Abstract. Technological Changes in Japanese Housing and Its Effects on Carbon Emissions

Transcription

1 Tehnologial Changes in Japanese Housing and Its Effets on Carbon Emissions Gloria P. GERILLA 1 Researh Fellow Department of Civil Engineering, Saga University 1 Honjo, Saga, , Japan Phone: Fax: a0440@.saga-u.a.jp Kardi Teknomo Leturer Institute of Lowland Tehnology, Saga University 1 Honjo, Saga, , Japan Phone: Fax: kardi@.saga-u.a.jp Kazunori Hokao Professor Department of Civil Engineering, Saga University 1 Honjo, Saga, , Japan Phone: Fax: hokao@.saga-u.a.jp Abstrat Population growth has led to the onversion of resoure-related land uses, suh as agriultural lands, to urban related land uses, like housing. Urban development has made life onvenient and omfortable. Travel has beome faster, ommuniation has beome easier. However, there are externalities that we need to fae due to urban development; Externalities suh as overrowding of ities whih leads to ontinual expansion of the ity (suburbanization); traffi ongestion; and the environmental quality is worsening. One aspet of urban development is the onstrution of residential and non-residential buildings in ities. This paper tries to study the hanges of arbon emissions indued by building onstrution. To be able to assess the future requirements of soiety in terms of infrastruture failities and its sustainability, a study on the historial hanges of arbon emissions and the relationship of material requirements to emissions are neessary. The fous is on the tehnologial evolution of Japanese building onstrution to be able to assess its environmental impats and to be able to reognize the material and energy requirements of building onstrution that ontribute to the total arbon emissions. The main ontribution of the paper is the environmental evaluation of the building onstrution system. Moreover, arbon emissions from building onstrution will be one of the results from the study. The Input-Output Approah oupled with Strutural Deomposition Analysis (SDA) is used to analyze the impats of Japanese building onstrution to the environment. The hanges in onstrution tehnology, emission struture are studied in this paper. It an be shown that these hanges ontribute to the flutuations in the arbon emissions from building onstrution during the 15 year study period. 1 Corresponding author

2 1 INTRODUCTION The reent enforement of the Kyoto Protool to mitigate the risk of limate hange has led governments, who are signatory to the Pat, to hold in hek their urrent emission levels and propose ways on how to limit their emissions. Infrastruture systems are neessary to the lives of human beings. However, the onstrution of infrastruture systems ontributes to the emissions to the environment. Buildings-related CO 2 emissions aount for one third of Japan s total CO 2 emissions (Ikaga, et al, 2002). Due to the immensity of CO 2 ontribution from residential and non-residential onstrution, it is neessary to study the reasons for this huge ontribution to CO 2 emissions. This paper tries to study the hanges of arbon emissions indued by residential and non-residential onstrution for a 15 year time period. In order to redue emissions from the onstrution setor, speifially the building onstrution setor, it is neessary to have a historial perspetive on how material requirements from building onstrution ontribute to ireased or dereased emission levels. The relationship between the assessment of environment loads and the eonomi system is modeled through the use of the Input-Output Methodology. The onventional Input-Output model has been employed to estimate environmental loads due to the prodution proesses of the entire eonomi system. Leontief (1970), Weir (1998), Gerilla, et al. (2000a) employed the stati input-output model to estimate environmental loads in relation to some aspet of the eonomy. These studies have not onsidered the hanging energy pries in the world, whih more or less affets the values of the estimated emissions. Bullard and Herendeen (1975), Piantanakulhai, et al. (1999), resolved the problem of hanging energy pries by the use of physial units for energy setors. The omparison of hanges in struture an be modeled through the strutural deomposition analysis (SDA). It represents a way of distinguishing major soures of hange in an eonomy. Several researhes had been made in this area using the SDA methodology like Rose & Chen (1991); Fujimagari (1989); Skolka (1989); Weir (1998) and others. Dietzenbaher and Los (1998), moreover, showed a detailed sensitivity analysis of the deomposition. Gerilla, et al. (2000b, 2001) studied the effets of historial and tehnologial hanges in the road onstrution industry whih made use of the retangular input-output method. The present paper shows a onnetion between the internal deomposition, wherein the diret and indiret dependeies in the eonomy are expliitly exhibited, and the external deomposition known as SDA is also done. The soures of hanges in arbon emission intensities indued by housing onstrution in Japan are studied from 1980 to A sensitivity analysis of hanges in the input oeffiients of the final demand onverter and that of the total arbon emission intensity is also presented. The paper is organized as follows: the following setion disusses the framework of the study. The deomposition of strutural hanges is done in Setion 2. Following that is the empirial appliation of the model using the IO tables of Japan. Coluding omments loses the paper in Setion 4. 2 FRAMEWORK OF THE STUDY The arbon emission model that is formulated in this paper iorporates the hierarhial relationship of the eonomi system. The methodology for modeling arbon emissions is shown in Figure 3.1. The basi input-output matrix is ombined with the primary energy setors to get a hybrid input-output matrix. The hybrid ommodity by ommodity diret requirements matrix is then alulated. Using the hierarhial deomposition tehnique, the

