Mechanical properties of UK grown timber – improving quality and reducing waste
Submitting Institution
Edinburgh Napier UniversityUnit of Assessment
Electrical and Electronic Engineering, Metallurgy and MaterialsSummary Impact Type
EnvironmentalResearch Subject Area(s)
Environmental Sciences: Environmental Science and Management
Agricultural and Veterinary Sciences: Forestry Sciences
Engineering: Resources Engineering and Extractive Metallurgy
Summary of the impact
As a result of Edinburgh Napier University's contribution to the
`Strategic Integrated Research in Timber' network, the UK forest
industries (from tree breeders to timber engineers) and policy makers are
much better informed about the key characteristics of UK-grown timber
(particularly the principal commercial species, Sitka spruce) and how
these characteristics are influenced by tree growth, silviculture and
processing decisions.
Information has been provided to support: improved grading of timber;
segregation of logs and trees for optimal conversion; refocusing the UK
tree breeding programme for future wood quality; improvement of European
Standards for timber grading; and improved perception of UK-grown timber
for construction use. These combine to produce impact through reduced
wastage (material and energy) and creation of wider markets for UK-grown
timber.
Underpinning research
The UK forest and timber industries (excluding furniture) have an annual
turnover of £8.5billion. Conifers account for half of the UK woodland, of
which half is Sitka spruce, the main commercial species (72% of which is
in Scotland). Softwood accounts for ~95% of timber harvested, of which 1/3
goes to construction markets. However, the UK imports ~60% of the
(£1.3billion value) sawn softwood it consumes and the construction
industry (notably timber frame house building) has used mostly imported
timber. The aim of the research in this case study has been to improve the
profitability of UK forestry and sawmilling by increasing the use of UK
timber in construction by improving the quality of graded timber and
reducing wastage in the value chain.
The Strategic Intergraded Research in Timber (SIRT) network is a
collaboration between Edinburgh Napier University (sawn timber level), The
University of Glasgow (wood anatomy level) and Forest Research (tree
level) which has been running since 2003 — initially with funding from the
Scottish Funding Council and later with funding (at Napier) from industry,
Forestry Commission, Scottish Enterprise, Scottish Forestry Trust, and the
European Regional Development Fund. Impact (priority for these funders)
was built into the research from the outset.
This case study is for the research undertaken at Edinburgh Napier
University (by full time research staff) into the quality of UK-grown
timber for construction — principally Sitka spruce but also Douglas-fir
and larch (currently extending into other species). The research covers
the extent of between-forest, between-tree, within-tree and within-timber
variation of wood properties and links those properties to tree growth,
silviculture and processing decisions in order that the suitability of UK
timber for construction can be improved in the short term (via processing
and segregation) and the longer term (through silviculture and tree
breeding). The research involved bending tests, non-destructive testing,
tree measurement and statistical modelling. The key findings of the
research that produced impact are:
F1) That UK-grown spruce is limited in strength grading by
stiffness, rather than strength or density (as previously believed), with
statistical distributions of properties quantified and correlated with
commonly used grading indicators.
F2) That small changes in the resource stiffness would have a
major impact on future machine grading settings (and production yield),
and that current European Standards for strength grading exacerbate this
unnecessarily (in the way characteristic values are calculated from test
data).
F3) The realisation that tree breeding programmes need to consider
stiffness (in addition to existing focus on improved stem form, growth and
density) with some evidence of selection having reduced stiffness.
F4) That within-tree and within-forest variation exceeds
between-UK-forest variation, with influence of spacing, latitude, and tree
age quantified.
F5) That the juvenile core wood currently governs quality of
structural timber due, largely, to high microfibril angle (orientation of
cellulose crystals with the wood cell wall) which results in low stiffness
and drying distortion.
F6) Understanding of the application of acoustic tools for quality
assessment of trees and logs, and their limitations has been improved
(previously it was believed these tools do not work for UK spruce due to
its knottiness).
F7) That it is not possible to segregate logs to reduce drying
distortion of sawn timber, but that cutting patterns could be used to
reduce distortion
Key researchers (Napier):
Dan Ridley-Ellis, Principal Research Fellow (April 2003 - present)
Stefan Lehneke, Research Technician (April 2006 - present)
John Moore, Principal Research Fellow (January 2006 - February 2011)
Paul McLean, Senior Research Fellow (November 2011 - June 2013)
References to the research
Researchers who have been employed by, registered as PhD students at, or
seconded to Edinburgh Napier University are underlined. Researchers named
above in bold.
