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Conference paper for European Steel Environment & Energy Congress 2014, 15-17 September, Teeside University UK
Reuse of structural steel: the opportunities and challenges
Danielle Densley Tingley1 and Julian Allwood2
1 Research Associate, UK INDEMAND Centre, Department of Engineering, The University of Cambridge,
email: dod21@cam.ac.uk
2 Principle Investigator, UK INDEMAND Centre, Department of Engineering, The University of Cambridge,
email: jma42@cam.ac.uk
Abstract: When debating the environmental impacts of steel product cycles, emphasis is
often placed on the recyclability of this metal. Whilst this is a benefit, particularly in terms of
material conservation and reducing raw material extraction, there is another, lower impact
option: material reuse. This paper explores the reuse of structural steel work. It uses
experiences from construction projects that have reused steel, or considered doing so, to
inform and lead the discussion, highlighting key research questions. The importance of the
source of reused steel is highlighted, and it is recommended that projects which aim to reuse
steel investigate potential sources at an early stage of the project to ensure supply. Other
challenges include re-certification of structural steel and the potential project cost increases as
a result of reuse. The opportunities from steel reuse are also discussed, including the potential
for expansion of existing businesses.
Keywords: reuse, steel, deconstruction, design, environmental impacts.
1 Introduction
The built environment consumes over half of global steel production. In a study of 2008 data,
Allwood and Cullen (2012) state that 14% of global steel produced is utilised in infrastructure
and 42% within buildings. The majority of this steel will be stored in the building stock for
the lifespan of the buildings. At the end of building life, the majority, where economically
feasible, will be recovered and recycled – undergoing an energy intensive process to form
new steel products. However, steel sections could be salvaged through the deconstruction of
buildings; this careful reversal of the construction process will result in salvage with
minimised damage, facilitating the potential for section reuse.
A report from Bioregional (unknown date) highlights the environmental benefits of reuse,
explaining that there is a 96% environmental impact saving from reusing steel sections
compared to procuring new steel. However, in spite of this, the recyclability of steel is still
considered a priority, with Sansom and Avery (2014) estimating the reuse of steel sections at
6%, compared to 93% being recycled. This suggests there are few incentives for structural
steel reuse and that there are barriers in place which hamper its reuse. Understanding the
challenges to reusing steel in construction projects is therefore crucial to progressing practice
in this area and reducing the life cycle impacts of steel. This paper highlights experiences
from practice, in addition to those from literature to assess the current barriers to reuse, as
well as emphasising the opportunities and potential benefits of steel reuse.
2 The barriers to structural steel reuse
In a review of barriers to reuse and deconstruction, Densley Tingley and Davison (2011)
show that there are a range of perceived barriers around steel reuse from the health and safety
of deconstruction through to the potential time constraints of incorporating the deconstruction
of an existing building into a project plan. The latter could be overcome if there was more
value placed on existing buildings and their inherent material stock. The reuse potential
would be identified earlier, giving additional time for deconstruction. There are some
technical challenges in existing buildings that arise from composite design; traditionally
Conference paper for European Steel Environment & Energy Congress 2014, 15-17 September, Teeside University UK
welded shear studs are used to connect metal decks to beams, which makes it difficult to
salvage floor beams without significant damage. New designs could utilise bolted stud
connections as demonstrated by Moynihan & Allwood (2014). However, it would be labour
intensive to deconstruct the resulting quantity of bolted connections, increasing costs; the
development of an automated deconstruction process could however reduce deconstruction
times. In addition to these technical barriers, three main practical challenges: sourcing of
steel, cost of steel reuse and re-certification, have been identified from discussions with
design teams and literature review, as outlined in the subsequent sections.