3 ommodity prodution fution is modeled. To hek the veraity of the modeled prodution fution, it is ompared with the hybrid prodution fution from the data. If the two prodution futions are equal then the next step is the estimation of the final demand for every building onstrution ategory alled the final demand onverter. The arbon intensity model is formulated after all the above proesses are done. A more detailed explanation of the proess is presented in the following setions. Energy Usage by Setors,E B asi I-O M atrix, Z Hybrid I-O M atrix, Z h Hybrid C om m odity by C om m odity Diret R equirem ents M atrix (A h ) Hierarhial Deom position M odeling, X = (I - A ) -1 Y NO X model = X hybrid YES C alulation of the Final Dem and C onverter for B uilding C onstrution Em ission Intensity M odel Form ulation CO es = Eg (I-A ) -1 f Figure 1. Flowhart of the arbon emission modeling 2.1 Hierarhial Deomposition The eonomy in this model is subdivided into 3 subsystems namely: the primary energy setors (es), the non-onstrution setor () and the onstrution setor, (s). The different interations and hierarhy between these subsystems are presented in this setion. The omparison of the emission struture among the primary energy setor, non-onstrution

4 setor and onstrution setor an be explained using the deomposition of the matries. The subdivision of blok matries A h are shown in the figures below. es s es A11 A12 A13 es A11 A12 A13 es O O O es O O O A A A A O O O A A O O O = s A A A s A O O s O A O s O O A Ah Aes A As (1) where: A 11 = input oeffiient sub-matrix of primary energy setors required by the output of primary energy setors (ton-c/ton-c); A 12 = input oeffiient sub-matrix of primary energy setors required by the output of noonstrution setors (ton-c/my); A 13 = input oeffiient sub-matrix of primary energy setors required by the output of onstrution setors (ton-c/my); A 21 = input oeffiient sub-matrix of non-onstrution setors required by the output of primary energy setors (MY/ton-C); A 22 = input oeffiient sub-matrix of non-onstrution setors required by the output of noonstrution setors (MY/MY); A 23 = input oeffiient sub-matrix of non-onstrution setors required by the output of onstrution setors (MY/MY); A 31 = input oeffiient sub-matrix of onstrution setors required by the output of primary energy setors (MY/ton-C); A 32 = input oeffiient sub-matrix of onstrution setors required by the output of noonstrution setors (MY/MY); A 33 = input oeffiient sub-matrix of onstrution setors required by the output of onstrution setors (MY/MY); The subdivision of the matries is also done to be able show the hierarhy of forward linkages, bakward linkages versus the isolated sub-system whih in this ase is the onstrution industry. The prodution fution for the setors was deomposed aording to the struture of the A h matries in (1). This deomposition shows the strengths of the linkages between the non-onstrution setor,, the onstrution setor, s and the primary energy, es, whih indues the amount of emissions from the onstrution setor. It also aids in the understanding of the relationships in the large eonomi system. The deomposed prodution fution is shown: X 1 = ( I + L A )( I + L A )( I A f (2) o es 1 s ) where: Lo = (I-A) -1 L 1 = (I-A a ) -1 A a = A + A s From equation (2), we have E g as the matrix of total arbon emission oeffiient indued by the non-onstrution setor for the prodution of final demand. This represents the emission struture of primary energy setors. It represents the interonnetions of the primary energy setor, the non-onstrution setor and the onstrution setor, whih ontributes to arbon emissions.

