Reusing Timber Formwork in Building Construction: Testing, Redesign, and Socio-Economic Reflection

Abstract

In 2018, the construction sector was responsible for 39% of the worldwide energy and process-related carbon dioxide emissions (Global Alliance for Buildings and Construction et al., 2019). This is partly due to the embodied carbon, which represents the carbon emissions related to building construction and material production (LETI, 2020). While zero energy buildings and zero energy renovations start to get the operational carbon down, the circular economy aims to do this by closing material loops and stimulating the reuse of discarded materials in building construction (Ellen McArthur Foundation et al., 2015). Although it is not a new phenomenon, material reuse does require a substantially different approach and is at this point not yet common in the building industry. This is especially true for load-bearing components. This article presents a pilot project for the reuse of discarded timber formwork for the construction of the façade and (load-bearing) substructure of a new house. Through this pilot case and by reflecting on a series of similar cases, it studies the remaining challenges for material reuse but also proposes and assesses redesign strategies that will allow upscaling the reuse of timber formwork. The project shows that although waste, material, and money can be saved by using reclaimed materials , it does complicate the design and construction process and, as such, does not necessarily reduce the total project budget. Moreover, for reuse to become a current practice, new design approaches and collaborations will need to be established. Finally, socioeconomic factors must be considered to increase the acceptance of reclaimed materials in new building construction.

Full text

Urban Planning (ISSN: 2183–7635)
2022, Volume 7, Issue 2, Pages 81–96
https://doi.org/10.17645/up.v7i2.5117
Article
Reusing Timber Formwork in Building Construction: Testing, Redesign,
and Socio‐Economic Reflection
Arno Pronk 1, Stijn Brancart 2,*, and Fred Sanders 3
1Faculty of the Built Environment, Eindhoven University of Technology, The Netherlands
2Faculty of Architecture and the Built Environment, Delft University of Technology, The Netherlands
3CPONH NGO, The Netherlands
* Corresponding author (s.brancart@tudelft.nl)
Submitted: 18 November 2021 | Accepted: 10 March 2022 | Published: 28 April 2022
Abstract
In 2018, the construction sector was responsible for 39% of the worldwide energy and process‐related carbon dioxide
emissions (Global Alliance for Buildings and Construction et al., 2019). This is partly due to the embodied carbon, which
represents the carbon emissions related to building construction and material production (LETI, 2020). While zero energy
buildings and zero energy renovations start to get the operational carbon down, the circular economy aims to do this by
closing material loops and stimulating the reuse of discarded materials in building construction (Ellen McArthur Foundation
et al., 2015). Although it is not a new phenomenon, material reuse does require a substantially different approach and is
at this point not yet common in the building industry. This is especially true for load‐bearing components. This article
presents a pilot project for the reuse of discarded timber formwork for the construction of the façade and (load‐bearing)
substructure of a new house. Through this pilot case and by reflecting on a series of similar cases, it studies the remain‐
ing challenges for material reuse but also proposes and assesses redesign strategies that will allow upscaling the reuse
of timber formwork. The project shows that although waste, material, and money can be saved by using reclaimed mate‐
rials, it does complicate the design and construction process and, as such, does not necessarily reduce the total project
budget. Moreover, for reuse to become a current practice, new design approaches and collaborations will need to be
established. Finally, socio‐economic factors must be considered to increase the acceptance of reclaimed materials in new
building construction.
Keywords
circular economy; circular housing; CO2reduction; material reuse; resource efficiency; sustainable architecture
Issue
This article is part of the issue “Zero Energy Renovation: How to Get Users Involved?” edited by Tineke van der Schoor
(Hanze University of Applied Sciences) and Fred Sanders (CPONH NGO).
© 2022 by the author(s); licensee Cogitatio (Lisbon, Portugal). This article is licensed under a Creative Commons Attribu‐
tion 4.0 International License (CC BY).
1. Introduction
Considering the current climate and sustainability crisis,
a lot of focus is put on reducing building‐related carbon
emissions. This is not surprising, since the building sec‐
tor is responsible for almost 40% of worldwide energy
and process‐related CO2emissions (Global Alliance for
Buildings and Construction et al., 2019). While policy
makers and the construction sector are moving increas‐
ingly towards the construction of zero energy build‐
ings, another aspect of sustainable construction is slowly
reaching the foreground: the embodied carbon. This is
the carbon that is emitted during the construction, main‐
tenance, and end‐of‐life processing of a building and its
materials (LETI, 2020). The embodied carbon of build‐
ings has been underrepresented in the sustainability
discourse in favour of the more acute need to lower
operational carbon. Some studies even suggest that the
embodied carbon of buildings is increasing due to higher
material consumption in low and zero energy buildings
Urban Planning, 2022, Volume 7, Issue 2, Pages 81–96 81