2.1 Sourcing Steel
The sourcing and procurement of reused steel is often a significant challenge in the reuse
journey. For projects, such as BedZED and the Baker Extension at the University of
Cambridge, which source individual steel sections for reuse, either specific section sizes to fit
within the existing structural design must be procured, or the design altered to fit the
available reusable sections. The former requires the design team to investigate the reuse
supply early in the design process to attempt to secure appropriate sections; this will likely
result in a mixture of reused and new steel due to a limited supply of reused steel. The latter
redesign option places an additional onus on the structural engineer, if reuse has been
identified at an early stage and detailed section design is left until reused materials are
sourced then this minimises additional labour costs. However, if redesign is required and the
structural engineer is on a fixed percentage fee, this could result in tensions between the
design team and client. When sourcing steel externally there is also a need to build longer
lead times into the project programme to ensure the steel is sourced, tested, re-fabricated
(where required) and delivered to site ready for construction.
An alternative scenario is those projects with an existing building on-site which contains
suitable components for reuse. This essentially provides a kit of parts which can be
incorporated into the new building, negating the potential problem of a reuse supply. In this
case, the available sections can be incorporated into the design at an early stage, eliminating
potential design and programme difficulties. This is the case for a small visitors’ hall being
designed by Smith and Wallwork Engineers, which is hoping to reuse 5 tonnes of steel from
an existing building on-site. Here, a greater barrier is the costs of deconstruction and reuse.
2.2 Cost implications for structural steel reuse
There is uncertainty around the costs of reusing steel. This is in part due to inexperience in
specifying reused steel. In addition, perceived risks of delays in the project programme and
construction can add to the cost. Where there are existing structures on-site, deconstruction
compared to demolition will take a small additional amount of time, which if planned for at
an early stage should have no impact on the project programme; there will however be
additional labour costs. In the case of the Smith and Wallwork Engineering project, it is
estimated 10 days are required to deconstruct the existing building, with additional time
required to re-fabricate the elements into new trusses. On the basis of labour, deconstruction
is quoted at £2,000 more than the demolition alternative. Further costs, almost equal to those
from the deconstruction labour, are added from the shot blasting of the salvaged steel. This
results in the reuse alternative being approximately 25% more expensive, a significant barrier
to reuse.
Conversely, evidence from Sergio and Gorgolewski (unknown date) on a case study of the
BedZED project, where 98 tonnes of steel were reused, shows that sourcing reused steel
components could lead to cost savings, due to the reduced cost of reused steel compared to
Conference paper for European Steel Environment & Energy Congress 2014, 15-17 September, Teeside University UK
new steel. It is therefore necessary to investigate and gather reuse costs for a wider range of
projects in order to gain a greater evidence base of the cost of steel reuse. This forms a key
part of further work.
2.3 Steel Re-certification
If steel is to be reused, someone must take responsibility for certifying its suitability. Some
clients and design teams are satisfied with a visual inspection of the components, as Sergio
and Gorgolewski (unknown date) state occurred on the BedZED project. In this case,
distortion, deflection and significant corrosion to the elements will be identified, as stated by
Addis (2006), highlighting the sections which are unsuitable for reuse. Where there are good
records and drawings showing the original steel use, the steel grade may be known,
facilitating reuse based on a visual inspection. If the steel grade is unknown, either the lowest
grade could be assumed, and the structure designed accordingly, or a tensile test can be
conducted to ascertain the steel grade. The latter would enable the reused steel to be used
more efficiently, reducing the quantity of excess steel incorporated into the building.
Conducting tensile tests requires small samples to be cut from the steel that is to be reused;
the yield strength of these will then be assessed. Until cheap mobile testing is developed, the
samples will need to be sent to a test house, there could also be a requirement for this to be
UKAS certified, as for the Baker Extension project. The time and additional cost for this
testing will need to be incorporated into the project and could in itself present a barrier.
Testing conducted for the Smith and Wallwork Engineering project was carried out at the
University of Cambridge Engineering Department, with a cost of £150, plus VAT, for three
samples. However, testing at commercial test houses may be more. The quantity of tests
required has also been debated, if the steel is from the same building it is likely to be the
same grade and thus a select sample could be tested. If the steel is sourced from a range of
projects, then in theory a sample should be tested from each project, which would lead to
increased costs. In a reused steel specification (2014), AECOM state that where samples are
confirmed as being from the same manufacturing batch, the contractor is required to test 6
samples for every 20 tonnes of steel. However, it is likely that different Structural Engineers
would have different requirements. These unknowns combined with the uncertain costs and
testing times can be a significant barrier for steel reuse.
