Building Energy Consumption and CO 2 Emissions in China

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1 Buldng Energy Consumpton and CO 2 Emssons n Chna ZHOU WEI, MI HONG 2,2 Supervser of Admnstraton School Zhejang Unversty CHINA ttomcc@gmal.com 2 spsswork@63.com(correspondng author) Abstract: - Based on the theory of Lfe-Cycle Energy Analyss, the energy consumpton of macro-level buldngs n Chna was analyzed, and the key factors n every Lfe-Cycle phase were ponted out. Wth the analyss of buldng lfe-cycle energy consumpton, carbon doxde emssons related to buldngs were calculated. It was ndcated that the energy consumptons of buldng materals producton and buldng operaton account for largest share n buldng energy consumpton. Reducng energy consumpton on buldng operaton and buldng materals were mportant to buldng energy savng and carbon doxde mtgaton. Key-Words: - ; Macro buldng; Lfe-Cycle analyss; CO 2 emssons; Energy savng Introducton Accordng to the report of the Unted Natons Envronment Programme (UNEP), energy use of buldng sector account for 30% to 40 % of global prmary energy consumpton[], and therefore contrbute to sgnfcant greenhouse gas (especally carbon doxde, CO 2 ) emssons. EC research has ndcated that by mprovng energy effcency, carbon emssons from buldngs could be reduced by 22% [2]. Now Chna s the country whch emts most carbon doxde n the world (IEA, 2009)[3], Chna has been consdered responsble for more than half of the global ncrease n carbon doxde emssons of 3.%[4]. Now Chna s undergong urbanzaton and on an unprecedented scale, about 200 mllons people wll move to ctes n Chna n the future years. They need more buldng and more nfrastructural facltes. Now energy use for space heatng, coolng, ventlaton, lghtng of buldng accounts for 30% of total energy consumpton n Chna. Urbanzaton rato of Chna ncreases from 7.92% n 978 to 45.68% n 2008, and grows 0.93 percent per year, and t wll keep a same speed n the next years. The lvng space of the average Chnese grow from 22.7 square meters n 2000 to 30.2square meters n In 2008, 760 mllons square meters buldng were bult n urban areas and 834 mllons square meters buldng were bult n rural areas. So energy consumpton of buldng wll grow n a large scale, the same s true of carbon doxde emssons. It s essental for the buldng constructon ndustry to mprove the energy effcency and reduce envronmental mpact (polluton, carbon doxde emssons, etc). An effectve assessment system s needed to estmate the mpact of buldng on envronment. For ths purpose, Lfe-Cycle Energy Analyss (LCEA) s appled n ths paper to calculate the energy consumpton. LCEA provde better understandng and better estmaton of energy aspects n the Lfe-Cycle of buldng. The Lfe-Cycle of a buldng can be dvded to several phases, these phases are producton of buldng materals, on-ste constructon, operaton, demolton and waste management[5]. Prevous lfe-cycle studes found that energy for operaton s accountng for the domnatng part (Cole, 996)[6]. Researches of low energy buldngs showed that the energy demanded for materal producton accounts for largest share of the total energy consumpton. (Nemeth Wnter, 998)[7]. Study on the potental energy savngs by recyclng the buldng materals ndcated that t may be more mportant to desgn a buldng for recyclng than to use materals whch requre lttle energy for producton (Catarna Thormark,2000)[8]. Research on Chna s energy use of buldngs ndcated that f manufacturng technques reman the same as current trend, Challenges to the goals for energy consumpton n Chna wll appear n the next decade [9]. More than 90% of conventonal buldngs n Chna are hgh-energy buldngs, and lttle of newly bult buldngs are low-energy buldngs. If buldngs contnue to be constructed accordng to current trends, the energy demanded and envronmental mpact of the pressure on urban areas wll be enormous. Ths paper focuses on energy consumpton of natonal ISBN:

