Energy consumption of RC buildings during their life cycle

Transcription

1 Energy consumpton of RC buldngs durng ther lfe cycle Ö. Bozdağ & M. Seçer Dokuz Eylül Unversty, Izmr, Turkey ABSTRACT: Studes on the total energy use durng the lfe cycle of renforced concrete buldngs are desrable, consderng the urgent necessty to save energy. Lfe cycle of buldngs ncludes dfferent phases whch are the manufacture of the buldng materals, transportaton, constructon of the buldng, occupancy, renovaton, demolton and removal of the materals from debrs. However, there have been few studes are on the total energy use durng the lfe cycle of buldngs. Researches are manly focused on the energy use for buldngs durng ther perod of use. In the present study, the total energy use of ordnary renforced concrete buldngs n Izmr durng ther lfe cycle s nvestgated and ther energy consumptons are calculated for all temporal phases separately. INTRODUCTION The optmum use of lmted energy sources s one of the most vtal ssues for the modern countres. The ncrease n global warmng, energy resource depleton, and local and regonal polluton have detrmental effects on the ecologcal system snce the late 980s. Buldngs have a great role n global and local energy consumpton of the world and energy savngs n buldngs has gan mportance n last decades. Energy used durng the lfespan of buldngs conssts of consumed energy n producton, management and destructon phases (Fg. ). Producton energy may be dvded nto three parts: materal manufacturng, transportaton and erecton energy. Management energy s the energy used durng occupaton and renovaton of buldng. Occupaton energy manly ncludes the energy used for heatng, ventlaton and household electrcty. Obsolescence, natural or man-made catastrophe and out-of-fashon facltes causes the renovaton of buldng. Destructon energy s the energy use for the demolton and removal of debrs processes at the end of the lfespan of buldngs. There have been few studes are on the total energy use durng the lfe cycle of buldngs. Researches on the energy use for buldngs are manly focused on management phase. In the present study, the total energy use of three ordnary renforced concrete buldngs n Izmr durng ther lfe cycle s nvestgated and ther energy consumptons are calculated for all temporal phases separately. Therefore, t s often useful for a desgner to have a tool, whch wll allow a buldng to be assessed at the desgn stage, so that varous desgn optons and strateges can be compared wth one another based on the performance over ther useful lfetme. 433 Best Papers SB07 Regonal Polcy Forward

2 Fgure. Lfe cycle phases of a buldng 2 METHOD Lfe cycle of buldng ncludes the manufacture of buldng materals, transportaton of buldng materals to constructon ste, erecton of buldng, occupancy, renovaton, demolton and removal phases. Energy demand durng the lfe cycle of the buldng lfe cycle (kwh), s the sum of the dfferent energy demands durng the dfferent phases and calculated as below. lfe cycle = manufactur e + transporta ton, producton + erecton + occupaton + renovaton + () + + transporta ton, renovaton demoluton transporta ton, removal Snce there s not enough data about the energy ganed by reuse, recyclng or combuston, the value of the left over products are neglected. The procedure used for calculatng energy consumpton n all these phases s descrbed below. 2. Energy consumpton n producton phase Energy s requred for manufacturng any constructon materal. The manufacturng energy requrements of some constructon materals are presented n Table. The waste of each materal produced durng the erecton of the buldng s also shown n the same table. The waste s expressed as a waste factor w. The energy requrement for manufacturng any the buldng materal manufacture (kwh) can be calculated as follows (Adalberth, 997): = n manufactur e = ( ± w 00) m M (2) where n = number of materals, = the materal of concern, m = amount of the buldng materal (ton), w = the factor for waste of the buldng materal produced n erecton (%), and M = energy requred for manufacturng the buldng materal (kwh/ton). Table. Energy use for buldng materals Materals M (kwh/ton) * w (%) ** Renforced Concrete Plan Concrete 20 0 Tles and clnkers Glass PVC Polystyrene Coatngs: Pants and lacquers Steel Electrc wres, copper Whte goods, 0 kwh/per tem - - * Source: Andersen et al., 993 ** Source: Larsson, Best Papers SB07 Regonal Polcy Forward

