Simulation of CO2 Reduction Effect with Timber Use by 2050
Research Institute
(Yuko Tsunetsugu (Department of Wood Engineering)
Mario Tonosaki (Department of Wood Properties)
Forestry and Forest Products Research Institute
Background and Purpose
To prevent global warming, it is necessary to reduce atmospheric CO2 and CO2
emission from fossil fuel. Because tree absorbs CO2 during its growth, and this absorbed
CO2 is not released into atmosphere. It can be called “Effect of carbon storage”.
Compared with other construction materials, less energy is required during process. It
also can be thought as “Energy saving”. Moreover, as a fuel, wood can reduce demand
for fossil fuel. So it can be called “fossil fuel alternative”. These three effects all play
important roles in CO2 reduction.
By 2050, Japan is trying to reduce CO2 emission by 60%~80% of current emission
and shift to a “low-carbon society”. For this target, this study simulated how much effect
of CO2 reduction can be obtained with timber use by 2050.
Achievements and Features
Carbon storage effect by timber
Timber used as column and beam of a house made of wood absorbs CO2 during tree
growth. If houses made of wood increases, CO2 absorption will increase and reduce CO2
emission into the atmosphere. Besides houses made of wood, paper and timber used in
other construction and furniture have the same CO2 absorption function. How much
carbon is stored in Japan?
For example, there are 10 buildings in a town. Next year, if two new buildings are
built and one building is demolished, a total of 11 buildings are left at the end of next
year. A model, which will calculate the stocks of construction, furniture, and paper from
the annual amounts of production and disposal, was built in this way. With this model,
the study estimated production of future construction, furniture, and paper by 2050
based on population and economic prediction.
If wooden buildings increase…
Even for equal-sized buildings, 10 times of the timber in non-wooden buildings are
used in wooden buildings. Also in furniture, more wood is needed. So by using wood in
construction and furniture, more CO2 can be stored. Compared with steel and concrete,
building one beam with wood requires less energy. So completing wooden buildings
requires less energy (energy-saving effect, Table 1). Thirty-five percent of construction
and furniture being completed every year, currently, are wooden construction. The
current scenario and promotion scenario when the rate of wooden construction becomes
70% by 2050 were compared (Figure 1).
Fossil fuel alternative effect by using remainder wood
If used as a biomass fuel after making much use of the timber, carbon emission
derived from fossil fuel can be reduced. The energy saving effect is calculated here by
using all the timber obtained from scrapped construction and furniture annually.
Energy saving for using remainder wood during construction and furniture making is
also calculated.
More Use for wood!
Because construction, furniture, and paper will decrease by 2050, the carbon storage
will gradually decrease based on the current scenario, become negative after 2016, and
the result is shown (Figure 2). As a whole this will be absorbed by the total fossil fuel
alternative effect, but will also decrease toward emission by degrees. For the promotion
scenario, carbon storage is about 1,000,000 tons (carbon conversion, same as below) for
non-wooden buildings. If we change to wooden buildings, the energy saving effect is
about 2,000,000 tons. In addition, the fossil fuel alternative effect is about 2,500,000
tons by using remainder wood. So the total CO2 reduction is estimated at about
5,500,000-6,000,000 tons. This amount is about 1.5% of the total Japanese emission in
2007. In order to realize a low carbon society, it is important to make active use of
timber, which is a recyclable resource.
This research is the result of a project of the Global Environment Research &
Technology Development Fund, Ministry of the Environment: “S-3 Low-carbon society
scenario toward 2050: scenario development ant its implication for policy measures”.
Table 1. Energy of material production for construction (C ton/m2)
Wooden
SRC
RC
S
Non-wooden
building
building*
building*
building*
building**
0.156
0.133
0.059
0.085
0.095
Reference: Kanji Sakai et al., Kankyo System Kenkyu, 25:525~532, 1997.
* SRC: steel reinforced concrete, RC: reinforced concrete, S: steel
** Average value weighted by area ratio of various non-wooden buildings with less than
3 stories
Figure 1. Scenario of construction building starts by 2050
(Left) Current scenario: wooden buildings account for 35% of total building starts.
(Right) Promotion scenario, wooden buildings by 2050 account for 70% of total building
starts.
Each scenario assumes that the total building starts is reduced with the decrease of the
population and number of households.
Figure 2. CO2 reduction effect by timber use (carbon conversion)
(Left) Current scenario: production of wooden buildings and wood furniture account for
35% of total production.
(Right) Promotion scenario: production of wooden buildings and wood furniture until
2050 account for 70% of total production.
The energy saving effect of the promotion scenario is assumed to be the value when the
current scenario is 0.