2 buldngs wth LCEA, and estmates the buldngrelated carbon emssons. 2 Energy Consumpton of Buldngs Lfe-Cycle Buldng energy consumpton can be expressed by two perspectves: sngle buldng energy consumpton and macro-level buldng energy consumpton. There are varous buldngs (constructed for resdental, offce and commercal, publc buldngs, etc) n one country, and they consume energy n dfferent ways. It s mpossble to analyze energy consumpton of every buldng, but we can get result n average level. On ths bass, energy consumpton of buldngs n the whole country (macro-level) can be estmated. certan stage. Theoretcally t can be calculated by summary energy consumpton of all buldngs, but t s mpossble to get all energy data of buldngs. Macro-analyss s suted for gettng the energy data of dfferent phases of MECB. The mathematcal equatons for macro energy consumpton of buldngs s smlar wth equatons (),just dfferent detals n lfe-cycle phases only. 2. Buldng Materal Producton In order to calculate energy consumpton of buldng materal producton, t s necessary to fnd the shares of the energy consumpton of a certan materal or a process (for nstance, transportaton) related wth buldngs to total energy consumpton of a certan materal or a process of natonal economy. Energy data can be obtaned accordng related lteratures and the data of Chna statstcal yearbook[9]. Table Share of materal n buldng constructon Share of materal n Buldng Materal buldng constructon Steel product 4% Nonmetallc materal 98% Nonferrous metal 25% Chemcal materal 25% Data resource: L Zhaojan, Jang Y. Analyss on generally energy consumpton of buldngs n Chna[J], Transactons on Buldng, 2006,53(7): Fg. Phases of Lfe-Cycle energy analyss For sngle buldng, LCEA s an approach that accounts for all energy consumpton of a buldng n dfferent phase: buldng materal producton; constructon phase; operaton phase; demolton and waste management (as shown n Fg.). Energy consumpton of sngle buldng n ts Lfe-Cycle can be expressed as (n term of prmary energy): E = E + E + E + E () T mp bc op where E T s the total energy consumpton of a sngle buldng; E mp s energy consumpton n buldng materal producton; E bc s energy consumpton n buldng constructon; E op s energy consumpton n operaton phase; E de s energy consumpton n buldng demolton. Macro energy consumpton of buldngs (MECB) s energy consumpton of all buldngs n an area n a de Sx knds of materals mostly used n buldng, they are cement, rebar and structure steel, plate glass, alloy alumnum, wood and PVC ppes[0]. When the buldng s demolshed, parts of buldng materals can be reclamed. The reclamable rates of varous types of materals are dfferent. By nvestgaton, the reclamable rates of several buldng materals are defned respectvely as 90% (metal), 50% (brck), 20% (wood), and 0% (cement). The rate of all other materals s defned as 0%[]. So energy use of buldng materal producton can be calculated as followng: E n mp = = C [ X ( α ) + αx ] r (2) Where X s energy consumpton of manufacturng materal () all over the country; C s share of materal () n buldngs averagely; α s reclam coeffcent of materal (), X r s energy consumpton n reclamng materal (). 2.2 Buldng Constructon and Demolton The buldngs constructon phase, ranges from extractng raw materals to the buldng works on ste. ISBN:

3 Energy s requred to make varous machnes work. At the end of buldngs servce lfe, energy s demanded to demolsh the buldng and transportng the waste materal to landfll stes and/or recyclng plants. Ths energy s termed as demolton energy[2]. Constructon ndustry s regard as an ndustry ncludng buldng constructon and demolton, so statstc data of buldng constructon and demolton are ncluded n Chna statstcal yearbook. of buldng constructon and demolton accounts for.4% to.7% n total energy consumpton n recent years[3]. One of the reason s that buldngs constructon and demolton only last for a shot tme n lfespan. 2.3 Operaton Energy Energy s used for space heatng, coolng, ventlaton, and lght buldngs, hot water supply and other electrcal applances. n ths phase usually accounts for the largest share n total energy demand. Consderng dfferent clmate condton, operaton energy of buldng vary from north to south n Chna. In the north, energy consumpton of space heatng s the domnatng part n wnter; whle n the south energy consumpton of coolng s the domnatng part n more than four months. Lghtng demands not much energy n prvate buldng, but t s opposte n publc buldng. The hot water supply and household electrcty use depend to a large extent on the users. Operaton energy can be expressed as followng: m E op = L = (3) Where E op s energy consumpton n operaton phase; L s energy consumpton of servce (). 