timber in environmentally sustainable development
Timber as a Sustainable Building Material
Timber as a Sustainable Material
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www.timber.org.au
timber in environmentally sustainable development
Timber’s innate attractions
• Timber is a light, strong
material, used in
building structures for
millennia because it is:
–
–
–
–
Renewable;
Simple to manufacture;
Easy to use; and
Stable and safe.
• Importantly now, it is
also a store for carbon.
Woolmers pump house, Tasmania, 1841
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timber in environmentally sustainable development
Ease of manufacture
• Producing timber,
poles, veneer and
engineered timber
products is a relatively
simple, low capital
process.
• It uses few chemicals,
relatively little energy,
and produces few
pollutants.
Staff of a small veneer plant
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timber in environmentally sustainable development
Transport
• Logs weigh about 1
tonne/m3.They are
transported from the
forest in trucks.
• Most sawmills are
positioned near their
log supply, so
transport distances
are usually not long.
Logs on landing and being unloaded
Timber as a Sustainable Material
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timber in environmentally sustainable development
Producing sawn timber
• Logs are delivered
to site, stored and
then sawn.
• Because of the
character of logs,
only about 35% of
hardwood and 45%
of softwood logs are
converted to timber.
• The remainder is
sawdust or chipped.
Hardwood saw mills
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timber in environmentally sustainable development
Timber drying (or seasoning)
• The timber is then dried.
• This is either in the
open air or in a kiln.
• Air drying is slow and
very low energy.
• Air dried material can be
finished in the kiln.
• Kiln drying is faster.
Often, shaving and
sawdust fires the boilers
that heat the kilns.
Timber in racks for drying
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timber in environmentally sustainable development
Dry milling & sale
• Dry timber is graded
and sorted.
• It can then be
moulded to different
shapes or sold for
further processing.
• Often, no other
processes are
necessary before it
can be used.
Quality control in a dry mill
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timber in environmentally sustainable development
Veneer manufacture
• Logs for structural or
decorative veneer
are delivered to site.
• It may be sawn into
flitches and heated
in water before
peeling or slicing.
• Unused section of
log are often sawn
into timber.
Stacking veneer from a slicer
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Veneer drying and grading
• Once sliced or
peeled, the veneer is
dried in a dryer,
before being graded.
• After grading, the
veneer is trimmed
and can be laid up
into sheets.
Grading veneer
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Engineered products
• Plywood and LVL
are layers of peeled
veneer glued and
pressed together in
industrial equipment.
• Nail plating of
trusses requires a
simple hydraulic
press and a work
space.
Pressing nail plates
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Glue lamination
• Glue laminated
material is sawn
timber, planned to
give a smooth edges
and adhered with a
waterproof glue.
• Transport is the only
effective limitation on
the size of glulam
members
Prefabricating glulam beams
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Refurbishment & recycling
• The ease of initial
manufacture translates
to an ease in:
– construction
– refurbishment; &
– recycling,
• Large sections, joinery
and fitting are often
recycled. Smaller
sections may be reused.
Timber as a Sustainable Material
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timber in environmentally sustainable development
Carbon storage in forests
• During photosynthesis trees absorb CO2
from the air, stores the carbon in woody
tissue and give off oxygen.
• To produce 1 Kg of wood, a tree:
– absorb in 1.47 Kg of CO2; and
– returns 1.07 Kg of oxygen to the
atmosphere
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timber in environmentally sustainable development
Carbon stored in forests
• In 2001, Australia's
plantations and managed
forests stored a net 22.7
million tonnes of carbon
dioxide equivalent.
• So, they stored more than
half of the greenhouse
gases emitted by all the
passenger cars in Australia
that year.
Timber as a Sustainable Material
50% of CO2
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timber in environmentally sustainable development
Carbon stored in building
• When logs are
converted to timber
and other wood
products, the carbon
from the tree is stored
in the products.
• Timber buildings are
carbon stores.
Bus stop, Kings Meadow, Tasmania
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timber in environmentally sustainable development
Current greenhouse accounting method
• The current greenhouse accounting method
calculates decomposition of forest products
using product service life pools:
–
–
–
–
Pool 1 - service life 3 years - paper products
Pool 2 - service life 10 years - pallets, palings
Pool 3 - service life 30 years - kitchen furniture
Pool 4 - service life 50 years - poles, construction
materials
• At the end of each pool life, the carbon is
assumed to return to the atmosphere.