McLean, J., Evans, R., Moore, J. R.. (2010).
Predicting the longitudinal modulus of elasticity of Sitka spruce from
cellulose orientation and abundance. Holzforschung 64:495-500.
Moore, J.R., Achim, A., Lyon, A, Mochan, S. and Gardiner,
B. 2009. Effects of early re-spacing on the physical and mechanical
properties of Sitka spruce structural timber. Forest Ecology and
Management, 258: 1174-1180.
Moore, J.R., Mochan, S., Brüchert, F., Hapca,
A.I., Ridley-Ellis, D.J., Gardiner, B.A., and Lee,
S.J. (2009). A comparison of four different Sitka spruce genotypes growing
in the United Kingdom. Bending strength and stiffness of structural
timber. Forestry, DOI:10.1093/forestry/cpp018
Moore, J.R, Gardiner, B., Ridley-Ellis,
D., Jarvis, M., Mochan, S. & Macdonald, E. (2009) "Getting the most
out of the United Kingdom's timber resource". Scottish Forestry, Volume
63, number 3, pp 3-8
Moore, J. R., Lyon, A. J., Searles, G. J.,
Lehneke, S. A., Ridley-Ellis, D. J. (2013)
Within- and between-stand variation in selected properties of Sitka spruce
sawn timber in the United Kingdom: implications for segregation and grade
recovery. Annals of Forest Science. Volume 70, Issue 4, pp 403-415. DOI
10.1007/s13595-013-0275-y
Funding for research at Edinburgh Napier University has come largely from
donations for the overarching research programme, but with some grants
associated with specific PhD projects. e.g. "Sitka Spruce Segregation and
Cutting" from the Scottish Forestry Trust, 2008-2012, £10k, PI: John
Moore. The student, Greg Searles was awarded the Scottish Woodlands
Student Excellence Award for 2012-13 due to the industrial relevance of
the work.
Details of the impact
Overview
Impact has been achieved in four areas: economic impact for industry;
policy at UK and Scottish Government level; improvement of European
Standards; and raising awareness and understanding of timber-related
issues among the public. The economic impact comes with environmental
impact as profitability for UK forest industries means more forest
planting, substitution of non-renewable construction materials and reduced
timber miles.
Primary beneficiaries and routes to impact
The primary beneficiaries are UK timber growers and sawmillers. The
research has been directed by their needs from the establishment of SIRT
in 2003. An industry sponsor board meets quarterly to discuss the research
work and the network has conferences for sponsors (at least annually) and
industry generally (also at least annually) for knowledge transfer and set
the research agenda to real industry problems. Sponsor organisations
include the largest UK sawmilling and forestry companies as well as the
Confederation of Forest Industries. Projects have, to varying degrees,
been co-funded by industry, in many cases, involving industry providing
substantial in-kind support through donation of material, facilities and
staff time for discussion; the primary route for knowledge transfer and
impact. Knowledge transfer also takes place though events for specific
projects (at least annually) and industry magazines.
Economic and policy impacts
It is not possible to provide a precise value of impact because timber
markets are sensitive to international exchange rates and trends in the
construction sector meaning that the economic differential between graded
timber and rejects (which go to other markets) is volatile. Production
costs are commercially sensitive, but in 2010, during the construction
recession, it was estimated by industry that the cost of 1% reject
(construction timber sawmilling across the UK) was approximately
£300-500k. A figure of £400k per percent rejects has been used for the
following value assessments.
The project underpinned development of settings for the latest generation
of X-ray and acoustic grading machines, which has enabled UK (and Irish)
sawmills to use these machines. These settings have resulted in reduced
reject rates for British spruce. These settings were approved for
industrial use by the CEN (European Standards) committee in Spring 2011
and used data collected in the preceding 18 months. Estimated worth across
UK sawmillers: £400-£800k per annum [from F1].
UK sawmilling industry now producing higher grades from UK spruce with no
increase in reject due to these improved machine settings (above).
Industry is only now (summer 2013) putting the combined grading into
practice (it requires changing production lines). It is too early to
estimate worth, but this is already challenging the misconception (held by
sawmills, merchants and end users) that UK timber cannot achieve such
grades — improving perception as a construction material [from F1].
Dan Ridley-Ellis is now playing an active role in timber grading
committees at UK (since 2009) and CEN level (since 2011), improving
standards and representing the interests of the UK. The value of this lies
in preventing problems in standards impacting on UK sawmilling which could
easily cost millions of pounds per year. For example, arguing against a
mandatory adjustment on measured stiffness (in standard EN384) (that was
shown, thanks to research undertaken, not to work) has saved future
grading settings moving from the currently low proportion of machine
rejects (~2%) up to an unviable 20-30% [from F2].