(Giordano et al., 2017). Others show that embodied
carbon is much more related to the types of buildings
and the materials that were used (Hoxha et al., 2017).
Overall, however, with decreasing operational carbon,
the embodied carbon is starting to represent the larger
share of the total carbon emissions of buildings (LETI,
2020). Without efficient strategies for reducing it, the
construction sector will never be able to effectively and
adequately reduce its environmental impact. Reducing
the impact of material use in construction cannot be con‐
sidered separately from the recent developments regard‐
ing the circular economy (Ellen McArthur Foundation
et al., 2015). Much of this material impact is related
to the extraction of virgin resources and the waste
management of discarded materials after all. Circular
construction aims at closing material loops by reusing
or recycling construction materials or by growing the
required resources in a biological cycle (Galle et al., 2019).
Effective reuse of building materials requires strategies
for the repurposing of discarded materials on one hand
while transitioning towards a more futureproof construc‐
tion practice that extends the functional life of new build‐
ings and materials on the other. The latter, which is gen‐
erally called design for change, aims at facilitating reuse
and repurposing of buildings and building elements in
the future (Brancart et al., 2017). The former allows an
immediate reduction of both waste production and vir‐
gin material use, and can, as such, lower embodied car‐
bon instantly (Brütting et al., 2020). This article focuses
on direct reuse.
While not yet common practice, material reuse is not
a new phenomenon. Many interesting examples have
been scattered throughout history, especially at times
when material costs where high and labour was much
less expensive (Addis, 2012; Fivet & Brütting, 2020).
Within the context of the circular economy, the recla‐
mation of building materials during demolition, so‐called
urban mining, is gradually finding its way into practice
(Arora et al., 2020; Koutamanis et al., 2018). Reclaimed
bricks, interior doors, and roof and floor tiles start mak‐
ing up a second‐hand market, as they are often being
sold by demolition companies (Devlieger et al., 2019).
Exemplary cases do however show that the use of
reclaimed materials requires specific attention and cur‐
rent design approaches often fail to accommodate them
(Kawa, 2021). In many cases, the exchange of materials
between a demolition site and a construction project
will require careful planning. The main challenges for
reuse appear to be situated on a social and organisa‐
tional level (Gorgolewski, 2008). Moreover, unknowns
about the material properties often require additional
studies or testing (Brütting et al., 2019). As a result,
reclaimed materials are often applied in building layers
with low‐performance criteria where quality assurance
is not required or can be more easily done.
This article zooms in on the use of reclaimed timber.
It argues that the reuse of building materials and in this
case, timber can help substantially lower the embodied
carbon levels of buildings. Yet, to increase the uptake
of reclaimed building components, some barriers need
to be overcome. Therefore, the article first aims to pro‐
vide a general overview of reuse strategies and current
limitations, based on a review of built cases. Secondly,
it goes in‐depth on one specific challenge: the reuse
of discarded timber formwork. The functional lifetime
of timber formwork is short compared to its technical
life. This currently leads to high amounts of waste and
loss of economic value. This article, therefore, studies
the reuse potential of formwork in housing construction
and investigates redesign strategies to increase it, based
on an A‐to‐Z case study for a new circular house on
IJburg Amsterdam, compared to several similar projects.
The research focuses on the following two specific ques‐
tions: What is the load‐bearing capacity of the formwork
elements? Which connection types will allow more effec‐
tive reuse?
Specific about the central case study is that one of
the building owners is also the project architect and prin‐
cipal investigator of this study. As such, he was actively
and positively involved in the material reuse. The other
residents, his family, and another family with which they
share the house, were less involved. While they acknowl‐
edged the value of a circular design and construction
approach, they were also concerned about the impact
on the building layout and appearance. This kind of
resistance is not uncommon. Aside from technological
challenges, there are also socio‐economic barriers to
overcome (Charef et al., 2021). Consumers are used to
choosing from extensive catalogues of buildings mate‐
rials. Moreover, they lack experience with and knowl‐
edge about circular products, their advantages and draw‐
backs. This results in a lack of confidence about the
durability, quality, and usability of the products, along
with a general resistance to change. Many of the stud‐
ied cases report such resistance in one or more of the
project stakeholders. Yet, open communication but espe‐
cially the quality of the design and finished project man‐
aged to persuade them. In most projects though, the
focus remains on the technological solutions, as this type
of sustainable construction is still in a more explorative
and experimental stage (Schut et al., 2016). While this
article does primarily consider the technological barriers
to material reuse, it does reflect on the socio‐economic
aspects that will be required to scale‐up circular construc‐
tion practices.
2. Building With Waste: Reclaimed Timber for Façades
and Load‐Bearing Construction
To better understand and position the pilot project that
is presented in the following sections, this article first
drafts a more general framework by reflecting on a series
of representative cases. These cases focus on the appli‐
cation of reclaimed timber products in façades and load‐
bearing structures. Figure 1 shows the nine selected
cases. Although they all share similarities as well as
Urban Planning, 2022, Volume 7, Issue 2, Pages 81–96 82

Figure 1. The nine selected project cases.
feature some unique characteristics, they can be roughly
divided into three groups. Cases 1 to 3 represent the
reuse of reclaimed building products like doors and win‐
dow frames in new façades. The EUROPA building is the
only of these cases in which the reclaimed elements—in
this case, window frames—were reapplied for the same
function. Cases 4 to 6 all include façades that were clad
with reclaimed materials from outside the building indus‐
try: from damaged cable reels over hardwood sheet pil‐
ing to used transport pallets. Cases 7 to 9 finally repre‐
sent the category of buildings in which reclaimed tim‐
ber is used as part of the load‐bearing structure. Such
cases are of particular interest in the scope of the pre‐
sented pilot project. They are however far less common
and underreported in (scientific) literature.
Table 1 summarises the most relevant project infor‐
mation and lessons learned. These were gathered from
existing literature (including scientific articles, new arti‐
cles, and interviews with designers or building own‐
ers). While each project is characterised by a distinct
approach, it is possible to draw some general conclusions.
Based on the variety of cases, it is reasonable to assume
that these conclusions can be generalised, though it is
also clear that many of the studied aspects should be
considered case by case. The analysis focuses on four
aspects: motivation, process, application, and cost.
In most cases, sustainability aspects like waste sav‐
ings and a reduction of the embodied energy provided
the main motivation for the application of reclaimed tim‐
ber. The choice for material reuse was generally part of
much broader sustainability ambitions related to energy
performance, circularity and, in the case of the Omega
Centre, even regenerative design. Yet, in all cases, the
designers or building owners point towards the improve‐
ment of the project’s overall architectural quality as one
of the main advantages of material reuse. The reclaimed
materials were made highly visible and often have a
prominent position in the project, even in cases like KEVN
and the Materials Testing Facility, where they are part
of the load‐bearing structure. In some projects, the ori‐
gin of the materials plays a role in the design concept.
This is especially clear in the case of Kaap Skil, where
Urban Planning, 2022, Volume 7, Issue 2, Pages 81–96 83

maritime sheet piling was used in the façade of a mar‐
itime museum, but also in the EUROPA building, with its
façade consisting of reclaimed window frames from all
EU member states.
The prominent position of the reclaimed timber in
the architectural concept warrants an equally prominent
position in the design and construction process. The lim‐
ited availability and often small volumes of reclaimed
materials, logistic considerations regarding transporta‐
tion and stocking, and the many unknowns related to
material properties and quality assurance require spe‐
cific actions. These differ fundamentally from the con‐
ventional approach, in which new building products are
often selected at a later stage or the end of the pro‐
cess. In many of the presented cases, the design team,
therefore, collaborated with reuse experts. Two lessons
Table 1. An overview of the basic project info and most important lessons learned.
Case Reuse Lessons Learned References
Circular Pavilion Interior doors as The final design had to be adapted to Valenzuela (2015)
Paris (FR), 2015 façade cladding the exact sizes of the door panels and Kawa (2021)
Encore Heureux Architects
Crèche Justice Interior door Material changed for final design Myers (2020) and
Paris (FR), 2020 (frames) as façade based on unsuitable performance Kawa (2021)
BFV architects with cladding
Bellastock
EUROPA building Window frames A double façade guarantees adequate
Brussels (BE), 2017 from different EU energy performance, a mathematical
Samyn & Partners countries system defines the seemingly random
pattern of the differently sized frames Wright (2017)
Villa Welpeloo Timber from cable The design of the façade is based on Superuse Studios (2009)
Enschede (NL), 2009 reels as façade the size limitations of the reclaimed and Kawa (2021)
Superuse Studios cladding timber pieces
Kaap Skil Hardwood sheet Use of maritime wood enforced Opalis (n.d.) and
Texel (NL), 2011 piling as façade architectural concept for maritime Mecanoo (n.d.)
Mecanoo architecten with cladding museum, contractor attracted based
Pieters Bouwtechniek on involvement in demolition project
Kringloopwinkel Houten Transport pallet Reuse of pallet wood resulted in DGBC (2020)
Houten (NL), 2012 wood as façade considerable savings, the design and
Arcadis cladding outlook of the façade are defined by a
large variety of timber pieces
Materials Testing Facility Timber trusses, Underestimation of glulam’s strength, Public Architecture
Vancouver (CA), 1999 glulam beams as reclaimed timber a lot cheaper, strong (2011) and Brütting
Busby + Associates Architects floor decking involvement of partners, scepticism of et al. (2019)
with Fast & Epp Partners users turned to appreciation of result
KEVN Timber frames The frames were cut to make purlins Superuse Studios
Eindhoven (NL), 2020 from the same timber, the entire (2020)
Superuse Studios pavilion can be disassembled for
another reuse
Omega Center 90% of total timber Specifications should be flexible to Public Architecture
New York (USA), 2009 use, including allow changing material choices based (2011)
BNIM Architects with frames, panels, on availability, the involvement of a
Planet Reuse doors, beams reuse broker helps maintain a tighter
schedule, reclaimed timber is
considerably cheaper than new
FSC timber
Urban Planning, 2022, Volume 7, Issue 2, Pages 81–96 84

