The Estimation of the Functional Unit on Energy Consumption
and CO2 Emission concerned with Construction of Building
Lee, KangHee1,a, Choi, YoungOh2,b, Chae, Chang-U3,c, Kim, DaeHee4,d
1
Associate Professor, Andong National University, Republic of Korea
Doctoral graduate course, Kyungbuk National Univ., Republic of Korea
3
Senior Researcher, Korea Institute of Construction Technology, Republic of Korea
4
Researcher, Korea Institute of Construction Technology, Republic of Korea
a
[email protected], [email protected], [email protected], [email protected]
2
SUMMARY
A few methodologies have been recently developed to estimate the environmental affects when
various materials and components are used in building life cycle. The direct survey method has
limitations to analyze the environmental impacts due to the limitation of survey scope and cost.
Therefore, another indirect method has been developed as an alternative. The indirect method is
represented as the input-output analysis.
This paper aimed at analyzing the estimation of the environmental impacts of building materials
and provided the functional unit to 1000won-value, utilizing the input-output analysis as an indirect
estimation method. The results suggested that the main building material such as steel bar, cement and
ready mixed concrete are overally responsible for the energy consumption and CO2 emission. In other
words, most of the total consumption and CO2 emission are resulted at the work area using the main
building materials..
KEYWORDS : energy consumption, carbon dioxide emission, environmental impact, functional unit
1. INTRODUCTION
1.1 Research Background and Objectives
In 1997, the Kyoto Conference was held in Japan for the purpose of encouragement and observance of
the Convention on Climate Change worldwide. Under the world's trend of securing the environment,
Korea could not avoid the change of the environmental aspects any more. All of the world's
researchers have conducted various studies of investigations and actions for the environmental
conservation. Recently, the building industry also has come up with methodological research and
suggestions of low-impact building technologies to reduce the environmental burdens from the
building industry. At the point of building's physical lifecycle, the building has a life cycle with a
construction stage, a maintenance and a demolition stage, and it is demanded to study methods to
grasp energy consumption and environmental pollutants emission.
The Life Cycle Assessment(LCA) can be effectively utilized to get the amount of energy /
resource and elements of environmental impacts such as the Green House Gases, Acidifications in
building life cycle. LCA has a four steps with research goal and scope, inventory analysis, impact
assessment and improvement analysis. Expecially, an inventory analysis is the most important in Life
Cycle Assessment. The functional unit is inevitable to study the inventory analysis.
937
The purpose of this study is to provide a functional unit of various building materials to analyze
embodied energy and carbon dioxide emission which cause the Global Warming. The functional unit
is utilized to calculate the consumption amount of the energy and the emission amount of the carbon
dioxide.
1.2 Research Methods
LCA as research method of the environmental impact has been playing an important role in
the architectural field gradually. An LCA commonly could be classified four stages by
research goal & scope, inventory analysis, impact assessment and improvement assessment.
The method to find the functional unit could mainly be classified into a Survey Research, an
Indirect Estimating Method1 and a hybrid method. For analyzing each demand of building materials
and energy/resource for buildings, an Indirect Estimating Method is efficiently and effectively
used and utilizes the linkage among the building material industries. In other words, results of an
indirect estimating method is not better than the survey-based approach in accuracy, but the research
scope could be wider than the survey-based approach. An indirect estimation method is represented
with the input-output analysis. Therefore, this study used an indirect estimating method by the inputoutput analysis. In the Input-output analysis, the input-output table published by the Bank of Korea in
2000 was adapted for this study.
1.3 Research scope
This study provides the functional unit of various building materials using the input-output analysis.
The input-put table published by the Bank of Korea classifies industries into 404 sectors. Among these
sectors, it selected the sectors concerned with the building frame such as cement, section steel, steel
bar, cable and ready mixed concrete, etc. The number of sectors are 20 which are related to the
construction field.
Table1. Research sectors
No.
sector
39
sand and gravels
40
rubble
41
building stone
119
plywood
121
building lumber
123
wood products
182
domestic ceramic ware
184
building clays
185
cement
186
ready-mixed concrete
No.