Grading standards work and underpinning research has also allowed the
University to provide confidence for UK sawmillers in the grading
technology they are currently investing in, and advise on how it can be
best used (2009-current). "This should have significant financial
impact in the long-term" (Named Timber Consultant #1) [from F1,
F2, F5, F6].
UK tree breeding programmes have refocused to include stiffness (~2011).
The impact is to prevent a future increase in rejects (estimated 3-10% or
£1-4m/year) [F1, F2, F3 and employing F4, F5
and F6] The research also allowed advising of policy
makers (via Forestry Commission) on future species planting following
recent outbreaks of tree diseases.
UK industry now using acoustic tools for log segregation and processing
decisions. Estimated worth of 1% reject or £400k/year [from F6]
There is added impact in involving industry directly with research (an
ongoing process between 2008-now) and encouraging the various growers and
sawmillers to come and work together (at least quarterly) on common
challenges, and focus their attention on future market opportunities that
research enables — which has resulted in ongoing industry funding.
The research underpinning these impacts is the result of our close
partnership with Forest Research and Glasgow University — especially
linking of forest and tree level research (led by Forest Research) to the
wood properties research (led by Edinburgh Napier University). Forest
Research is part of the Forestry Commission — a devolved government
department in England and Scotland.
Wider impacts -environmental and social
By supporting the UK forest industries and the use of timber (a
sustainable, renewable material) in construction, and reducing wastage of
energy and materials, the research provides benefit to the environment and
the UK economy — especially in rural areas. This is the reason why the
research is funded by Forestry Commission and Scottish Enterprise.
The ultimate beneficiaries of the research are the public who use timber
products and benefit from UK forests (the environmental and social
benefits of which are well documented). Public engagement with aspects of
this research have been enabled through events- producing social impact in
raising awareness of wood science and environmental matters. They include:
Wood biomechanics in 3D, Royal Botanic Gardens Edinburgh, 18 July and
21/22 August 2010 (~600 people — general public)
Fantastic Forests, Royal Botanic Gardens Edinburgh, 14/15 April 2011
(~1200 people- general public)
Stand-up comedy by researcher Dan Ridley-Ellis on BBC Radio Scotland
(MacAulay and Co 25 May 2012, reach unknown) and Bright Clubs Edinburgh,
Glasgow, Dundee, Stirling, Aberdeen and London performing to a total of
~1500 people over 13 shows (general public). (July 2011-Ongoing)
Sources to corroborate the impact
5.1) Named Timber Consultant #1 [All claims — but especially
those relating to industry]
5.2) Named Timber Consultant #2 [All claims — but especially
those relating to industry]
5.3) BSW Timber Ltd (Director) [All claims — but especially those
relating to industry]
5.4) Forest Research (Research Scientist) [All claims — but
especially those relating to UK breeding programme and timber growers]
5.5) Forestry Commission Scotland (Timber Development Policy Adviser)
[All claims]
5.6) "The Scottish Forestry Strategy: Implementation plan (2012-16)
and progress report (2012-13)", Forestry Commission Scotland 2013 http://www.forestry.gov.uk/sfs
[evidence of the research linking into policy development for economic
benefit]
5.7) Timber Development Programme summary reports 2011-12 and 2012-13,
Forestry Commission Scotland. (not currently online but copies available
on request)
[evidence of the research linking into policy development for
economic benefit]
5.8) Minutes of the Scottish Forest & Timber Technologies
Leadership Group
http://www.forestryscotland.com/about-us/sftt-leadership-group
[evidence of the research linking into policy development for economic
benefit]
5.9) Davies, I., "Sustainable Construction Timber — sourcing and
specifying local timber" (2009) Forestry Commission Scotland. ISBN
978-1-904320-07-4
http://www.forestry.gov.uk/pdf/fcfc152.pdf/$file/fcfc152.pdf
[example of knowledge transfer through Forestry Commission with industry
engagement]
5.9) SIRT TIMBER RESEARCH PROJECTS "A catalogue of projects
demonstrating the range of work being conducted within the SIRT and
related programmes" February 2013
http://www.napier.ac.uk/forestproducts/centres/woodstudio/wpig/ResearchNetworks/SIRT/Documents/SIRT%20Abstracts%20booklet.pdf
[As the title describes. This was produced for industry readership]