were drawn from almost every project: It is important
to prepare for material reuse early in the design pro‐
cess and the design and construction team need to be
sufficiently flexible to deal with and adapt to the many
unknowns. Additionally, it appears that strong collabora‐
tions, as well as open communication, were key in mak‐
ing the reuse work.
The selected cases all feature reclaimed timber in
façade and load‐bearing applications. In most cases, the
materials were applied for functions different from their
initial use. Even more so, several of the reclaimed materi‐
als originally weren’t building products at all. In almost all
cases the materials first had to be processed to be sized,
protected, and installed properly for their new function.
Thanks to its great workability, this is relatively simple
when using timber. While reclaimed materials are get‐
ting more and more common for the cladding of façades,
it is more difficult to find cases of reclaimed load‐bearing
structures. This is most likely due to the required per‐
formance levels and associated risks. These structural
requirements often ask for creative solutions. The tim‐
ber trusses in the Materials Testing Facility for example
were recomposed from the most qualitative pieces of
the reclaimed truss elements. Due to unknowns about
the structural integrity of the glulam beams, the design
and engineering team decided to apply them as floor
decking, thus overdimensioning the structure but also
avoiding having to rely on the strength of the glue (Public
Architecture, 2011).
A final important aspect is the cost. It is difficult
to provide a general conclusion or even make a mean‐
ingful comparison between the cases for this. After all,
the available budgets for the different projects differed
largely as well as the origin of the reclaimed materi‐
als and the technical complexity related to their reuse.
While the thrift shop in Houten was realised with a small
budget (one million euros for 1392 m2), shipping win‐
dow frames from all over Europe has undoubtedly only
increased the total project cost of the EUROPA build‐
ing. In general, savings can be made with respect to
the actual material cost. In most cases, these materials
would have been discarded as waste after all. Yet, the
logistics and additional work hours often increase con‐
siderably. In many cases, an additional partner had to be
added to the team or contractors and engineers needed
to be involved earlier and more intensively. Moreover,
temporary storage, transportation, and, in some cases,
prototyping and testing, ramp up the budget. As such, it
is not possible to say that material reuse will automati‐
cally result in a reduction of the project cost.
In most of these cases, the end user was not heav‐
ily involved in the building design and material selec‐
tion. Out of the nine projects, only Villa Welpeloo
(case 4) was realised on behalf of the actual end user.
The residents and building owners, a young couple, had
the express wish to build a sustainable home by inte‐
grating as many aspects of circular design as possi‐
ble. They commissioned a young architectural firm and
together they achieved 60% reuse of existing materials.
This required making some concessions, but these were
acceptable seen as the circular design was one of the ini‐
tial requirements. The other cases mainly concern pub‐
lic buildings and, as such, the end user was not inten‐
sively involved in the construction process and circular
design choices. Moreover, cases like the EUROPA build‐
ing, using a mix of different reclaimed window frames, or
Kaap Skil, using maritime wood in a maritime museum,
show that reclaimed materials are still mostly used in
“eye‐catching” applications. As such, they underline the
potential added value of circular design. This does how‐
ever avoid owners or end users having to make conces‐
sions in terms of expected interior appearance or sup‐
posed quality of materials that often hinder the applica‐
tion of reclaimed materials.
The reference projects show that qualitive mate‐
rial reuse can be achieved, but the exceptionality of
the buildings also shows that it remains a niche and
the use of reclaimed building materials has not yet
become commonplace in more everyday construction.
While the availability of used materials appears to be
increasing, their reuse is not yet established, partly
because the recycling of materials such as aluminium,
glass, and concrete granulates has already been per‐
fected (Rijksdienst voor Ondernemend Nederland, 2021;
Sanders & van Timmeren, 2018). Although the costs
of circular material and product use outweigh those of
other materials in the long term, it appears that the ini‐
tial additional cost is insufficiently quality‐enhancing to
convince customers, home or building owners. This has
a negative impact on the uptake of used materials, for
example in the construction sector in the Netherlands
(Oostra, 2020).
3. The IJburg Villa of Reused Wood as Central
Case Study
This article focuses on a central case study, a residen‐
tial villa in Amsterdam, the Netherlands. The project was
realised in 2017 and is a pilot project for the application
of reclaimed timber formwork in new building construc‐
tion. This case is of particular interest as it reuses the
timber formwork for load‐bearing elements. Thanks to
mechanical testing, performed by the authors, the case
provides insight into the capacity of the formwork and its
reuse potential for different building elements. The pre‐
sented method can be adapted to study the reuse poten‐
tial of other load‐bearing building products. In this case,
the discarded plywood formwork was applied both in the
outer walls and the floor, as part of the (load‐bearing)
structure. Figure 2 shows design drawings of the build‐
ing, pictures of the building during construction, and
pictures of after its realisation. As large quantities of
plywood formwork are discarded regularly, there is a
clear potential for its reuse, even on a larger scale.
The goal of this pilot project was to study the feasibility
of formwork reuse, especially for structural applications.
Urban Planning, 2022, Volume 7, Issue 2, Pages 81–96 85