5 ( I + L A )( I + L A ) E g o es 1 = (3) s Equation (3) an be presented in matrix form as follow: Eg11 Eg12 Eg13 E = g Eg21 Eg22 Eg23 (4) Eg31 Eg32 Eg33 where: E g11 = primary energy output sub matrix of primary energy setors indued by the final demand of the arbon-produing setor; E g12 = primary energy output sub matrix of primary energy setors indued by the final demand of the non-onstrution setor; E g13 = primary energy industry output sub matrix of primary energy setors indued by the final demand of the onstrution setor; E g21 = non-onstrution output sub matrix of primary energy setors indued by the final demand of the arbon-produing setor; E g22 = non-onstrution output sub matrix of primary energy setors indued by the final demand of the non-onstrution setor; E g23 = non-onstrution output sub matrix of primary energy setors indued by the final demand of the onstrution setor; E g31 = onstrution output sub matrix of primary energy setors indued by the final demand of the arbon-produing setor; E g32 = onstrution output sub matrix of primary energy setors indued by the final demand of the non-onstrution setor; E g33 = onstrution output sub matrix of primary energy setors indued by the final demand of the onstrution setor; The arbon emission oeffiient vetor of primary energy setors is given in the matrix below: E = E E E (5) ge [ g11 g12 g13 ] E ge is defined as the diret and indiret emission output aquired as a result of the prodution proesses of the primary energy setors, non-onstrution and the onstrution setors. To be able to get the diret and indiret emission output disharged in the proesses of the noonstrution industry, we an deompose equation (5) to equation (6) as shown below: [ O Eg O ] E 12 g = (6) 2.2 Final Demand The building onstrution ommodity used as final demand in this paper is omposed of all buildings related onstrution suh as wooden building onstrution, steel onstrution, reinfored orete onstrution, et. The final demand used for the prodution of a building onstrution ommodity is a final demand onverter. A final demand onverter is used beause no detailed onstrution ategory is given in the basi I-O table. This onverter is

6 taken from the input transations of the onstrution setor. The final demand onverter, f i, is defined as the input oeffiient for onstrution as shown in equation 7. p f = i i (7) P where: p i = input oeffiient from the industrial setor i for the building onstrution ategory ; P i = ost of inputs from the industrial setor i for the onstrution ategory i The final demand for a building onstrution ommodity an be onverted into the hybrid system as given in the vetor: f [ es s ] t i = f f f (8) where: f i = final demand onverter for every onstrution ommodity ; f es = Final demand of the primary energy industry requirements of a onstrution ommodity; f = Final demand of the non-onstrution industry requirements of a onstrution ommodity; f s = Final demand of the onstrution industry requirements of a onstrution ommodity; Note that the symbol ( t ) means the transpose of the vetor. The final demand onverter used is the non-onstrution-input requirements of a building onstrution ommodity. The final demand onverter an also be subdivided into eah building onstrution ategory. The equation below shows the final demand onverter used for every onstrution ategory. f i sr r s w = f + f + f + f... (9) + The arbon emission fution an be formulated from equations (6), (10) and (13); the total arbon emission intensity from the primary energy setors indued by the non-onstrution setor for the prodution of a onstrution ommodity is given by: where: CO es = E g 1 ( I A ) f (10) CO es = Total arbon emission intensity of a onstrution ommodity indued by the proesses in the non-onstrution setor for the prodution of a onstrution ommodity (ton-c/my); E g = Carbon emission oeffiient vetor of primary energy setor; (I - A ) -1 = Total requirements matrix indued by the non-onstrution setor; f = Final demand of the non-onstrution requirements of a onstrution ommodity; 2.3 Strutural Deomposition Analyses The soures of hanges in arbon emission intensity are studied using SDA. The total hange in arbon emissions intensities is deomposed into effets aused by the hanges in the emission struture of primary energy setors, E g, hanges in non-onstrution tehnology,