3 Energy s requred for movng constructon materals from one place to another. Transport takes place from the manufacturer to the buldng ste, when the buldng s beng erected or renovated. The transportaton of raw and sem-manufactured materals s ncluded to the manufacturng energy. Varous energy uses assocated wth dfferent knds of transportaton s shown n Table 2. Table 2. Energy use for transportaton of buldng materals Transportaton T c (kwh/ton km) * Long Dstance Road (dstances km) 0.28 Long Dstance Road (dstances km) 0.75 * Tllman et al., 99 The energy use for transportng the buldng materals transportaton,erecton (kwh) to and from the buldng ste n erecton can be calculated as follows (Adalberth, 997): transporta ton,erecton n = ( + w 00) d Tc = m (3) where n = number of materals; = the materal concerned; m = amount of the buldng materal (ton); w = factor for waste of the materal produced durng erecton of the buldng (%); d = dstance from the manufacturer of materal to the buldng ste (km) and T c = energy requred for the conveyance concerned (kwh/ton km). Energy s needed for many erecton stages of a buldng such as for nstance dryng and dranage, the heatng of sheds and of the buldng tself, electrcty for lghtng purposes and for machnery, and so on. The energy pertanng to the varous processes are gven n Table 3. Table 3. Energy consumpton for varous processes Materals P * Dryng of standard concrete on buldng ste 44 kwh/ton Dryng of concrete element 25 kwh/ton Excavaton and removal of sol 32 kwh/m 3 Smoothng of sol 3 kwh/ton Lghtng of constructon object 26 kwh/m 2 usable floor area * Source: Andersen et al., 993 The energy use for dfferent processes n erecton of a buldng erecton (kwh) s estmated as follows (Adalberth, 997): m = p P (4) erecton k = k k where m = number of processes; j = the type of process; p = the amount of the process j (ton, m 3 or m 2 usable floor area); and P j = energy requred for the process j (kwh/ton, kwh/m 3 or kwh/m 2 usable floor area). 2.2 Energy consumpton n management phase Management ncludes occupaton and renovaton phase of a structure. Energy used n occupaton has many components but n the present study only heatng and electrcty energy are consdered. The heatng energy demand of buldngs s calculated accordng to Turksh Standard TS825-Thermal Insulaton of Buldngs (999). Due to there s no detaled nvestgaton on electrcty consumpton for example buldngs, general consumpton values are used. 435 Best Papers SB07 Regonal Polcy Forward

4 Accordng to Turksh Republc Prme Mnstry State Plannng Organzaton (2003), annual electrcty consumpton s 3000 kwh/person for Izmr regon. The energy needed durng the occupaton phase, occupaton (kwh), s obtaned by multplyng the energy use per year, occupaton (kwh/year), by the lfe-span of the buldng concerned, n ths case years: occupaton =. occupaton,annual (5) When the energy use durng the renovaton of a buldng s calculated, some assumptons regardng the lfe-span of the varous constructon materals have to be made. Lfe-spans of some materals are gven n Table 4. Table 4. The lfe spans of constructon materals Lfe span of buldng Lfe span (annual) * Lfe span of buldng Frame (External walls, nternal walls, nsulaton) Parquet floorng Water ppes and electrc wres Ventlatng channels Facng: wooden panelng Wndows and doors Wardrobes and cupboards Roofng tles and dranppes Plastc carpetng Water heater Whte goods Pantng and wallpaperng * Source: SABO, The energy use for producng the buldng materals durng the renovaton, renovaton (kwh), s estmated as follows (Adalberth, 997): n = m lfe span of a buldng ( + w 00) M lfe span of materal renovaton (6) = The energy use, transportaton,renovaton (kwh), for transportng the buldng n renovaton s estmated as follows (Adalberth, 997): n lfe span of a buldng transporta ton,renovaton = m + lfe span of materal = ( + w 00) ( d 20) T c (7) 2.3 Energy consumpton n destructon phase Destructon phase ncludes demolshng and removng debrs from the buldng ste. The energy use for demolshng the buldng demolton, (kwh), s estmated as follows (Adalberth, 997): m = p P (8) demolton k= k k where m = number of processes; j = the type of process; p = the amount of the process j (ton, m 3 or m 2 usable floor area); and P j = energy requred for the process j (kwh/ton, kwh/m 3 or kwh/m 2 usable floor area). The energy use, transportaton, demolton (kwh), for transportng the buldng n renovaton s calculated as follows: 436 Best Papers SB07 Regonal Polcy Forward

5 transporta ton, demolton n = ( + w 00) 20 Tc = m (9) 20= the assumed dstance from the buldng ste to the waste dsposal ste (km); and T, = energy requred for the conveyance concerned (kwh/ton km). 3 NUMERICAL EXAMPLE In the present study, the energy use of three renforced concrete dwellng buldngs durng ther lfespan s nvestgated. Floor plans of these buldngs are shown n Fgure 2, Fgure 3 and Fgure 4. Fgure 2. Buldng Plan Fgure 3. Buldng Plan Best Papers SB07 Regonal Polcy Forward

