TDUK SupplyingTimber Issue 8 DIGITAL - Magazine - Page 68
———— THE "FOREST PUMP" ————
of substitution suggest that
on average one tonne of CO2
stored in wood represents
1.2 tonnes of CO2 avoided
through the replacement of
conventional materials. This is
the “low-hanging fruit” referred
to in the Rocky Mountain
Institute report.
Yes, wood has a relatively
small amount of embodied
carbon as a result of being
transported from the forest, cut
in the sawmill, then transported
to the construction site: i.e.
fossil fuels were burned in the
process of turning it from a
tree into a timber roof beam
for a house. However, that roof
beam could have been concrete
and the bene昀椀cial 昀椀gure from
a climate perspective is the
di昀昀erence between the CO2
emitted to make a wooden
beam and the CO2 emitted to
make a concrete beam. This
昀椀gure, this di昀昀erence, is a
measure of the substitution
e昀昀ect – a 昀椀gure as valuable in
SUPPLYING TIMBER
68
our endeavours to get to net
zero as the storage 昀椀gure.
Scale this up from city to city,
country to country, continent
to continent and we can drive
down carbon emissions from
the built environment via this
substitution role – yet more lowhanging fruit.
Calculations made by Michael
Ramage at the University of
Cambridge have shown that
erecting a 300m2 four-storey
wooden student residence in
SPRING 2025
↑
A graph showing
the carbon-capture
capability of trees as
they age; © Carbon
Neutral, Australia
The timber retro昀椀t
and extension at the
Technique Building,
London, achieved an
overall 1,709-tonne
reduction in
carbon compared
to a reinforced
concrete and steel
alternative.
↑
TIMBER KNOWLEDGE
may seem a statement of the
obvious – when we build with
timber, we do not use concrete
– but it is often missed when
carbon emissions are calculated
for building work.
In their insightful report Why
we need more trees in the UK,
Friends of the Earth spell out
this important contribution
that timber can make: “We
should also be increasing timber
use for house building and
construction, to reduce the use
of high-carbon materials such
as cement, mortar and brick”.
If you build your block of
昀氀ats out of wood rather than
concrete, you will replace
the concrete, a material that
was made by burning fossil
fuels, with a material that is
essentially the opposite. Wood
is a safe store of carbon that
has been taken out of the
atmosphere, not a material
whose manufacture has put
more CO2 into the atmosphere.
Recent studies on the impact
