products as would be useful for items
like nails, studs, and screws.
Importantly, these components display three clickable buons
labeled “Inaccessible,” “Fixed in place,” and “Nonstandardized.”
Toggling the buons changes them to read “Accessible,”
“Disassemblable,” and “Standardized.” If any of the buons
are le untoggled, the product is considered irremovable and
therefore the end-of-use CI value will default to 0. Therefore,
it is expected that these must be toggled each me; this is
a deliberate pedagogical choice to highlight the queson of
reversible joinery so that the user is consciously aware of its
eect on the overall circularity of a building.
The four base product types are the atomic units of a build-
ing circularity model, which can be viewed as a tree in which
each er represents a relevant level of organizaon within the
building, as displayed in Figure 2. In each successive er prod-
ucts from the previous er are merged using the “Composite”
component, which takes any number of products as input
and produces a single, combined product whose CI values are
taken as the weighted sum by mass of those of the inputs.
Not necessarily a unidireconally-branching tree, the hierar-
chy can contain mulple organizaons at the same er (for
instance, grouping products by supplier, or by building layer);
however, to avoid overcounng, an error is generated if the
same geometry is merged with itself downstream. The nal
merging into a single product represents the building as a
whole, giving the total values for all CIs.
Figure 1. RhinoCircular user interface in Rhinoceros3D and Grasshopper. Circular Construcon Lab, Cornell University.
Figure 2. Organizaon tree of building circularity model within
RhinoCircular. Circular Construcon Lab, Cornell Universit y
2020 AIA/ACSA Intersecons Research Conference: CARBON 5
Analysis. A subset of components are specically concerned
with the visualizaon and publishing of the computed metrics.
The “Passport” component takes as input a product, typically
the composite product represenng the enre building, and
generates a formaed, printable le displaying a summary
of all key metrics. The “Selectcomponent renes a list of
products according to an input criterion: a material to match
against, a 1D domain of CI values to test for inclusion, or the
sasfacon of the three accessibility criteria described above.
Each product contains geometry data such that by selecng its
component in Grasshopper, the corresponding geometry may
be highlighted in the Rhinoceros3D viewport for quick analysis.
In combinaon with the “Select” component, the passing of
geometry data upstream also allows for custom workows
such as highlighng geometry with a color gradient according
to CI or material type. The “Graph” component displays a bar
graph within a widget in the grasshopper canvas. From the
menu the user can select which of the calculated metrics to
display for the input product. One can addionally select how
to organize the x-axis; for example, one could display the use
phase CI for each layer in the CAD le, or the mass weighted CI
for each material in the construcon. The component outputs
include the names and values of each column of the bar graph.
An example is shown in Figure 3.
LIMITATIONS AND SCOPE
In contrast to exisng soware applicaons that document
design decisions based on detailed BIM models for the cre-
aon of MPs, RhinoCircular is developed as an early design
tool to support and inuence design decisions in the process.
This fact naturally results in a lower level of model accuracy
and detail which needs to be taken into account when cal-
culang CI and embodied carbon values. Consequently, the
soware is running certain automisaon processes to ll in
the blanks when required data points for the calculaon are
not yet available in the model or reverts to default values from
literature. While we do not see this as problemac - the goal of
the soware is indeed to allow quick informed decisions in the
mes of greater uncertainty, the level of data accuracy in the
early-design phase needs to be acknowledged. With increasing
model accuracy throughout the stages of the design process,
RhinoCircular increasingly renes its calculaons.
All CI tools are currently sll limited by the availability of data
on material ows especially towards the end-of-use phase
of the cycle. RhinoCircular aims to migate this limitaon
through compability with several sources and interfaces, as
well as through the ongoing development of its own dataset in
the background. Addionally, material cycle-specic data such
as eciency of recycling or embodied carbon values are highly
dependant on the locaon of the building, as energy mixes in
producon, transport lengths and local producon, construc-
on and recycling condions determine the calculaon of such
inputs. Consequently, RhinoCircular asks for a user-dened
parameter on the locaon of the building, however, most data
bases are not able to interpret or adjust values depending on
specic locaons.
Figure 3. RhinoCircular displays calculaon results directly within the modelling environment. Circular Construcon Lab, Cornell University.
6RhinoCircular: Development and Tesng of a Circularity Indicator Tool for Applicaon in Early Design Phases and Architectural Educaon
With live recalculaon of CI during the design process, it
becomes possible for the designer to adjust geometry accord-
ingly. However, the potenal for interoperability with other
early design analysis tools oers even greater potenal. For
example, one could adjust the span of a load bearing beam
and have the cross-secon automacally recalculated with a
nite element modeling tool such as the Grasshopper plugin
“Karamba,” [27] then instantly see the impact this has on cir-
cularity as the CI is recalculated for the beam’s new mass. This
seamless workow however will only be enabled by central-
ized material databases such as the forthcoming BuildingRepo
where material properes related to all manner of design
objecves, from circularity to environmental and mechanical
performance, can be accessed side-by-side. This contrasts
with common pracce, wherein separate, specialized data-
bases are leveraged for each simulaon tool, which can make
it dicult to ensure that data refers to the same material from
on e tool to ano ther. To this end, Rhin o Circular has be e n dev el-
oped to be as agnosc as possible to the data source, so that it
can easily be graed into more holisc workows such as the
BuildingRepo toolkit in the future.
DISCUSSION AND OUTLOOK
The implementaon of a CE in the built environment through
circular construcon is technically feasible already today, as
the examples of UMAR and other lighthouse construcons
around the globe demonstrate. However, its industrial and
large-scale applicaon requires fundamental paradigm shis
in design and construcon methodologies, economic and
social models as well as material producon and sourcing. A
detailed documentaon of the built environment over me
represents a precondion for the closing of material cycles in
this scenario. Most importantly however, it is a design task to
develop circular soluons that implement and reapply exist-
ing resources in ways that do not create waste in the process
and allow for the connuous use of materials, products and
components at their highest ulity and value.
This design process requires new tools to support and allow
informed decision making and matching of supply and demand
within an urban circular system. In this context, RhinoCircular
provides an integrated tool for predicng the impact of espe-
cially early-design decisions on the circularity performance
of buildings. It allows architects, engineers, and planners to
maximize the reusability of buildings from the outset, giving
meaningful feedback about circularity even with incomplete
informaon. A 2012 survey reported that 91% of large com-
pa nie s are us ing BI M, wh ile on ly 49% of sma ller rms re ported
the same. [28] We may expect similar trends in the adopon
of tools for circular building, unless they can be easily and
seamlessly integrated in exisng and low-cost workows.
RhinoCircular aims to be one such soluon.
ENDNOTES
1. Architecture 2030. 2019. “New Buildings: Embodied Carbon.”
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Chapter
The potential of urban mining is getting greater. From the global view, the potential of urban mining, namely the estimated amount of on-surface stock which has been mine form the geo-sphere into the techno-sphere, is comparative to natural resource which is still in geo-sphere as underground stock. However, practical recycling of metals are still in the stage of developing, and depending on the country. As an example, ultimate potential of urban mine in Japan was estimated. The differences between input of each metal contents and output of it were considered to be accumulated. I/O method was combined to estimate the metal contents in exported products. Japan, which is considered a typical exporter of materials, has great potential of urban mining which comes from domestic demand of products. However, real activity of development of urban mine, namely recycling, is not so effective, especially for minor metals which sometime called rare metals from the viewpoint of the importance in industries. We need to develop the technology and system for urban mining, just now.