Research Trends and Results

Approaches for assessment of CO2-reduction effect byusing low-carbon technology
KADOYU Katsunori, HeadKANDA Taro, Researcher
SUGABAYASHI Keita, Guest Research Engineer
Environment Department Road Environment Division(Keywords) Global warming, Low carbonization, Carbon dioxide excretion, LCA, Low carbon technology, long-lifetechnology

CO 2 排出量（t‐CO 2 /年）

CO2 Emissions (g-CO2/km)

concrete modifier

3. Assessment of CO2 reduction effect by low
carbon technology
It is possible to assess most of the technologies, except
the long-life technology, in Infrastructure LCA. Fig-2shows the results of estimate CO2 emissions and costs for
27 low-carbon technologies.
100XU

CO2 排出削減率（%）

2. Consideration of assessment method of long-life
technology
Long-life technology emits a large quantity of CO2 during
construction and reinforcing / repairing. But CO2 emissionsof entire in-service period are small. For instance, if theperiod is set by durable years of structure, long-life effect isassessed. On the other hand, if it is actually taken down
before the durable year, it is possible to be overrated. If theperiod is set short, considering uncertainty of future, thelong-life effect will not be assessed.
Fig-1 shows a calculation result for concrete modifierthat is expected to prevent cracks by applying to concrete
structures. This technology is expected to decay 20% of
the rate of deterioration of bridge, and to extend thedurable yeas from 50 years to 60 years. If the period is set
by durable year, the long-life technology is advantageous.
25
But if the bridge is
従来技術 Technology
Conventional
20
replaced at 40 years andLong-lifetechnology
長寿命化技術1520 years before the10durable years, the result
5is changed.
0After this, we plan toDurable
years 4040年
years 2020年
years
耐用年数
set installation strategy ofFig-1 The calculation result,the period by condition, to be able to assess the long-life
technology, and to improve general versatility ofInfrastructure LCA.

CO2 Emissions
reduction rate (%)

1. Introduction
By “Infrastructure LCA”, we came to be able tocalculate of CO2 emissions in the construction field
including infrastructure improvement. Low carbonizationof the construction field is needed for practical realizationof Infrastructure LCA. General versatility that can assess
various technologies is desired. But long-life technologies
can’t be evaluated by Infrastructure LCA.
In this study, NILIM examined how to evaluate
long-life technologies. Additionally we evaluated othertechnologies, and examined prospects for low-carbon
future by evaluation results.

80

AD60

AC40O
SI AA

②200-100①：Cost
コスト減、CO2大幅減
decrease, CO2 massive
reduction
cost・CO2 decrease②：Bothコスト・CO2ともに減slight decrease, CO2減
decrease③：Cost
コスト微増、CO
2
Cost increase, CO2 decrease④： コスト増、CO2減①CW-80PY ③H-60-40-20020The rate of increase工事コスト増加率（%）
in construction cost

Z④406080100Fig-2 The relationship between the rate of CO2 emission
reduction and cost increase / decrease

According to Fig-2, most of low-carbon technologies
belong to ②. Therefore, we concluded that the developmentof the technology which reduces both CO2 emissions andcosts has proceeded.
Also, by assuming the number of the adoption of 27technologies, and by multiplying CO2 reduction to thenumber of the adoption, CO2 reduction effect of using
low-carbon technologies was assumed about 400,000 t-CO2.
4. Conclusion
In order to achieve low-carbon society, it is effective toadopt the Infrastructure LCA into the social system.
“Index Integration Committee” and “LCI Calculation
WG” gave support to this study, and we wish toacknowledge valuable discussions with them.
http://www.nilim.go.jp/lab/bcg/siryou/kpr/prn0036.htm