Figure 2. Design, construction, and realisation of the villa with reused wood.
The irregularities in the formwork make it less suited
for visible finishing layers. Their high thickness of up to
17 centimetres, however, makes them well suited for
load‐bearing walls or floors.
At the construction site, the panels were put together
to form a four‐layer shell of walls and floors. The façades
at the end have a load‐bearing function. Between these
façades, the floors are supported by steel trusses. A steel
beam is required at various locations to bridge the dimen‐
sional differences of the plates. The wooden floors disap‐
pear under insulation material and a cast floor. On the
outside, the house is finished with vertical wooden laths.
Little of the wooden formwork elements is visible in the
final stage. By the time the house was finished, no traces
were left of the origin of the reclaimed materials.
4. The Timber Formwork
The purpose of this project is to investigate the reuse and
recycling potential of old formwork elements. The CO2
emission and energy consumption will be 522 kg CO2
for every cubic meter of plywood based on research by
Ashby (2013), Hill et al. (2018), and Danielson (2014).
The CO2emission factors of the materials are based
on processing, manufacturing, energy conception, and
transportation. The reuse of this material will result in a
Urban Planning, 2022, Volume 7, Issue 2, Pages 81–96 86

considerable reduction of the carbon footprint. This arti‐
cle looks at different opportunities based on the reuse
of old formwork of a Dutch concrete contractor special‐
ized in concrete production. A lot of timber formwork is
produced every day, but its reuse is limited. The maxi‐
mum amount of use cycles (as formwork) is determined
by the flatness of the shelf and the project characteristics
and could rise to a maximum of seven times. Therefore,
it is good to look at new opportunities for old form‐
work that cannot be used anymore. The formwork ele‐
ments are designed without making any structural cal‐
culations. The goal is to make formwork elements with
a completely flat and smooth surface in a cost‐efficient
way. When they are discarded, the elements are taken
apart and stored until they are pulverized (see Figure 3).
4.1. Composition of the Formwork Elements
As shown in Figure 3, the formwork elements consist
of pine beams that are connected perpendicularly to
other, load‐bearing pine beams using timber screws.
The beams are covered with plywood and lacquered to
keep the timber dry. A PVAC glue connects the plywood
to the beams. The shelf is fixed with additional staples.
Due to the irreversible connection of all these layers, the
formwork cannot be disassembled after being discarded.
4.2. Types of Formwork Elements
There are two types of formwork elements (see
Figure 4):
1. The A‐series consists of formwork elements with
full cross sections on large scale.
2. The B‐series consists of formwork elements on
sample scale. Within this B‐series, two types are
provided: (a) the BB‐series, consisting of a full
cross‐section sample, and (b) a BZ‐series consist‐
ing of just the shelf, without a connected beam.
Figure 5 presents the characteristics of series A, B,
and BZ.
5. The Mechanical Properties of Timber Formwork
As no structural analysis or mechanical testing is per‐
formed during the development of the timber formwork,
information about the mechanical behaviour is lacking.
For the application of the formwork in the construction
of the villa, it was, therefore, important to perform a
series of mechanical tests and evaluate the derived prop‐
erties. This section presents the results of this testing,
performed by the authors. Based on this, it reflects on
the role and importance of testing procedures and barri‐
ers to overcome.
5.1. Bending Test
The samples of the A‐series were tested with a 3‐ and
4‐point bending test. The 3‐point bending test is car‐
ried out to determine the maximum concentrated load.
The samples are positioned on two supports with a span
of 1800 mm. An equally distributed line load is increased
Figure 3. The basis material of old formwork at the depot (left) and its construction (right).
Figure 4. The two types of formwork elements: A‐series (left) consists of formwork elements with full cross sections,
B‐series (right) consists of formwork elements on sample scale.
Urban Planning, 2022, Volume 7, Issue 2, Pages 81–96 87

Property Average Average deviation
Length 1899 mm 0 mm
Width 998 mm 6.82 mm
Total height 153 mm 0 mm
Shelf height 60 mm 0 mm
Area of holes 926 mm2 718 mm2
No. of filled holes 18 14.4
Property Average Average deviation
Length 538 mm 0 mm
Width 248 mm 2.53 mm
Moisture content beam 15% 2.11%
Moisture content shelf 18% 3.40%
Mass 6.3 kg 0.18 kg
Property Average Average deviation
Length 538 mm 0 mm
Width 246 mm 2.83 mm
Moisture content shelf 23.0% 2.95%
Mass 5.2 kg 0.04 kg
Figure 5. The test samples represent different types of formwork, varying in shape and size. From top to bottom: The
A‐series consists of nine samples, each derived from one big shelf; the B‐series consists of seven samples, each derived
from one big shelf; final the BZ‐series consists of six samples, each derived from one big shelf.
with 4 kN per minute. The results are expressed by force‐
deformation graphs (Figures 6 and 7). All samples show
a significantly higher strength than required for residen‐
tial floors.
Further on, the needed force for a deformation of
7,2 mm is in the range between the minimum and max‐
imum calculated estimated force values of 2,28 kN <F
<25,7 kN. Therefore, it can be concluded that the load‐
bearing part does not only consist of the lower beam, but
the elements are also not fully connected.
The 4‐point bending test was carried out (see
Figure 7), in addition to the 3‐point bending test, on
the samples of the A‐series. A 3‐point bending test indi‐
cates the maximum concentrated load of the sample.
The place of failure will take place close to the middle of
the span, where the maximum bending moment occurs.
A 4‐point bending test, however, is preferred because
failure in this case occurs at the weakest spot. The cause
of this is that in the area between the loads, the bending
moment remains constant and the shear force is equal
to zero. The load capacity of the formwork elements is
compared to the requirement according to the Dutch
Building Act, which states a minimum concentrated resi‐
dential floor capacity of 3 kN. The allowed deformation
equals L/250 =7,2 mm. The samples in this experiment
are not loaded to failure like in the 3‐point bending test.
This test stopped when the deformation was a bit over
7,2 mm because strength characteristics were already
Sample Ultimate load
(kN)
A1D 25.4[1]
A3D 24.5
A4D 25.6
A6D 27.3
Average 25.8
Deviation 1.0
Sample Needed force for maximum
deformation (kN)
A1D 10.3[2]
A3D 11.6
A4D 11.6
A6D 12.3
Average 11.8
Deviation 0.3
0
0
–2
–4
–6
–8
–10
–12
–14
–16
–18
–20
–22
–24
–26
–28
–30
–2 –4 –6 –8 –10 –12 –14
Deformation [mm]
Force [kN]
–16 –18 –20 –22 –24 –26
A1D
A3D
A4D
A6D
minimum loading capacity
maximum deformation
Figure 6. Ultimate load (left), deformation (centre), and required force for maximum deformation (right) based on a 3‐point
bending test.
Urban Planning, 2022, Volume 7, Issue 2, Pages 81–96 88