6 Fgure 4. Buldng Plan 3 All buldngs are n Izmr regon. Some characterstc propertes of buldngs are summarzed n Table 5. Table 5. Propertes of buldngs Buldng Buldng 2 Buldng 3 Floor Area (m 2 ) Number of floors Number of apartments Number of resdents * Source of heat Dstrct Heatng Dstrct Heatng Dstrct Heatng Heatng system Radators Radators Radators * The number of resdents s estmated accordng to Turksh Prme Mnstry State Plannng Organzaton Reports (2003). In the cty of Izmr, approxmately 3.6 person lvng n each apartment. The amounts of materals consumed for erecton of each buldng was calculated. The quanttes of the buldng materals are substtuted nto Equaton 2 n order to determne manufacture energy of materals for each buldng and calculated energes for materals are presented n Fgure 5. Only heatng and electrcty energes are consdered n calculatng occupaton energy of buldngs. The heatng energy demand of buldngs was calculated accordng to Turksh Standard TS825 (999). There s no detaled nvestgaton on electrcty consumpton for buldngs. For ths reason, the approxmate energy consumpton value publshed by Turksh Republc Prme Mnstry State Plannng Organzaton s used. Accordng to ths organzaton report, electrcty consumpton s 3000 kwh per person for Izmr regon. Ths value s multpled by number of resdents and annual electrcty consumpton of each buldng s calculated. 438 Best Papers SB07 Regonal Polcy Forward

7 Plastcs 2% Whte Goods 3% Others % Polystren 2% Plastcs 2% Whte Goods 2% Others % Polystren 3% Tles and Brcks 5% Glass 2% Tles and Brcks 6% Glass % Steel 30% Concrete 55% Steel 28% Concrete 57% Buldng : manfacture = 066 kwh/m 2 for years Buldng 2 : manfacture = 202 kwh/m 2 for years Plastcs 2% Whte Goods 4% Others % Polystren 4% Tles and Brcks 6% Glass 2% Steel 30% Concrete 5% Buldng 3: manfacture = 396 kwh/m 2 for years Fgure 5. Energy used for manufacture the constructon materals for lfe cycle of buldngs The energy used n producton, management and destructon phases are calculated and summarzed n Table 6. It s seen from ths table that the most energy s consumed n management phase for all buldngs. Results also show that the total energy consumpton of each buldng s 62, 57 and 82 kwh/(m 2.year) respectvely. Table 6. Energy use durng lfe cycle of buldngs Buldng Buldng 2 Buldng 3 Phases kwh/m 2 % kwh/m 2 % kwh/m 2 % Producton Manufacture Transportaton Erecton Management Occupancy, years Renovaton Destructon Demolton Removal Total kwh/(m 2. years) Total kwh/(m 2.year) Best Papers SB07 Regonal Polcy Forward

8 4. CONCLUSIONS In ths paper, the total energy use durng the lfe cycle of the three buldngs n Izmr regon s nvestgated. The purpose s to gan an nsght nto total energy use for buldngs durng ts lfe cycle. The energy used for concrete and steel s 85%, 85% and 8% of the buldngs and these are composng the man part of the manufacturng phase. The results show that management phase s the hghest energy consumpton phase for all buldngs. For ths reason, usng less heatng and electrcty energy s very mportant for mnmzng lfe cycle energy. It s also obtaned that total energy use of buldngs are 62, 57 and 82 kwh/(m 2.year) and energy use s ncreasng when the total useful area of buldng s decreasng. REFERENCES Adalberth, A Energy use durng the lfe cycle of buldngs: A Method. Buldng and Envronment. Vol. 32, No. 4, pp Andersen, S., Dnesen, J., Hjort Knudsen, H. & Wllendrup, A Lvscyklus-baseret bygnngsprojekterng. Report no 224, Dansh Buldng Research Insttute, Hersholm, Denmark. Larsson, B Materalforbruknng Pa Byggarbetsplatsen. Buldng Economcs And Constructon Management, Chalmers Unversty Of Technology, Gothenburg, Sweden. SABO Mantenance norm. Organzaton For Muncpal Housng Companes, Stockholm, Sweden. SPO, Development report for cty of Izmr. Turksh Republc Prme Mnstry State Plannng Organzaton. Avalable: Tllman, A.-M., Baumann, H., Erksson, H. and Rydberg, T. 99. Packagng and the envronment lfe cycle analyses of selected packagng materals quantfcaton of envronment loadngs. SOU 99:77, Chalmers Industrteknk, Chalmers Teknkpark, Gothenburg. Sweden. TS Thermal Insulaton of Buldngs. Turksh Standard Insttute. Ankara. Turkey. 440 Best Papers SB07 Regonal Polcy Forward