• This may overestimate emission considerably.
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timber in environmentally sustainable development
Alternative method
• Establish five service life pools of 3, 10, 30,
50 and 90 years
• Establish three age groups within each
service life pool - Young , Mid, and Old
• Wood products then progress through each
age group with one of five alternatives:
–
–
–
–
Progress to next age pool
Leave pool and enter landfill pool
Leave pool and enter recycling pool
Leave pool and their carbon is emitted to
atmosphere
– Long-term storage beyond pool service life
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timber in environmentally sustainable development
Alternative Method
Recycle
Landfill
Decomposition
Atmosphere
Longer-term storage
Leaves
pool
Bioenergy
Atmosphere
Leaves
pool
Carbon
from
forest
Young age
group of
pool
Timber as a Sustainable Material
Mid age
group of
pool
Old age
group of
pool
Leaves
pool
Product to
permanent
storage
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timber in environmentally sustainable development
Alternative Method
• The alternative method better reflects
what happens to wood products.
• The effect on calculated emissions is
shown on the following two slides.
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timber in environmentally sustainable development
Fate of Carbon in W ood Products - decompositi on over
servi ce lif e, no age gr oups wi thin pool s
3 00 0 0 0
C arbon from forest
C arbon in p rodu ct pools
2 50 0 0 0
Carbo n , kt
2 00 0 0 0
1 50 0 0 0
1 00 0 0 0
2004
19 9 9
1 9 94
1 9 84
1 9 79
1 97 4
1 96 9
1 9 64
1 95 9
1 95 4
19 4 9
19 4 4
0
1989
50 0 0 0
Ye ar
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timber in environmentally sustainable development
F ate o f C arbo n i n W oo d P ro d uc ts - Ag e G ro up s W ith i n P o ol s, w ith
La nd fi l, R e cyc li n g an d B io en e rg y in cl u de d
3 00 0 00
C arb o n f ro m f o re s t
To t al st o rag e in wo o d p ro d uc ts a nd
la nd f ill p o o ls
C arb o n in land fill p o o l
2 50 0 00
C arb o n in wo o d p ro d uc t p o o ls
C arb o n in b io e ne rg y p o o l
C a r bo n , k t
2 00 0 00
1 50 0 00
1 00 0 00
2 0 00
19 9 2
1 9 84
19 7 6
1 9 68
19 6 0
1 95 2
0
1944
50 0 00
Ye a r
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timber in environmentally sustainable development
Alternative Methods - Conclusion
• A life cycle approach, including
consideration of the use of residues,
storage in service, recycling and
disposal to landfill has the potential to
significantly decrease the contribution
from wood products to Australia’s
estimates of greenhouse gas emissions.
Timber as a Sustainable Material
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timber in environmentally sustainable development
Timber impacts compared to other materials
• Timber is only one of
a range of materials
available for
construction.
• All material have an
impact and it is
possible to compare
their use in
manufacture and
use using LCA
techniques.
Shear connector positions in a glulam beam
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timber in environmentally sustainable development
Timber uses less fossil fuel to make
500
400
435
300
200
100
0
1.5
2
35
Fossil fuel energy (MJ/kg)
Rough sawn timber
Timber as a Sustainable Material
Concrete
Steel
Aluminium
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timber in environmentally sustainable development
Timber store carbon. Others release it
6000
5000
5320
4000
3000
2000
1000
15
120
250
0
0
0
Carbon released (kg/m3)
Rough sawn timber
Timber as a Sustainable Material
Carbon stored (kg/m3)
Concrete
Steel
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timber in environmentally sustainable development
Embodied Energy of Materials
18
16
14
12
Steel
10
8
6
4
2
0
Concrete
Glass
Wood
Effect
Comparative Energy Use in an idealised structure where 4
materials have an equal contribution to the structure
derived from “Factor 4- Doubling Wealth - Halving the Resource Use:
Timber as a Sustainable Material
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timber in environmentally sustainable development
Timber has lower embodied energy
Timber as a Sustainable Material
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timber in environmentally sustainable development
Timber has lower ecological profile
Timber as a Sustainable Material
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timber in environmentally sustainable development
Timber elements have lower impact
• Embodied energy of differing window frames
Timber as a Sustainable Material
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timber in environmentally sustainable development
Timber as a Sustainable Material
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timber in environmentally sustainable development
Timber as a Sustainable Material
www.timber.org.au