Sample Needed force for maximum
deformation (kN)
A2D 18.7
A7D 17.0
A8D 17.5
A9D* 13.7[3]
Average 17.7
Deviation 0,6
0
0
–2
–4
–6
–8
–10
–12
–14
–16
–18
–20
–22
–24
–26
–28
–2 –4 –6 –8 –10 –12 –14
Deformation [mm]
Force [kN]
A2D
A7D
A8D
A9D
minimum loading capacity
maximum deformation
Figure 7. Deformation (left) and force for maximum deformation (right) based on a 4‐point bending test of A‐series samples.
known. The graphs reaffirm that all elements meet the
requirements for structural use.
Using the moduli of elasticity of the beam and the
shelf (determined in Sections 5.2 and 5.3, respectively),
the maximum span can be calculated. The uniformly dis‐
tributed load for a residential floor equals 2,5 kN/m2.
The maximum deflection of a residential floor is L/250,
according to the Dutch building code NEN‐EN 1995–1‐1.
Using this information, the maximum span can be calcu‐
lated as 3,07 m.
5.2. E‐Modulus of Spruce
The formwork consists of different parts like beams
of unclassified spruce and plywood. To measure the
e‐modulus of the different parts several tests have been
performed. For the spruce, an axial compression test was
done. To make an indication of the compressive stress,
the strength is assumed to be around the strength of
the lowest class: C14. With this assumed strength, the
expected load can be calculated, to have a good indica‐
tion of the result:
F= 𝜎 × A=14 ×45 ×74 =47 kN
Based on the section of the spruce (C14) it is assumed
that the applied force will be 47 kN and the modulus of
elasticity will be 7000 N/mm2. The three samples of the
C‐series have been loaded in compression. First, the sam‐
ples had to be prepared for the dimensions to be follow‐
ing the Eurocode. Therefore, the samples were sawn to
45 ×74 ×270 mm. These samples were loaded axially
parallel to the grain, so the direction of the grain in the
samples is equal to the longitudinal axis (270 mm).
The deformation, due to axial loading, is measured by
two LVDTs. Therefore, it is possible to determine if buck‐
ling occurs. The deformation is measured over a length
of 2L/3 which equals 180 mm. The fixed points of the
deformation indicators are placed L/6 =45 from the top
and 45 mm from the bottom, and these positions are
determined following the Eurocode. This test is executed
with a bench press, which is controlled by deformation,
so the deformation is constantly increased over time.
The speed of the deformation is equal to 0,5 mm/min.
Figure 8 shows the results of the test. Based on these
experiments the e‐modulus of the spruce is calculated
with Hooke’s law.
Based on the linear parts in the graphic, the average
modulus of elasticity is 7425 N/mm2. This is a plausible
answer because the modulus of elasticity of spruce is
7000 N/mm2on average.
5.3. E‐Modulus of the Shelf
The modulus of elasticity of the shelf is derived through
a 4‐point bending test with a span of 480 mm. The test is
executed with a bench press with a 2,0 mm/min deforma‐
tion. The results of the four experiments are represented
in Figure 9.
In general, this study uses a more statistical approach
to determine the load‐bearing capacity of the form‐
work. Such a study provides insight into the overall
performance of the formwork, which was entirely lack‐
ing. The advantage, in this case, is that large quantities
of formwork with similar load‐bearing capacity become
available for reuse every day. Moreover, since the func‐
tional life of the components is short, ageing of the mate‐
rial will be limited. Defects are similar and can there‐
fore be generalised in combination with visual inspection.
This is not the case for other types of reuse. Urban mining
often leads to small batches of materials that have been
Urban Planning, 2022, Volume 7, Issue 2, Pages 81–96 89

Sample E [N/mm 2]
C1 7760.2
C2 5809.3
C3 8704.5
Average 7424.7
Sample Ultimate load (kN) Strength (N/mm2)
C1 91.8 27.6
C2 75.6 22.7
C3 90.9 27.3
0
0
–10
–20
–30
–40
–50
–60
–70
–80
–90
–100
–0,2 –0,4 –0,6 –0,8 –1 –1,2 –1,4
Deformation [mm]
Force [kN]
–1,6
Indicator 1
Indicator 2
average
Figure 8. Results of the compression test of the spruce samples.
loaded under different conditions for long periods of
time. This requires a more individual assessment (includ‐
ing damage detection of all individual components) and
as such remains an important barrier to the reuse of load‐
bearing components. It is a subject for further research.
6. Reuse Potential and Component Redesign
Based on the case study research on timber reuse and
the analysis of the mechanical behaviour of the form‐
work samples, this section discusses the reuse potential
of timber formwork for new construction and studies dif‐
ferent redesign strategies that improve the potential for
selective dismantling.
6.1. Reuse Potential
The formwork elements have high strength and stiffness.
This could be useful for structural applications like floor
systems, façades, roofs, and structural walls. In these
cases, the timber would be covered and would not be
visible in the finished project.
6.1.1. Structural Residential/Utility Floors
The first possible application of the formwork elements
is using them as structural floor elements. The minimum
loading capacity, according to the Dutch building regu‐
lations, should be 1,75 kN/m2for residential use and
2,5 kN/m2to 5,0 kN/m2for utility use. Based on the test‐
ing results, the formwork elements are capable of resist‐
ing these live loads.
6.1.2. Façades and Roofs
Another application for the formwork elements is using
them as façade elements or roof elements. Façade ele‐
ments will be used as finishing panels and will not sup‐
port the main structure. When using the elements as
load‐bearing façades or roofs, it is important to take
live loads like snow and wind into account. These forces
could be as large as 2,12 kN/m2, depending on the height
and location of the structure.
6.1.3. (Structural) Inner Walls
Formwork elements could be useful as structural inner
walls because they have a high strength and stiffness
capacity. The space in‐between the load‐bearing beams,
underneath the shelf, could be used for sound and heat
insulation. By adding these insulation panels, the ele‐
ments will meet the requirements of the Dutch build‐
ing regulations.
6.2. Component Redesign
Now, the formwork elements have a lot of different
connectors, which are making the adaptability complex.
Sample E [N/mm 2]
B6Z 578.0
B8Z 1211.2
B10Z 402.2
B12Z 1135.2
0
0
–1
–2
–3
–4
–5
–6
–7
–9
–8
–10
–11
–12
–1 –2 –3
Deformation [mm]
Force [kN]
–4 –5
B6Z
B8Z
B10Z
B12Z
Figure 9. Force‐deformation graphs resulting from the 4‐point bending test of the shelf samples.
Urban Planning, 2022, Volume 7, Issue 2, Pages 81–96 90