7 (I A ) -1 as well as hanges in the onstrution tehnology of the building onstrution. Using equation (10), we an arry out its deomposition over time by es { E ( I A ) f } E ( I A ) g 1 { g f } CO = (11) The subsripts 1 and 0 denote the future year t1 and base year t0, respetively. If we let L = (I A ) -1, we have: CO = E L f E L f (12) es g1 1 1 g0 0 0 Equation (12) an be transformed into six different types of deomposition forms, whih are shown in equation (13). CO = E L f + E L f + E L f es g 1 1 g0 1 g0 0 = E gl0f 0 + Eg1 L f 0 + Eg1L 1 f = E gl1f 0 + Eg0 Lf 0 + Eg1L 1 f E gl0f 0 + Eg1 L f 1 + Eg1L 0 f = (13) = E gl0f 1 + Eg1 L f 1 + Eg0L0 f = E gl1f 1 + Eg0 Lf 0 + Eg0L1 f E g represents the hanges in the emission struture of the primary energy setor, while L represents the hanges in the non-onstrution tehnology and denotes the final demand hanges of the non-onstrution requirements of a building onstrution ommodity. Dietzenbaher and Los (1998) suggested that the average of polar deompositions be omputed for ases with more than two determinants. So the average effets of the determinants are omputed. The average effets of the emission struture hanges of the primary energy setors, E g an be alulated by the formula: f ( 6) [ 2 ( E L f ) + 2 ( E L f ) + E L f + E L f )] 1 g 1 1 g 0 0 g 1 0 g 0 1 (14) The average effets of the hanges in non-onstrution tehnology are manifested in equation (15). ( 1 6) [ 2 ( E L f ) + 2 ( E L f ) + E L f + E L f ] g0 0 g1 1 g0 1 (15) Equation (16) estimates the average effets of hanges in onstrution tehnology. g1 0 { 2( E ) ( ) g0l0 f + 2 Eg1L 1 f + Eg1L 0 f + Eg0L1 f } ( 1/6) (16) It should be noted that the final demand used in the study is a final demand onverter, whih onsists of the input oeffiients of eah building onstrution ategory, in effet, f an be alled the hanges in the onstrution tehnology for eah building onstrution ategory.

8 3 RESULTS The result of the alulations and analysis is presented in this setion. The deomposition equations presented in setion 3.3 are applied to the analysis of the hanges in the arbon emission intensities for building onstrution from 1980 to These periods were hosen to be able to trae the historial hanges of arbon emissions in Japan indued by housing and non-housing onstrution. The appliation of the deomposition equations are done for the residential and non-residential building onstrution and its ommodities. 3.1 Basi Data The data used in the study were the basi ommodity by ommodity input-output tables from the Management and Coordination Agey; the energy usage by setors based on the inputoutput analysis and the input tables for onstrution work from the Ministry of Constrution, Japan. All the above mentioned data were olleted for the years 1980, 1985, 1990 and The setor lassifiation in the input-output tables for different years do not orrespond to eah other therefore all the tables were aggregated into a 60 x 60 matrix for eah analysis year. The aggregation was done to be able to make all the setors uniform and manageable. Moreover, all monetary terms were onverted to 1985 pries to failitate omparison and to exlude prie omponents from the analysis of strutural hange. The setors were rearranged aording to the primary energy setors, non-onstrution setor and the onstrution setor. There are 7 setors in the primary energy setor (es) whih is omposed of oal mining, rude petroleum and natural gas, Limestone, petroleum refinery produts, oal produts, eletriity and power generation and gas supply and steam. Two setors are from the onstrution industry (s) namely: the residential and non-residential onstrution setor and ivil engineering onstrution setor, and lastly, the other 51 setors are the non-onstrution () setors. The building onstrution ategory was divided into residential onstrution and nonresidential onstrution. Further subdivision of these two ategories was made into wooden and non-wooden onstrution. Non-wooden onstrution was again divided into steel onstrution, steel reinfored orete onstrution, et. 3.2 Carbon Emission Survey Figure 2 shows the arbon emission intensity for residential and non residential onstrution for the 15 year study period. These intensities are based on 1985 onstant pries. The trend of arbon emissions an also be seen from 1980 to During the 15 year period, the arbon emission intensity ireased by about 65% for residential housing onstrution, while there was only a 26% irease in emissions for non-residential onstrution during the same period. The emission level was at its lowest from 1985 to 1990, for both residential and nonresidential housing onstrution. There was a 27% and a 26% derease in emissions during this period for residential and non-residential onstrution, respetively. The derease in emission intensities from 1980 to 1985 was not so drasti for residential onstrution (only 6%) ompared to the 22% derease for non-residential onstrution. The trend in emissions is similar for both residential and non-residential onstrution. It is noted, however, that emissions from non-residential building onstrution are larger than those of residential