3 What are the benefits of structural steel reuse?
The main motivation for engineers and clients who consider steel reuse is the environmental
benefits – the energy, carbon and other environmental impacts that are saved. Whilst these
environmental savings are significant, this motivation alone may not be sufficient to
overcome the challenges, particularly increased project costs. If the practice of reusing steel
increased, then much of the current uncertainty around specification, sourcing and
recertification would be removed. However, would removing the uncertainty and establishing
standard procedures also reduce the cost of reuse? This is key area for further research.
An increased demand for reused steel would also present several societal benefits: the
creation of specialist deconstruction contractors, and expansion of the current fabricators’
role into re-fabrication. Both businesses could also develop into stockholders and suppliers of
reused steel. Deconstruction requires more labour so should provide additional employment
compared to demolition, there may also be a need to upskill some of the workforce to
facilitate safe deconstruction of buildings. Increased deconstruction would not only provide
more reused steel, but would facilitate additional material salvage of other construction
materials; furthering the environmental benefits to the construction sector.
Conference paper for European Steel Environment & Energy Congress 2014, 15-17 September, Teeside University UK
In order to increase future ease of deconstruction, buildings designed now should be designed
for deconstruction and reuse. This should ideally be applied across building components and
would also provide some adaptability in-use, as well as giving easier access to upgrade
services. Design for deconstruction and reuse would also give potential for leasing schemes
for building structures, as leasers would have an easily recoverable asset. Mechanisms for
wide-spread implementation of design for deconstruction and reuse are being developed
within the RE-FAB project (2014).
4 Conclusions & Recommendations
This paper has identified a number of existing barriers to structural steel reuse, highlighting
three of prime concern. The re-certification process would be easier if an established
procedure was developed for structural engineers/contractors and endorsed by IStructE or
another industry body as recommended practice. Data is being gathered from design projects
to ascertain cost implications of steel reuse and removing this uncertainty should assist design
teams and clients in incorporating steel reuse into project budgets at an early stage. These two
factors would increase the demand for reused steel. Increased demand should help to drive a
deconstruction market therefore increasing supply, giving projects more reuse options.
Designing new buildings for deconstruction and reuse should also optimise future reuse
supplies.
The main recommendation to design teams and clients considering steel reuse is that sourcing
of appropriate sections should start at an early stage of the project. Local demolition
contractors could be contacted to ascertain if there are any suitable upcoming projects which
could supply the steel. This demand might encourage the contractors to explore
deconstruction as an alternative to demolition, leading to a better range of supply and an
expansion of their current business model.
5 References
Addis, W. 2006. Building with reclaimed components and materials: a design handbook for reuse and
recycling. Earthscan, London, UK.
AECOM, 2014. Performance specification for the re-use of structural steel. Issued to Cambridge
University Engineering Department via email to Danielle Densley Tingley, dod21@cam.ac.uk
Allwood, J. and Cullen, J. 2012. Sustainable materials: with both eyes open. Cambridge: UIT
Cambridge Ltd
Bioregional. Unknown date. Reclaimed building products guide: A guide to procuring reclaimed
building products and materials for use in construction projects. WRAP Guide.
Densley Tingley, D. and Davison, B. 2011. Design for deconstruction and material reuse. ICE
Proceedings: Energy, vol. 164, issue EN4, pp:195-204
Moynihan, M. & Allwood, J. 2014. Viability and performance of demountable composite connectors.
Journal of Constructional Steel Research, vol. 99, pp:47-56
RE-FAB project. 2014. RE-FAB – build better with less. Available at:
http://www.asbp.org.uk/news/detail/?nId=72 [accessed 30/07/14)]
Sansom, M. & Avery, N. 2014. Reuse and recycling rates of UK steel demolition arisings. ICE
Briefing in Engineering Sustainability, 167, ES3, June 2014.
Sergio, C. and Gorgolewsk, M. Unknown Date. BedZED Case Study. Available at: http://www.reuse-
steel.org/files/projects/bedzed/bedzed%20case%20study%205-5.pdf [accessed 14/07/2014]