The formwork elements can be reused within the pro‐
duction process of the concrete contractor by chang‐
ing the conventional connections into demountable con‐
nections. Nine alternative connections are discussed
to find better solutions with low cost, longer lifetime
and adaptability:
1. Glue
2. Timber dowels
3. Fixation
4. L‐connection
5. Z‐connection
6. Bottom magnets
7. Top magnets
8. Vacuum connections
9. Hoisting frame
6.2.1. Material Costs
Figure 10 and Table 2 compare the material cost of the
nine options by listing all required materials and estimat‐
ing their cost. All values are given for one element of 0,5
by 1,8m and are later expressed per m2. These total costs
are again split up into total connection costs and total
fixed costs. Since the total fixed costs are the same for all
options, it is easier to compare the total connection costs.
The analysis considers the cost per time unit, considering
the difference in lifespan between the shelf and beam
elements. The total lifetime of the beam is assumed to
be seven uses.
6.2.2. Factors of Cost and Revenues
The costs of the options for reuse are also partly deter‐
mined by production costs because certain acts require
more man‐hours than others. The production costs
of these specific methods are based on assumptions.
The conventional method has a time factor of 1. Other
methods are compared with the conventional method.
Table 2 shows the labour costs.
Figure 11 estimates the total lifetime cost by com‐
bining the material and investment cost and incorporat‐
ing the ease of use and workability for reuse. Ease of
use refers to the expected workability of the connec‐
tion option. Workable for reuse means that the element
can be adapted and reused for different purposes. This
includes how easy it is to saw the element. A waste factor
estimates the amount of formwork that would still be dis‐
carded. In Figure 11, the cost is represented as a ratio of
the cost of the conventional elements. The best option is
the one with a low value for the material, time and waste
factor, and a high value for the ease of use and the work‐
ability for reuse. Therefore, only values below one are
accepted (green) for the material, time, and waste factor
and only values above one for the ease of use and work‐
ability for reuse.
Plywood including beams
Pine mber beams
PVAc glue
L profile
Z profile
Dissolvable glue
Magnet
Magnet
Timber dowel
Steel strip
Vacuum system
rao
Life span beam
Life span shelf
1
7
7
1
7
7
1
7
7
1
7
7
50
350
7
70
490
7
70
490
7
70
490
7
4114.285714
28800
7
3085.714286
21600
7
Total cost
Element
Total connecon cost
Total fixed cost
Connecon cost / life me
Total cost / life me
Hollow tube secon
Hoisng system
Screws
Screws
Thickness 12 mm
74 x 58 m2
Wie houtlijm
Aluminium
Aluminium
—
25 kg
6 kg
40 mm
For magnet
6 systems
Info
Dimensions [m2]
Beam length
0. Convenonal
1. Glueing
2. Timber dowel
3. Connecon by fixaon
4. L-connecon
5. Z-connecon
6. Magnet connecon (boom)
7. Magnet connecon (top)
8. Vacuum connecon
9. Hoisng frame
25x25x2 mm, 2pcs
6 systems * 3 pcs
Length 100 mm
Length 20 mm
5.38
0.54
1.8
0.9
1.8
0.9
1.8
0.9
1.8
0.9
1.8
0.9
1.8
0.9
1.8
0.9
1.8
0.9
8
4
8
4
0.16
—
—
—

—
—
—
—
—
—
1.44
—
5.38
0.54
0.16
—
—
3.00

—
—
—
—
—
—
—
—
5.38
0.54
0.20
—
—
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0.09
—
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5.38
0.54
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—
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5.38
0.54
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2.52
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0.72
5.38
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2.52
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2.22
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2.58
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—
—
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0.09
5.38
0.54
0.16
—
—
—
6.74
—
—
—
—
7.66
—
—
—
23.92
—
0.64
—
—
—
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—
—
—
480,000.00
—
—
—
—
23.92
—
0.64
—
—
—

—
—
—
—
—
8,550.00
—
—
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/m2
/m
/L
/m
/m
/L
/pc
/pc
/pc
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/pc
—
/m2
Unit
/m2
/m2
8.36
1.62
6.76
12.96
6.20
6.76
12.19
5.43
6.76
22.76
16.00
6.76
2,143.64
2,137.50
6.14
120,006.14
120,000.00
6.14
10.36
3.60
6.76
6.76
—
6.76
10.09
3.33
6.76
6.90
0.14
6.76
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1.62
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3.33
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6.76
0.07
6.83
0.09
6.85
0.08
6.84
0.23
6.98
0.69
6.83
29.17
35.31
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/m
/pc
/pc
/pc
5.98
0.30
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0.70
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1.43
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0.02
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€
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€ 80,000.00
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Price
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€
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Figure 10. Material cost of the nine different connection options.
Urban Planning, 2022, Volume 7, Issue 2, Pages 81–96 91

Table 2. Labour cost for the nine connection alternatives.
Connection Option Time Factor Explanation
0. Conventional method 1 Reference value. Consisting of screwing secondary beams orthogonal
to main beams, gluing shelf to beams, and stapling the shelf
1. Gluing 1.5 Gluing shelf to beams
2. Timber dowel 1 Drilling holes in beam and shelf (200 mm in between distance), attach
dowel to beam using glue, attach beam + dowel to shelf using glue
3. Connection by fixation 2 Milling tapered groove in shelf, hammer beam in groove
4. L‐connection 1.5 Both profiles need to be screwed on shelf (200 mm in between distance)
5. Z‐connection 1.5 2 Z‐profiles need to be screwed on shelf and beams, including
L‐profile, have to be slided in
6. Magnet connection (bottom) 0.5 Steel strip needs to screwed on bottom of shelf
7. Magnet connection (top) 0.5 Steel hollow core beams need to be clamped underneath the shelf
8. Vacuum connection 0.1 Only placing frame on top of shelf
9. Hoisting frame 0.2 Mounting the frame onto the formwork elements
Connecon opon Material
factor [–]
Time
factor [–]
Ease of use Workable
for reuse
Waste
factor [–]
0. Convenonal method 1 1 1 1 1
1.20 1.5 1 3 0.3
0.81 2 0.5 2 0.7
0.82 1.5 2 0.2 0.3
0.82 1.5 0.5 0.5 0.35
0.82 0.5 3 1 0.5
0.83 0.5 2 2 0.5
4.21 0.1 3 3 0.2
0.82 0.2 3 3 0.2
0.82 1 1 3 0.3
1. Gluing
2. Timber dowel
3. Connecon by fixaon
4. L-connecon
5. Z-connecon
6. Magnet connecon (boom)
7. Magnet connecon (top)
8. Vacuum connecon
9. Hoisng frame
Figure 11. Total costs per lifetime expressed as a ratio of the cost of the conventional formwork system.
Urban Planning, 2022, Volume 7, Issue 2, Pages 81–96 92