9 onstrution. The lowest emission intensity for the 15 year period was in 1990 with a 620 kg- C/MY intensity for residential onstrution while a 687 kg-c/my intensity for nonresidential onstrution. The emission redution by the Kyoto Protool relative to 1990 levels is proper beause of the lowest emission intensity during the period. However, it will be diffiult to abide by the guideline beause the arbon emission intensity ireased in 1995 with an irease of as muh as 145% for residential onstrution and about 123% for nonresidential onstrution 3500 Carbon Emission Intensity (kg-c/my) Year Total Residential Constrution Total Non-Residential Constrution Figure 2 Carbon Emission Intensities for Residential and Non-residential Constrution for a 15 year period Figure 3 shows the arbon emission intensities aording to the ontribution of primary energy. It an be seen that Petroleum Refinery Produts dominate the other primary energy setors in the ontribution to arbon emissions. This dominae is refleted for both residential and non-residential onstrution. Usage of petroleum refinery produts was about 35% ompared to other primary energy setors in Even though there was dominae in this setor, we an see that the usage of petroleum refinery produts gradually dereased from 23% in to 36% from The gradual redution in arbon emission intensity from this setor was, however, nullified beause of an irease of arbon emission intensity by 200% during The seond largest emitter of arbon emissions is the usage of oal produts in the onstrution proess. On average, the ontribution of the usage of oal produts for residential and non-residential onstrution to arbon emissions was about 29%. For the 15 year period, oal mining and gas supply setors ontributed to the largest irease in arbon emission. From the arbon emission struture of residential and non residential onstrution, we move into the non-onstrution setors, whih ontributed to the flutuation of emission intensities during the 15 year period. Figure 4 shows the material/servies ontribution to the building onstrution emission intensity. The seleted non-onstrution industries are ement, pig iron and rude steel, transportation, and steels. The seletion was done based on the ranking of the emission intensities indued by the non-onstrution industry. The graph shows that for eah analysis period, pig iron/rude steel ontributed to the largest amount of arbon emissions.

10 Carbon Emission Intensity (kg-c/my) Non- Residential Residential Non- Residential Residential Non- Residential Residential Non- Residential Residential Type-Year Coal Mining Limestone Coal Produts Gas Supply and steam Crude Petroleum & Natural Gas Petroleum Refinery Produts Eletriity and self-power generation Figure 3 Carbon emission intensities aording to the ontribution of primary energy Carbon Emission Intensity (kg-c/my) Year Pig iron and rude steel Cement and ement produts Transportation, paking and its servies Steels and steel produts Figure 4. Material/servies ontribution to the building onstrution emission intensity

11 The seond highest material ontributor to arbon emission intensity is the ement industry. For the 15 year period, we see that emissions from ement and ement produts signifiantly dereased by about 36% while emission intensities for transportation servies ireased by about 77%. The greatest ontributor to the irease in emission intensity for the 15 year period is steels and steel produts with a 103% irease. The reasons for the hanges in arbon emissions are disussed in the next setion. 3.3 Results from the Deomposition Analysis The results of the deomposition analysis of the strutural hanges in arbon emission intensities indued by building onstrution are presented in this setion. Table 1 and Table 2 present the results of the deomposition equations used in the setion 2. Table 1 shows the deomposition analysis for residential onstrution while Table 2 shows the results of the deomposition analysis from non-residential onstrution. The results from the deomposition for both residential and non-residential onstrution show the same trend. Table 1 Deomposition Analysis for Residential Constrution (kg-c/my) Period Eg A f CO es Table 2 Deomposition Analysis for Non-Residential Constrution (kg-c/my) Period Eg A f CO es The total hanges in arbon emissions ( CO es ) for a ertain time interval an be deomposed into hanges in emission struture, Eg, hanges in non-onstrution tehnology, A, and hanges in the input oeffiients of building onstrution, f. Emission struture hanges are sets of reiproal ation of the subsystems that indue arbon emissions. Changes in input oeffiients are basially hanges in the building onstrution tehnology. The irease in arbon emissions from is a result of the irease in the input oeffiients of the building onstrution; this is true for both residential and non residential onstrution. Another reason for the irease is the irease in the emission struture; this might mean an irease in the building onstrution industry s usage in arbon intensive primary energy soures. It is important to note that a negative effet in arbon emission intensity resulted from the hanges in non-onstrution tehnology. This negative effet is explained as improvement in the overall non-onstrution tehnology used for onstrution during this period.