187
188
190
197
198
201
215
220
221
222
sector
concrete products
limestone and gypsum products
asbestos and rock wool products
steel reinforcement and bar steel
section shape steel
steel pipe(except cast iron)
building metal products
screw products
wire products
hanging metal products
The functional unit is displayed with M ㎈/㎡ for energy and, ㎏-CO2/㎡ for the carbon
dioxide respectively. The analyzed sectors are shown in Table1.
1
KangHee Lee, ChangU Chae(2000), “An Estimation Method of the Life-Cycle Energy and CO2 of
Buildings”, The 3rd International Symposium on Architectural Interchanges in Asia, pp539～549.
938
Figure 1. The flow chart of input-output analysis
2. METHODOLOGIES
At the research of methodological phase, the input-output analysis could be begun through the
Leontief Table which contains the relationship between industries. It could be classified into six
stages[Figure 1] At first stage, the building materials required at the construction area shall be
investigated and classified by a classification system, which building material belongs to its industry
sector2.
Second, it would calculate the final demand required at the construction stage. This amount
would be summed by each industry sector and the construction part. Third, the amount of the material
and sector is distributed into the industry sectors according to the Input-Output table by the Bank of
Korea. According to input-output analysis, the final demand of building materials might be output
through the work types. Namely, it could be estimated by Inverse Matrix through 404 industry
linkages indicated Leontief table and could be estimated input of industry linkages according to the
final demand to use Formula 1. As multiplied Inverse Matrix by the final demand of building materials
at work type, input sectors of industry linkage could be estimated that is for this subject.
..............................................................( formula 1 )
X : Input of each industry linkage
(I-A)-1 : Inverse matrix of input coefficient matrix(aij) (I: unit matrix)
Y : The final demand of building materials in each works types
Fourth, the embodied energy consumption can be calculated with the amount of the industry
sector multiplied by the energy consumption unit at each oil, as shown in table 2. It could be estimated
to energy consumption and energy consumption value for building materials inputted through
extraction of energy department in input of industry linkage. As used table 2, above-mentioned energy
consumption can be estimated by the quantity of energy of building materials and be estimated by the
heating value of energy.
Fifth, after the energy consumption amount of each sectors is calculated, the emission amount of
CO2 could be calculated by multiplying the each emission unit, utilizing the contents of table2. CO2
emission could be estimated by multiplying energy consumption and CO2 emission value per heating
value.
Finally, the summation of the each material and sectors is conducted and calculated in functional
unit under building area. As shown above, CO2 emission could be added up through appropriate work
types, and that might be the process of valuing CO2 emission(㎏-c/㎡).
2
Each work type should be used by construction bill of quantity
939
Table2. Unit price, heating value and carbon dioxide coefficient of Energy
Carbon Dioxide
Factor
Unit Pricer
Heating Value
Coefficient
crude oil
242.4won/㎏
10,00 ㎉/㎏
20.0 ㎏ C/GJ
gasoline
946.1won/ℓ
8,300 ㎉/ℓ
18.9 ㎏-C/GJ
naphtha
218.9won/ℓ
8,000 ㎉/ℓ
20.0 ㎏-C/GJ
kerosene
417.0won/ℓ
8,700 ㎉/ℓ
19.6 ㎏-C/GJ
Burning
Rate
0.990
0.990
0.990
9,200 ㎉/ℓ
9,900 ㎉/ℓ
20.2 ㎏-C/GJ
21.1 ㎏-C/GJ
483.2won/㎏
8,700 ㎉/ℓ
12,000 ㎉/㎏
19.5 ㎏-C/GJ
17.2 ㎏-C/GJ
0.990
0.990
0.990
0.990
city gas
588.8won/N ㎥
11,000 ㎉/N ㎥
15.3 ㎏-C/GJ
0.995
natural gas
anthracite coal
340.3won/㎏
55.1won/㎏
13,000 ㎉/㎏
4,500 ㎉/㎏
17.2 ㎏-C/GJ
26.8 ㎏-C/GJ
0.980
6,600 ㎉/㎏
6,500 ㎉/㎏
25.8 ㎏-C/GJ
29.5 ㎏-C/GJ
0.980
0.980
860 ㎉/kwh
22.69 ㎏-C/GJ
-
light oil
middle oil
jet oil
LPG
390.9won/ℓ
214.1won/ℓ
257.8won/ℓ
bituminous coal
38.4won/㎏
coal
50.7won/㎏
hydroelectric power
electric
75.26won/kwh
atomic power
power
thermal power
3. RESULTS OF ESTIMATION OF ENERGY CONSUMPTION AND CO2 EMISSION
Energy consumption value and CO2 emission of building materials estimated by the input-output
analysis as shown at table 3. The sand and gravels consumed energy by 3.7418 MJ to produce amount
equal to 1000won-value and 20.8041MJ for a cement. Steel bar, section shape steel and gypsum
product are higher than any other building materials in energy consumption and CO2 emission. It is
interesting that the difference between the ready mixed concrete and cement are quite higher while
cement and remicon are main building materials in the reinforced concrete element. The difference at
energy consumption is about 6MJ/1000won and remicon is lower than cement.