0
Material costs Producon costs Usage problems Adaptability
problems
Waste
Convenonal mber formwork elements
10
20
30
40
50
60
70
80
Percentage [%]
90
100
110
120
130
140
150
1. Gluing
2. Timber dowel
3. Connecon by fixaon
4. L-connecon
5. Z.connecon
6. Magnet connecon (boom)
7. Magnet connecon (top)
8. Vacuum connecon
9. Hoisng frame
Figure 12. Visualisation of the total cost per lifetime for the different connection alternatives.
The results of Figure 11 are visualized in Figure 12.
The dotted line shows the conventional method, being
the reference value (100%). All bars lower than 100% are
assumed positive.
7. Conclusion
This article is centred around a pilot project that applies
reclaimed timber formwork for the construction of a new
villa. As these formwork elements are only used a couple
of times before being deemed unfit and discarded, they
possess a huge potential for repurposing in building con‐
struction. While irregularities may make them less suited
for visible building layers such as cladding, they do show
some promise as part of the (sub)structure. Their thick‐
ness and high strength are well suited for solid timber
construction. After all, most of the panels are discarded
due to excessive seams or markings and not because of a
failure in mechanical behaviour. To assess this behaviour,
the project entailed the rigorous mechanical testing of
the formwork panels, as presented in this article. As no
detailed guides or codes exist on the reuse of formwork
or even reclaimed timber, the Dutch Building Decree
requires such tests. They show that the formwork ele‐
ments have sufficient (remaining) load‐bearing capacity
to be applied in different structural applications.
Apart from the considerations about the structural
performance of the timber formwork, the pilot project
and studied cases provide some conclusions about mate‐
rial reuse. The main lessons are:
• Material reuse (and circular construction in general)
requires a systematic and integrated approach.
• This approach should be flexible to adapt to the
many unknowns related to material reuse.
• New types of collaborations are required, includ‐
ing the involvement of urban miners or other third
parties, but also the more active involvement of
contractors and engineers during the early design.
• Knowledge about circular construction and mate‐
rial reuse should be developed by all stakehold‐
ers in the value network, but also more horizon‐
tally in all layers of the involved companies or
organisations.
• There is a need for more uniform definitions,
guides, and codes.
• Using reclaimed materials reduces the embodied
energy of a building and often saves material costs.
Urban Planning, 2022, Volume 7, Issue 2, Pages 81–96 93

Logistics, planning issues, and additional efforts
during the design and construction can, however,
complicate the overall process. As such, the overall
project budget can, in many cases, not be consid‐
erably reduced.
While this article does focus on one specific case study,
its main contribution concerns the approach for assess‐
ment and redesign of the formwork. Reuse generally
comes with a lot of unknowns about the origins and
performance of reclaimed building components. This is
especially the case for load‐bearing products, whose per‐
formance ensures safety. This article shows a more sta‐
tistical approach to reuse based on the availability of
large amounts of similar non‐building components. This
shows a high potential for the repurposing of waste
streams. Urban mining and the reuse of building compo‐
nents come with additional challenges. Materials often
become available in small batches, making it less eco‐
nomically feasible to perform rigorous testing. Moreover,
such components have often been used for long periods
of time, sometimes in unknown conditions. This requires
more extensive damage detection. Further research on
the reuse of building materials can expand on this. Apart
from more technological research, it will be important to
map and develop solutions for the socio‐economic bar‐
riers that currently hinder material reuse. Studies con‐
ducted in the Netherlands show that despite the increas‐
ing availability and large application potential in the
construction sector, the use of reclaimed materials has
not yet managed to scale up or break through. Financial
and socio‐cultural factors play an important role in this,
such as habituation and the lack of additional comfort to
compensate for the higher initial cost. The central case
study of the circular house in Amsterdam shows that high
percentages of reuse are possible for the construction of
new buildings, but also depend on socio‐economic fac‐
tors and in this case the involvement and initiative of the
building owner.
Acknowledgments
This research was done thanks to the cooperation of the
Dutch concrete contractor Geelen Beton in Wanssum,
the structural engineering and design laboratory of the
Eindhoven University of Technology, and the realisation
of the Architectural villa in Amsterdam by Dr. ir. A. D. C.
Pronk and ir. R. Elerie. The testing results and sources are
owned by the authors, who realized them.
Conflict of Interests
The authors declare no conflict of interests.
References
Addis, B. (2012). Building with reclaimed components
and materials. Routledge.
Arora, M., Raspall, F., Cheah, L., & Silva, A. (2020). Build‐
ings and the circular economy: Estimating urban min‐
ing, recovery and reuse potential of building compo‐
nents. Resources, Conservation and Recycling,154.
https://doi.org/10.1016/j.resconrec.2019.104581
Ashby, M. F. (2013). Materials and the environment: Eco‐
informed material choice. Butterworth‐Heinemann.
https://doi.org/10.1016/C2010‐0‐66554‐0
Brancart, S., Vandervaeren, C., Paduart, A., Vergauwen,
A., De Laet, L., & De Temmerman, N. (2017). Trans‐
formable structures: Materialising design for change.
International Journal of Design & Nature and Eco‐
dynamics,12(3), 357–366. https://doi.org/10.2495/
dne‐v12‐n3‐357‐ 366
Brütting, J., De Wolf, C., & Fivet, C. (2019). The
reuse of load‐bearing components. IOP Conference
Series: Earth and Environmental Science,225.https://
iopscience.iop.org/article/10.1088/1755‐1315/225/
1/012025
Brütting, J., Vandervaeren, C., Senatore, G., De Tem‐
merman, N., & Fivet, C. (2020). Environmental
impact minimization of reticular structures made
of reused and new elements through life cycle
assessment and mixed‐integer linear programming.
Energy and Buildings,215.https://doi.org/10.1016/
j.enbuild.2020.109827
Charef, R., Ganjian, E., & Emmitt, S. (2021). Barriers for
a holistic asset lifestyle approach to achieve circu‐
lar economy: A pattern‐matching method. Techno‐
logical Forecasting and Social Change,170. https://
doi.org/10.1016/j.techfore.2021.120798
Danielson, D. T. (2014). Energy conservation program:
Energy conservation standards for automatic
commercial ice makers (Rulemaking Action No. EERE‐
2010‐BT‐STD‐0037). US Department of Energy.
https://www.energy.gov/sites/prod/files/2014/03/
f9/acim_ecs_nopr.pdf
Devlieger, L., Gielen, M., Little, S., Roy, A., & Dulière,
A. L. (2019). Building and demolition waste in the
UK. Architectural Research Quarterly,23(1), 90–96.
https://doi.org/10.1017/s135913551900006x
DGBC. (2020). Kringloopwinkel Noppes [Thrift store
Noppes]. https://www.dgbc.nl/projecten/
kringloopwinkel‐noppes‐30
Ellen McArthur Foundation, SUN, & McKinsey Center for
Business and Environment. (2015). Growth within:
A circular economy vision for a competitive Europe.
https://ellenmacarthurfoundation.org/growth‐
within‐a‐circular‐economy‐vision‐for‐a‐competitive‐
europe
Fivet, C., & Brütting, J. (2020). Nothing is lost, nothing
is created, everything is reused: Structural design for
a circular economy. The Structural Engineer,98(1),
74–81.
Galle, W., Cambier, C., Elsen, S., Lanckriet, W., Poppe, J.,
Tavernier, I., Vandervaeren, C., & De Temmerman, N.
(2019). Building a circular economy: Design qualities
to guide and inspire building designers and clients.
Urban Planning, 2022, Volume 7, Issue 2, Pages 81–96 94