12 The period in indiates that the derease in emission is mainly due to the hange in the primary energy setors emission struture. This reveals that dependee on energy intensive industries has waned and shifted to less energy intensive industries, whih ontributed to the derease in arbon emissions. Another reason is the improvement of noonstrution tehnology during this period. The biggest dip in the emission hange ourred during ; this is the result of improvement in emission struture, non-onstrution tehnology and onstrution tehnology. This reflets ireased industrial effiiey and produtivity in onstrution design and methods. The slowing down of the eonomy due to the bursting of the bubble eonomy during this time maybe another reason for the hange in the input oeffiients of building onstrution. For , a drasti irease in arbon emission intensity ourred as ompared to the previous period. This is due to the irease in final demand as well as ireased hange in the emission struture although the non-onstrution tehnology improved in this period it was offset by irease in other variables. We saw that the biggest derease in arbon emission intensity ourred during We will look into the material inputs to residential onstrution whih ontributed to the derease in intensities. Table 3 shows the top 5 intermediate input requirement of building onstrution whih ontributed to the major derease in arbon intensity for The top 5 material inputs to residential onstrution that ontributed to the derease in arbon emissions for are: metal produts for onstrution, ement and ement produts, steels, timber and wooden produts and organi and inorgani hemials. The table shows that metal produt for onstrution ontributed to a marked derease in arbon emission intensity for the period. The arbon emission intensity embedded in the metal produts roughly omposes about 45% of the total hange in arbon emission intensity. This is due to the improvement in the emission struture, non-onstrution tehnology and onstrution tehnology. For steels, however, we see an improvement in the emission struture and manufaturing tehnology but there was an irease in the input oeffiient for onstrution whih is an irease in the final demand for steel. Table 3 Effets that ontributed to a major derease in arbon intensity from residential onstrution for (kg-c/my) Period Industry E g A f Total Metal produts for onstrution Cement and ement produts Steels and steel produts Timber and wooden produts Organi and inorgani hemials

13 Table 4 shows the effets whih ontributed to the major irease in arbon emission intensity from It an be seen that timber and timber produts, metal produts for onstrution, furniture and fixtures, ement and transportation were the top 5 material/servie inputs whih led to the irease in arbon emission. We an see that for the 5 material inputs, their manufaturing tehnology improved as seen in the negative effets while both emission struture and onstrution oeffiient inputs had positive effets. Table 4 Effets that ontributed to a major irease in arbon intensity from residential onstrution for (kg-c/my) Period Industry E g A f Total Timber and wooden produts Metal produts for onstrution Furniture and fixtures Cement and ement produts Transportation, paking and its servies Results from the Sensitivity Analysis A sensitivity analysis of the arbon emission intensity based on the input oeffiient of building onstrution was done to be able to know how muh hange in arbon emissions will our for a hange in the onstrution input oeffiients. The onstrution input oeffiients hosen are material inputs whih ontributed in the major irease in arbon emissions for as seen in Table 4. Figure 5 shows the result of the sensitivity analysis. The absissa shows the onstrution input oeffiient while the ordinate shows the arbon emission intensity. The values for the x-axis show a derease or irease from the urrent input oeffiient (1). A value of 1.1 in x shows a 10 perent irease in the input oeffiient of a ertain material input. The sensitivity was done suh that when an input f i is altered, the other input oeffiients are also hanged aording to the sale of its ontribution to the sum of the input oeffiients. As seen in Figure 5, arbon emission intensity embedded in timber and its produts is highly sensitive to small hanges in the input oeffiient of timber and its produts. We see that if we redue the input oeffiient of timber by 50% the hange in the total arbon emission intensity will be redued by about 2.5%. Similarly, arbon emission from ement and ement produts are also sensitive. An irease in the input oeffiient of ement and ement produts by 50% will generate an irease in arbon emission intensity by 1.6%. The arbon emission intensity of the other material/servies input like metal produts for onstrution and transportation are not so sensitive to the hanges in its input oeffiient.