940
Table3. Energy consumption value and CO2 emission value of building materials
CO2 Emission
energy
energy
code Industry
code
Industry
consumption
consumption
(㎏(MJ/1000won) CO2/1000won)
(MJ/1000won)
sand and
3.7418
0.1843 0187 concrete products
0039
16.1220
gravels
limestone and gypsum
26.6991
0040
rubble
13.7109
1.0098 0188
products
asbestos and rock wool
0041 building stone
23.5441
1.7317 0190
18.1618
products
steel reinforcement and
0119 plywood
5.5128
0.4227 0197
34.5489
bar steel
0121 building lumber
6.2516
0.4689 0198 section shape steel
30.7736
steel pipe(except cast
0123 wood products
7.3305
0.5442 0201
19.0529
iron)
domestic
0182
19.4190
1.4468 0215 building metal products
10.3042
ceramic ware
0184 building clays
26.8483
2.0164 0220
screw products
13.6138
0185
cement
20.8041
1.6404 0221
wire products
12.5666
ready-mixed
attaching metal
0186
14.4978
1.1141 0222
9.1935
concrete
products
CO2 Emission
(㎏CO2/1000won)
1.2726
2.0902
1.3979
3.3256
2.9207
1.7690
0.8748
1.1804
1.0575
0.7719
4. CONCLUSION
This study focused on the functional unit of building materials at the construction stage. It analyzed
the estimated energy consumption and CO2 emission as environmental load unit of building materials
based on the implementation of LCA to a building. Perfectly, provision of the functional unit leads us
to understand the LCA of a building. This study would be utilized as basic data that could be grasped
an environmental impact of Global Warming through estimation of unit of building materials.
For a quantitative grasping of energy consumption and CO2 emission at this stage, it is necessary
to graft onto standard analysis of material amount; It could be simplified against most of building
materials, and unit of building materials. It is necessary to have further research about estimation of
environmental impacts on the maintenance stage and the demolition stage in the future.
ACKNOWLEDGEMENTS
This work was supported by the ERC program of MOST(R11-2005-056-01005-00)
This research was supported by a grant(06ConstructionCore02) from Construction Core Technology
Program funded by Ministry of Construction & Transportation of Korean government
REFERENCES
Bank of Korea, 2002, 2000 Input Output Table.
Construction", Building and Environment Proceedings of the first International Conference, Session Material,
pp1~8.
J. N. Counaughton, 1987, "The Energy Cost of Construction", Building Economics, Session B, Design
Optimization, pp171~186.
941
Kanji Sakai et al., 1994, "Research on Environmental Load Estimation by Construction Activities in Japan and
Suitable Material Selection", Building and Environment Proceedings of the first International Conference,
Session Country, pp1~8.
Lee, K.H., Chae, C.U., 2000, An estimation method of life cycle energy and CO2 of a building, The
3rd International Symposium on Architectural Interchanges in Asia, AIK, JIK and ASC, pp. 539549. Selwyn N. Tucker and Graham T. Trelor, 1994, “Energy Embodied in Construction and
Refurbishment of Building", Building and Environment Proceedings of the first International Conference,
Session Material, pp1~8.
Tomonari Yashiro and Nobohiro Yamahata, 1994, "Energy-use and Carbon Dioxide Emission in Housing
942