2.4 Indrect energy Except the energy consumpton n ts lfe-cycle phases, there s ndrectly energy consumpton n buldng lfespan. Indrectly energy s demanded by constructon equpment when they were manufactured, operated, transported; and by energy resource tself when they were explored, transferred, transported, etc. Indrectly energy can be expressed as: E n = m = ( Y E y ) where E n s ndrectly energy n the lfespan of the buldng; E y s total value of ndrectly energy (); Y s the share of ndrectly energy () n ndustry-related energy consumpton. Y can be found n table 2. Table 2 Share of ndrectly energy Buldng-related ndrectly ndustry ndustry-related Transportaton 30% Energy ndustry 45.5% Mechancal Manufactur 70% Data resource: L Zhaojan, Jang Y. Analyss on generally energy consumpton of buldngs n Chna[J], Transactons on Buldng, 2006,53(7): Carbon emssons of Buldngs On the bass of analyses above we can calculate the total energy consumpton of buldngs n Chna. In order to study the carbon emssons of buldngs, t s necessary to get the energy structure recently. Chna stll reles on fossl fuel heavly, especally coal. From 200 to 2008, Coal accounts for 66% -70% n Chna s energy consumpton, ol accounts for 20% or so. Clean energy such as nuclear power, hydropower and wnd power sum up to 7%-8%. Consumpton of fossl energy brngs great carbon emssons, as well as serous polluton. Table 3 Energy structure of Chna (%) coal ol natural gas Clean energy Data source: Chna statstcal yearbook, Suppose energy consumpton structure of buldng s the same as natonal energy structure, the consumpton of every knd of energy (coal, ol, natural gas, etc) can be calculated. And accordng to the data of table 4 and table 5, carbon emssons of every knd of energy can be calculated too. Table 4 CO 2 Emssons from the consumpton of fossl fuel Crude Natural Fuel Coal ol Gas Potental CO 2 emssons factor (g /0 6 KJ) Data sources: Workgroup 3 of the Natonal Coordnaton Commttee on Clmate Change. ISBN:

4 4 Concluson Table 5 energy consumpton and CO 2 Emssons of buldngs phase Producton Share n lfe cycle energy of consumpton of buldngs(%) materals On-ste Share n lfe cycle energy constructon consumpton of buldngs(%) operaton Share n lfe cycle energy consumpton of buldngs(%) demolton and Share n lfe cycle energy waste consumpton of buldngs(%) management Total energy consumpton of buldngs Carbon doxde emsson of buldng (Mt) From table 5 t can be found that energy consumpton of buldngs account for 4%-46% of total energy consumpton, and keep ncreasng. Energy demand n buldngs operaton accounts for the largest share, more than 50% of lfe-cycle energy consumpton of buldngs. The second share s the phase of buldngs materals producton, more than 30% of lfe-cycle energy consumpton of buldngs. Carbon doxde emssons of buldngs are remarkable, and reach 2853Mt n Most buldngs n Chna are hgh-energy buldng. (per unt area) of large-scale publc buldngs s about ten tmes as much as prvate buldngs. The survey and statstc analyss on publc buldng energy consumpton some ctes reveals that t s common that energy consumpton among smlar publc buldngs has a large gap up to two tmes[4]. Energy demand of publc buldngs operaton accounts for 30% of total energy consumpton. Energy waste n publc buldngs s more heavly than prvate buldngs. Lfespan of buldngs n Chna s years averagely, and s much shorter than that n developed countres. Terrble qualty of buldngs and lack of scentfc plannng shorten the lfespan of buldngs, and result n serous waste of energy and other natural resource. Further more, terrble qualty of buldngs may result n heavy casualtes and loss of property. In Wenchuan earthquake (May 2, 2008), more than 3.3 thousand schools were destroyed and more than 9 thousand students ded. So the short lfespan of buldngs ncrease the carbon