14 Carbon Emissions (ton-c/my) Final Demand Timber and wooden produts Cement and ement produts Transportation, paking and its servies Furniture and fixtures Metal produts for onstrution Figure 5. Sensitivity analysis done between the input oeffiients of residential onstrution and arbon emission intensity Knowing the sensitivity of the arbon emissions to hanges in the material/servies input oeffiients is important in determining whih setor should be foused on when trying to redue the arbon emissions from building onstrution. Design of buildings using different types of materials whih are not so arbon intensive/sensitive an be another way of trimming down arbon emissions. 4 CONCLUDING REMARKS The strutural deomposition analysis (SDA) developed using the hybrid framework has shown the important soures of hange in arbon emissions indued by building onstrution. The hanges in emission struture, non-onstrution input struture, and building onstrution tehnology has been learly defined in the model. Another feature of the study is the differentiation between residential and non-residential building onstrution, whih affet the arbon emission intensities. The 15 year analysis period shows that arbon emission intensity signifiantly ireased for both residential and non-residential onstrution. The reasons for the irease were the irease in the input oeffiients of the building onstrution; this is true for both residential and non residential onstrution. Another reason for the irease is the irease in the emission struture; this means an irease in the building onstrution industry s usage in arbon intensive primary energy soures, mainly petroleum refinery produts. It is worthy to note that during the 15 year period, material and manufaturing tehnology for building onstrution improved extensively. The greatest improvement in residential and nonresidential onstrution tehnology an be seen in the period of where the greatest

15 derease in emissions an be seen. This improvement led to a derease in emission levels. This reflets ireased industrial effiiey and produtivity in onstrution design and methods. The slowing down of the eonomy due to the bursting of the bubble eonomy during this time maybe another reason for the hange in the input oeffiients of housing and non-housing onstrution. The shifts in usage of primary energy also led to a derease in arbon emission levels. It an be seen that timber and timber produts, metal produts for onstrution, furniture and fixtures, ement and transportation were the top 5 material/servie inputs to housing onstrution whih led to the irease in arbon emission. We an see that for the 5 material inputs, their manufaturing tehnology improved as seen in the negative effets while both emission struture and onstrution oeffiient inputs had positive effets. The minute and large hanges in the usage of some materials, like timber and it produts and ement and its produts, lead to a drasti hange in arbon emissions ompared to other material/servies inputs. Knowing the sensitivity of the arbon emissions to hanges in the material/servies input oeffiients is important in determining whih setor should be foused on when trying to redue the arbon emissions from housing onstrution. Design of houses using different types of materials whih are not so arbon intensive/sensitive an be another way of trimming down arbon emissions from this setor. 5 REFERENCES Bullard, C. and R. A. Herendeen, 1975, The energy ost of goods and servies, Energy Poliy, Dietzenbaher, E. and B. Los, 1998, Strutural Deomposition Tehniques: Sense and Sensitivity, Eonomi Systems Researh, Vol. 10, No. 4, pp Fujimagari, D., The Soures of Change in Canadian Industry Output, Eonomi Systems Researh 1 (2), Gerilla, G., H. Inamura and Y. Takeyama., 2000a, Environmental Impats of the Building and Road Constrution Industry in Japan, Proeedings of the International Symposium on Lowland Tehnology, 4-6 Otober 2000, Saga, Japan. Gerilla, G., S. Kagawa and H. Inamura, 2000b, Environmental Effets due to Changes in Constrution Tehnology, 11 th Pan Paifi Assoiation of Input-Output Studies Conferee, Sendai, Japan, November 3, Gerilla, G., S. Kagawa and H. Inamura, 2001, A Study on Environmental Effets Due to Historial Changes in Tehnology, Seleted Proeedings of the 9 th World Conferee on Transport Researh. Ikaga, T., S. Murakami, S. Kato and Y. Shiraishi, 2002, Foreast of CO 2 Emissions from Constrution and Operation of Buildings in Japan Up to 2050, Journal of Asian Arhiteture and Building Engineering, November 2002, Vol. 1, No. 2, pp Leontief, W., Environmental reperussions and the eonomi struture: An inputoutput approah, The Review of Eonomis and Statistis 52, 3.

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