Reuse of structural CLT elements: Assessing the impact of inter-element joint solutions on the reuse potential and environmental impact of a load-bearing wall panel
Typ
Examensarbete för masterexamen
Program
Industrial ecology (MPTSE), MSc
Publicerad
2022
Författare
Ljunge, Jonna
Nerhed Silfverhjelm, Helena
Modellbyggare
Tidskriftstitel
ISSN
Volymtitel
Utgivare
Sammanfattning
The construction sector is a significant contributor to many of our current environmental
challenges. To make the sector more sustainable, it is important to increase
the use of renewable materials and implement circular strategies such as the reuse
of building components. For reuse to become practically possible, the elements of a
building must be easily removable without causing them damage. The joints connecting
the building elements are thus vital for enabling reuse. The aim of this study
is to assess how the choice of inter-element joint solution affects the reuse potential
and environmental impact of reusing a load-bearing CLT wall panel.
A literature review is performed to analyse how joint solutions impact the reuse
potential of a structural element. The limited amount of existing research on the
topic was found to be too general to be of sufficient relevance for CLT construction,
in addition to being inconsistent in including important factors determining reuse
potential. A new framework for analysing reuse potential is therefore developed in
which joint solutions for a CLT wall panel are categorised according to the direction
of removal they enable and whether their removal causes damage to a panel.
The reuse potential framework is further used as a basis for developing scenarios
for reusing a wall panel over multiple cycles. Two types of reuse are distinguished
between in the scenarios: reuse between buildings (disassembly) and reuse within
a building (adaption), forming the basis of an LCA of the environmental impact of
multiple cycles.
By analysing the direction of removal and potential damage caused to a panel, it is
found that common joint solutions for CLT wall panels offer a range of reuse potential
when assessed individually. However, there is currently a lack of joint combinations
that fully enable reuse of a wall panel both through disassembly and adaption. To
ensure more flexibility in how a panel can be reused, it is necessary to opt for other,
or develop existing, solutions to increase the overall reuse potential. Additionally,
the choice of joint solution affects the number of possible reuse iterations (use cycles)
which is a key factor in determining the potential environmental impact reduction
of a reused panel compared to the corresponding linear pathway. The largest impact
reductions are found in the intermediate use cycles, suggesting that joint solutions
enabling many intermediate cycles might create the largest reuse incentive.
Beskrivning
Ämne/nyckelord
reuse, reuse potential, CLT, timber structure, joint, direction of removal, Design for Adaption, Design for Disassembly, circular economy, multiple-cycle LCA