Vrije Universiteit Brussel. https://www.vub.be/arch/
files/circular_design_qualities/VUB%20Architectural
%20Engineering%20‐%20Circular%20Design%20
Qualities%20(2019.12).pdf
Giordano, R., Serra, V., Demaria, E., & Duzel, A. (2017).
Embodied energy versus operational energy in a
nearly zero energy building case study. Energy Proce‐
dia,111, 367–376. https://doi.org/10.1016/j.egypro.
2017.03.198
Global Alliance for Buildings and Construction, Inter‐
national Energy Agency, and the United Nations
Environment Programme. (2019). 2019 global status
report for buildings and construction: Towards a
zero‐emission, efficient and resilient buildings and
construction sector. https://www.iea.org/reports/
global‐status‐report‐for‐buildings‐and‐construction‐
2019
Gorgolewski, M. (2008). Designing with reused building
components: Some challenges. Building Research
& Information,36(2), 175–188. https://doi.org/
10.1080/09613210701559499
Hill, N., Bonifazi, E., Bramwell, R., Karagianni, E., &
Harris, B. (2018). 2018 government GHG conversion
factors for company reporting: Methodology paper
for emission factors (Final Report). UK Department
for Business Energy & Industrial Strategy. https://
www.gov.uk/government/publications/greenhouse‐
gas‐reporting‐conversion‐factors‐2018
Hoxha, E., Habert, G., Lasvaux, S., Chevalier, J., & Le Roy,
R. (2017). Influence of construction material uncer‐
tainties on residential building LCA reliability. Journal
of Cleaner Production,144, 33–47. https://doi.org/
10.1016/j.jclepro.2016.12.068
Kawa, G. (2021). Design for re‐use guide: Reclaimed
wood and brick in façade architecture [Unpublished
Master’s thesis]. Vrije Universiteit Brussel.
Koutamanis, A., Van Reijn, B., & Van Bueren, E. (2018).
Urban mining and buildings: A review of pos‐
sibilities and limitations. Resources, Conservation
and Recycling,138, 32–39. https://doi.org/10.1016/
j.resconrec.2018.06.024
LETI. (2020). LETI embodied carbon primer: Supplemen‐
tary guidance to the climate emergency design guide.
https://www.leti.london/ecp
Mecanoo. (n.d.). Kaap Skil, Maritime and Beachcombers
Museum.https://www.mecanoo.nl/Projects/
project/51/Kaap‐Skil‐Maritime‐and‐Beachcombers‐
Museum
Myers, L. (2020). Recycled door frames clad this
kindergarten in Paris designed by BFV architects.
https://www.designboom.com/architecture/bfv‐
architectes‐creche‐justice‐paris‐ 11‐05‐2020
Oostra, M. (2020). Circulaire energietransitie in de
gebouwde omgeving, verkenning voor woonge‐
bieden [Circular energy transition in the building envi‐
ronment, exploration for residential areas]. Univer‐
sity of Applied Science Utrecht and Enpuls. https://
www.enpuls.nl/media/ibgfxpmt/onderzoeksrapport‐
circulaire‐energietransitie‐in‐de‐gebouwde‐
omgeving.pdf
Opalis. (n.d.). Museum van Jutters en Zeelui: een gevel uit
maritiem hout voor een maritiem museum [Museum
of “Jutters en Zeelui”: A façade from maritime
wood for a maritime museum]. https://opalis.eu/nl/
projecten/museum‐van‐jutters‐en‐ zeelui
Public Architecture. (2011). Design for reuse primer:
15 successful reuse projects within different sec‐
tors explored in‐depth.https://issuu.com/public
architecture/docs/design_for_reuse_primer_issuu
Rijksdienst voor Ondernemend Nederland. (2021).
Beschikbaarheid en gebruik secundaire bouw‐
materialen en producten [Availability and use of
secondary building materials and products]. https://
circulairebouweconomie.nl/wp‐content/uploads/
2021/12/Verkenning‐Beschikbaarheid‐en‐gebruik‐
secundaire‐bouwmaterialen‐en‐producten.pdf
Sanders, F., & van Timmeren, A. (2018, March 18–19).
Dutch circular cities by the energy of people: Post
PhD best practices research on Amsterdam and Rot‐
terdam citizen initiatives [Paper presentation]. Con‐
struction on Urban Future, Abu Dhabi, United Arab
Emirates.
Schut, E., Crielaard, M., & Mesman, M. (2016). Circu‐
lar economy in the Dutch construction sector: A per‐
spective for the market and government (Report
No. 2016–0024).RIVM. https://rivm.openrepository.
com/handle/10029/595297
Superuse Studios. (2009). Villa Welpeloo. https://www.
superuse‐studios.com/projectplus/villa‐welpeloo
Superuse Studios. (2020). KEVN—Expo, food & drinks.
https://www.superuse‐studios.com/projectplus/
kevn
Valenzuela, K. (2015). The circular pavilion/Encore
Heureux Architects. ArchDaily. https://www.
archdaily.com/778972/the‐circular‐pavilion‐
encore‐heureux‐architects
Wright, H. (2017). Europa building in Brussels by Philippe
Samyn. DesignCurial. https://www.designcurial.
com/news/europa‐building‐in‐brussels‐by‐
philippe‐samyn‐5782988
About the Authors
Arno Pronk graduated as an architect from the Faculty of Architecture, TU Delft, in 1994. After his stud‐
ies, he worked as an architect but also as a design technician. In cooperation with Professor Lichtenberg
(Eindhoven University of Technology) he developed and patented the slim line floor system. He has
two years of experience as an assistant professor at TU Delft and twenty years at Eindhoven University
of Technology, where he realised his PhD research on flexible moulding for fluid architecture.
Urban Planning, 2022, Volume 7, Issue 2, Pages 81–96 95

Stijn Brancart is an assistant professor of structural design at the Department of Architectural
Engineering and Technology at TU Delft. After graduating as an architectural engineer in 2013, he
finished his PhD research on rapidly and reversibly assembled structural systems in 2018, both at the
Vrije Universiteit Brussel. Focusing his work on circular construction, he then went on to work on the
Buildings as Materials Banks (BAMB) project and several smaller consultancy projects.
Fred Sanders recently graduated from the Department of Urbanism at TU Delft with his research on
bottom‐up resident initiatives for creating sustainable cities. He holds an MSc in civil coastal engineer‐
ing and an MBA from the Erasmus University of Rotterdam. He has twenty years of experience in real
estate management and public administration. He is a keynote speaker, journal editor, columnist, and
writer of youth novels, promoting sustainable and resilient initiatives.
Urban Planning, 2022, Volume 7, Issue 2, Pages 81–96 96