emssons n Chna. 5 Further Dscusson Because of the huge number of populaton and unprecedented urbanzaton, Chna s newly bult buldngs were the most n the world n recent years m 2 new buldngs were bult n 2007, at the same tme, cement consumpton accounted for 55% of the world and steel consumpton accounted for 30% of the world. As a developng country wth low per capta ncome, Chna s government s n pursut of growth of gross domestc product GDP excessvely. Constructon s both a drver and a consequence of ncreasng GDP. Constructon ndustral typcally provdes 5% to 0% of employment at the natonal level and normally generates 5% to 5% of the ISBN:

5 GDP[5]. But n some areas, buldngs whch were bult not more than 5 years often be demolsh because hgher buldngs wll be bult on the same ste. In 2007, Chna s GDP account for 6% of the world, but steel and cement consumpton reached 30% and 55% of total consumpton n the world. So the buldngs and constructon sector has largest potental for energy savng and mtgatng carbon emssons responsble for envronment. It s essental for buldngs constructon to reduce energy consumpton for sustanable development. Energy savng of large-scale publc buldngs s the key pont of buldng energy savng. On the other hand, mprovng the buldngs qualty and lengthen the lfespan of buldng wll also reduce the energy consumpton and carbon doxde emssons. The choce of energy resource s also mportant. Chna needs to mprove energy effcency, and optmze the energy structure. If clean energy ncludng nuclear power, hydropower and wnd power account for hgher share of the total energy, carbon emssons wll be reduced notable. 6 Acknowledge The authors gratefully acknowledge the fnancal support from: Natonal Foundaton of Natural Scences of Chna Research on Urban-rural Labor Market Integraton and Implementaton Mechansm (NO ) 2Natonal Key Socal Scence Foundaton Project Performance Evaluaton, Polcy Smulaton and Capacty Buldng of Response to Major Publc Emergences (NO.08ASH006). 3 Zhejang Academy of Populaton Urbanzaton and transton of low-carbon economy n Zhejang (No.200-3). 4 Chnese Mnstry of Educaton Human Socal Scence major project Constructon of Capablty on Copng wth Threat of Non-Tradtonal Securty (No.08JZD002-D). References: []Unted Natons Envronment Programme. Buldngs and Clmate Change: Status, challenges and Opportuntes, [2]European Unon. Drectve on the energy performance of buldngs. UK: Department for Envronment, Food & Rural Affars. defra.gov.uk/envronment/energy/nternet/buldn g.htm, [3]IEA. CO 2 emssons from fuel combuston - hghlghts. hghlghts. pdf, [4]Yan, Y.F.,Yang,L, Chna s foregn trade and clmate change: a case study of CO 2 emssons. Energy Polcy, Vol.38, 200, pp [5]Ramesha, Rav Prakasha, K. Shuklab. Lfe cycle energy analyss of buldngs: An overvew. Energy and Buldngs, Vol.42, 200, pp [6] Cole, J. Lfe-cycle energy use n of the buldngs. Buldng and Envronment, Vol.3, 996, [7]Nemeth Wnter, B. Energy use n low-energy buldngs, IBT report, 998. [8] Catarna Thormark. Includng recyclng potental n energy use nto the lfe-cycle of buldngs. Buldng Research & Informaton, Vol.28, 2000, pp [9] Yuan Chang, Robert J. Res, Yaowu Wang. The emboded energy and envronmental emssons of constructon projects n Chna: An economc nput output LCA model. Energy Polcy, Vol , pp [0]L Zhaojan, Jang Y. Analyss on generally energy consumpton of buldngs n Chna, Transactons on Buldng,Vol.53,2006,pp []Gong Zhqang. A quanttatve method to the assessment of the lfe cycle emboded envronmental profle of buldng materals. Department of Constructon Management, School of Cvl Engneerng, Tsnghua Unversty, Bejng, [2]Zhang Zhhu, Xng Wu, Yang Xaomn, Zhu Ymn. BEPAS-a lfe cycle buldng envronment performance assessment model, Buldng and Envronment, Vol.4,2006, pp [3]Cheng Mn, Wu Tanyan. Research on the buldng energy consumpton and savng based on lfe-cycle analyss[j]. Industral Constructon, 2009,39(7):-3. [4]Zhenxng Jn, Yong Wu, Bazhan L, Energy effcency supervson strategy selecton of Chnese large-scale publc buldngs. Energy Polcy, Vol.37,2009,pp [5]Chna natonal bureau of statstcs. Chna statstcs yearbook. Bejng: Chna Statstcs Press, ISBN: