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Anend-useenergyanalysisinaMalaysianpublichospital

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Energy 35 (2010) 4780e4785

Contents lists avai

Energy

journal homepage: www.elsevier .com/locate/energy

An end-use energy analysis in a Malaysian public hospital

R. Saidur a,b, M. Hasanuzzaman a,b,*, S. Yogeswaran a, H.A. Mohammed c, M.S. Hossain a,b

aDepartment of Mechanical Engineering, University of Malaya, Faculty of Engineering, 50603 Kuala Lumpur, MalaysiabCentre of Research UMPEDAC, Level 4, Engineering Tower, Faculty of Engineering, University of Malaya, 50603 Kuala Lumpur, MalaysiacDepartment of Mechanical Engineering, College of Engineering, Universiti Tenaga Nasional, Km 7, Jalan Kajang-Puchong, 43009 Kajang, Selangor, Malaysia

a r t i c l e i n f o

Article history:Received 11 February 2010Received in revised form20 August 2010Accepted 9 September 2010

Keywords:Energy savingsPublic hospitalEmission reduction

* Corresponding author. Department of MechanicMalaya, Faculty of Engineering, 50603 Kuala Lumpur,79677611; fax: þ603 79675317.

E-mail addresses: hasan.buet99@gmail.com,hasan@u

0360-5442/$ e see front matter � 2010 Elsevier Ltd.doi:10.1016/j.energy.2010.09.012

a b s t r a c t

The commercial sector consumes 8e50% of the total energy consumption for a few selected countriesaround the world. An energy audit was conducted in a Malaysian public hospital to identify energy usingequipment and their energy consumption breakdown. Different energy saving measures have beenidentified and applied for electrical motors used in this hospital. It was estimated that this hospitalconsumed about 19,311 MW h for the year 2008. It was also estimated that about 212 MW h, 250 MW hand 317 MW h of annual energy can be saved using energy-efficient motors at 50%, 75% and 100% loads,respectively. In addition, use of variable speed drives are expected to save 1735 MW h, 4048 MW h and6361 MW h of annual energy consumption for 20%, 40% and 60% speed reductions, respectively. It wasfound that the payback period for using high efficiency motors at different loads is less than a year whichis economically very viable. However, the use of variable speed drives was found to be economicallyviable for larger motors for higher speed reductions. The study also found that a sizeable amount ofemissions can be reduced for the different energy savings measures applied for electrical motors.

� 2010 Elsevier Ltd. All rights reserved.

1. Introduction

Energy use in commercial and residential buildings has steadilyincreased by between 20% and 40% in developed countries for thelast decade [1]. The building sub-sector consumed approximately8e50% of total energy for few selected countries [2]. Bujak [3]reported that about 40% of total energy is consumed by residen-tial and public buildings in the EU (European Union). Yang et al. [4]reported that energy usage in office buildings is about70e300 kWh/m2 per annum, 10e20 times that of residentialbuildings. The commercial sector accounts for approximately 32%of total energy consumption in Malaysia as reported by Saidur [2].Chirarattananon et al. [5] revised the requirements and proceduresfor energy conservation in offices, hotels, hospitals, departmentstores, schools, supermarkets, condominiums and other buildingsin Thailand. The authors reported an average energy intensity of148.8 kWh/m2 for a hospital in Thailand. An efficient and effectiveheating, ventilating and air-conditioning system that consumesenergy is required to maintain a proper indoor environment ina hospital’s operational and surgical theatres [6e8].

al Engineering, University ofSelangor, Malaysia. Tel.: þ603

m.edu.my (M. Hasanuzzaman).

All rights reserved.

Efficient use of energy can be considered as one of the potentialand cost-effective ways of solving global energy and environmentalproblems [9]. Energy efficiency should be considered as one of themost important policies and strategies in developed countries[10,11]. The intelligent planning of energy supply to differentcategories of buildings is an important aspect to conserve energyand protect the environment as the building sector consumesa major share of total energy use [12].

The majority of the equipment in a commercial building (i.e.a hospital, office, supermarket, etc) is operated by motors ora motor-driven system. In the literature, it was reported thatapproximately 31e75% of total energy is consumed by electricalmotors for a few selected countries around the world [13]. There-fore, electrical motors are targeted in this study to reduce theirenergy consumption along with emission reduction associatedwith energy savings.

Future energy challenges, emissions from burning fossil fuelsand global warming are demanding our focus on energy savings atvarious energy using sectors. An effective way to overcome thesechallenges is to improve the efficiency of energy using equipment[14]. Bizzarri andMorini [15] studied the new technologies (i.e. fuelcells, photovoltaic systems, and solar thermal systems) for aneffective energy retrofit for hospitals in Italy. The authors reportedthat these retrofit policies could offer a significant greenhouse gasemission reduction. Bizzarri and Morini [16] studied greenhouse

Nomenclature

AECa annual energy consumption of equipment (MWh)AES annual energy savings (MWh)c average energy cost (RM/kWh)Ca capacity of equipment (kW)Eee energy-efficient motor (%)EI energy intensity (kWh/m2)EMi total amount of emission (ton)EMp

n fossil fuel emission for a unit of electricitygeneration of fuel type n (ton)

EPi electricity production in the year i (GWh)Esrd standard efficiency motor (%)ESVSD energy saving with the application of VSDHavg_uage average usage hour (hr)hp motor rated horsepower (hp)hr annual operating hour (h)L load factor (either 50%, 75% or full load)PEi

n percentage of electricity generation in a year i of fueltype n recommended

SSR percentage energy savings associated with speedreduction

TFA total floor area of the hospital (m2)Sn

iAEC sum of energy consumption of equipment i to n

Table 1Data summary of an audited hospital.

Parameter Amount

Total floor area, m2 82,683Operation hours for building A, h 8760Operation hours building B, h 3285

Table 2Number of electric motors and their capacities in Buildings A and B.

Motor HP Number of motorsin Building A

Number of motorsin Building B

0.033 0 170.25 0 140.33 0 41 0 11.5 6 12 6 13 18 44 9 405 26 15.5 5 46 3 07.5 8 810 8 1015 11 920 7 125 10 1530 0 140 0 650 1 060 5 0

R. Saidur et al. / Energy 35 (2010) 4780e4785 4781

gas reduction and primary energy savings in a hospital. The authorsfound that fuel cells appear to be the most promising option toimprove efficiency and will save 4925 MWh of primary energy.Schijndel [17] studied the optimal operation of a hospital powerplant and found energy savings of 260 GW h/year. Jeon et al. [18]investigated the performance of a hybrid cooling system andfound that about 13% of energy can be saved with proper control ofthe temperature of the chilledwater system. Use of energy-efficientmotors and variable speed drives to match the load requirementshas been found to be an economically viable solution to reducemotor energy consumption [13]. Teitel et al. [19] carried out anexperiment using a variable frequency drive and found that about64% of energy can be saved by matching the load.

The aim of this study is to analyse energy use, energy savingsand corresponding emission reductions for the energy usingequipment in a public hospital in Malaysia. An emphasis is given onelectric motors as the literature finds they consume a sizeableamount of energy. The authors feel that this study is necessary andimportant to initiate benchmarking for energy consumption ina public hospital since it is in operation 24 h a day in order to fulfillthe medical demands of a growing population.

2. Methodology

This section explains data collection procedures, formulations ofenergy consumption, energy intensity, energy savings, paybackperiods and emission reductions associated with energy savings.These are elaborated below.

2.1. Data collection and building characteristics

A walk-through energy audit was conducted to identify perti-nent parameters such as capacity of energy using equipment (i.e.motor, lightings, pumps, etc), their number and operating hours,annual electric bills, space temperatures, buildings characteristicsand floor spaces. This audit was conducted in a public hospitalconsisting of Buildings A and B. Building A is a T-shaped eight storey

unit. It operates continuously for 24 h, seven days a week. BuildingB operates five days a week from 8am to 5pm. Building B beganoperating in 2003. It is a stand-alone building with three storeysand houses various clinical departments. The first level is used forthe cafeteria, pharmacy and clinics. The second level is used for eye,ear, nose and throat clinics. Endoscopy and operation theatres arealso situated on this level. The third level is used for the auditorium,library and specialist offices.

A few rooms in Building B are operated 24 h a day to keepsensitive equipment andmedical supplies cool and dry. These areoptometry rooms where sensitive eye-scan scopes are stationed.A pharmacy that stores medical supplies in refrigerators is alsostationed in this building. Sensitive equipment is kept cool anddry to avoid fungus growth and to maintain a maximum cali-brated condition. Table 1 shows a summary of characteristics ofthe hospital. Table 2 shows the number of electric motors andtheir capacities used in Buildings A and B. These motors aremanufactured by Headline Electric Co. Ltd, Teco Electric andMach. Pte. Ltd.

2.2. Formulations of energy consumption and energy intensity

Annual energy consumption by electric equipment can be esti-mated using Equation (1).

AECa ¼ Ca � hr � L� 0:001 (1)

An energy intensity which is an indicator of energy performance ofa building can be estimated by using Equation (2).

EI ¼

PniAEC

TFA(2)

Table 3Efficiency for standard and high efficiency motors at different loads.

Motor HP Incremental cost(Ringgit Malaysia)

Load (50%) Load (75%) Load (100%)

Estd Eee Estd Eee Estd i

1.5 80 76.04 80.06 78.03 81.28 78.50 82.552 86 77.20 80.02 79.29 83.07 81.00 83.553 192 77.78 82.44 79.87 84.55 81.50 85.014 195 81.07 83.69 82.39 85.24 82.90 85.965.5 218 81.15 84.35 84.73 86.50 85.30 87.757.5 291 84.07 85.51 86.23 87.58 86.61 89.5015 320 84.92 88.32 86.45 89.85 87.94 90.4420 355 86.03 88.51 87.58 91.05 88.95 91.6425 595 87.61 90.26 88.39 91.66 89.50 91.80

Table 5Emission factors for fossil fuel for electricity generation.

Fuels Emission factor (kg/kWh)

CO2 SO2 NOx CO

Coal 1.18 0.0139 0.0052 0.0002Petroleum 0.85 0.0164 0.0025 0.0002Gas 0.53 0.0005 0.0009 0.0005Hydro 0.00 0.000 0.0000 0.0000Others 0.00 0.000 0.0000 0.0000

Table 6Energy consumption and monthly bill for Buildings A and B in 2008.

Month Tariff(RinggitMalaysia)

Building A Building B

Energyconsumption(kWh)

Energy bill(RinggitMalaysia)

Energyconsumption(kWh)

Energy bill(RinggitMalaysia)

Jan 0.234 1,210,407 283,235 392,627 91,875Feb 0.234 1,087,548 254,486 389,246 91,084Mar 0.234 1,186,218 277,575 413,648 96,794Apr 0.234 1,196,367 279,950 400,594 93,739

R. Saidur et al. / Energy 35 (2010) 4780e47854782

2.3. Mathematical formulations to estimate energy savings by usinga high efficiency motor

A high efficiency motor uses low-loss materials to reduce coreand copper losses. Therefore, it generates less heat and requiresa smaller and more energy-efficient cooling fan. The most popularapproach is demand-side management, one aspect of which is toimprove efficiency to offset load growth. These facts led electricmotor manufacturers to seek methods for improving the motorefficiency,which resulted in a newgeneration of electricmotors thatare known as energy-efficient electric motors. Several leadingelectric motor manufacturers in the USA and Europe, have devel-oped energy-efficient electric motors [20]. High efficiency motorstypically cost 10e25% more than standard motors [21]. Annualenergy savings attained by replacing standard efficient motors withhigh-energy efficiency motors can be estimated by using data inTable 3 and Equation (3) [2,14,21].

AES ¼ 0:746� hp� L� hr ��

1Estd

� 1Eee

�� 100 (3)

2.4. Energy savings by using variable speed drives

Electricmotors are over 90% efficient when running at their ratedloads.However, theyare very inefficient at load following, or runningon part loads. Normally, motors operate more efficiently at 75% ofrated loadandabove.However,motorsarevery inefficientwhentheyare operated at lower than 50% of rated load. Due to the reactivecurrent increase, power factors are also decreased [22]. In such cases,variable speed drive can be used to match load requirements so thatenergy can be saved. The study carried out by Ref. [23] found thatvariable speed drives are good candidates to match the loadrequirements and consequently will save a huge amount of energy,lower utility bills and protect the environment from harmfulpollutants. Using Equation (4) and data from Table 4, energy savingswith the application of variable speed drive can be estimated as:

ESVSD ¼ hp� Havg usage � SSR (4)

2.5. Mathematical formulations of bill savings and payback period

Using data taken from Ref. [21] and Equations (5) and (6), billsavings and payback periods for using high efficiencymotors can be

Table 4Potential savings from variable speed drive [2].

Average speed reduction (%) Potential energy savings (%)

20 1540 3560 55

estimated. The incremental cost of the variable speed drive hasbeen taken from Ref. [2].

Bill savings ¼ AES� c (5)

Simple payback period ðyearsÞ ¼ Incremental costAnnual dollar savings

(6)

2.6. Formulations of emission reductions associated with energysavings

Emission reductions associated with the use of high efficiencymotors and variable speed drives are estimated based on theemission factor per unit energy use taken from Table 5. Equation (7)can be used to estimate emission reductions associatedwith energysavings for the two energy saving strategies [24]:

EMi ¼ EPi�PE1i � Em1

p þ PE2i � Em2p þ PE3i � Em3

p þ.

þ PEni � Emnp

�ð7Þ

3. Results and discussions

3.1. Energy consumption and monthly bills

Monthly energy consumption and bills for Buildings A and B forthe year 2008 are presented in Table 6. It is observed from thebilling data that the energy demand for Building Awas quite high inthe month of May in 2008. A possible reason is that it was thehottest month of the season. Therefore, to achieve a comfortablelevel in clinics and office areas, nearly every unit of an air-condi-tioning system had to run at its maximum capacity. Energyconsumption was found to be comparatively low in the month ofJune in 2008. This is due to lesser admission of patients in thismonth. This consequently lowered the usage of the biomedical

May 0.234 1,274,193 298,161 429,246 100,444Jun 0.234 1,206,120 282,232 367,826 86,071Jul 0.296 1,238,965 366,734 396,789 117,450Aug 0.296 1,231,219 364,441 433,894 128,433Sep 0.296 1,174,254 347,579 399,268 118,183Oct 0.296 1,209,411 357,986 423,011 125,211Nov 0.296 1,194,318 353,518 426,077 126,119Dec 0.296 1,188,237 351,718 441,519 130,690

Fig. 1. Electrical consumption breakdown.

Table 7Energy and bill savings by using energy-efficient motors at different loadings forBuildings A and B.

HP Qty Energy savings (MWh) Bill savings (Ringgit Malaysia)

50% Load 75% Load 100% Load 50% Load 75% Load 100% Load

1.5 7 2.02 2.44 3.93 611 711 11562 7 1.91 3.61 3.08 563 1061 9303 22 13.87 19.83 19.39 4112 5881 57334 49 12.07 19.13 26.94 3586 5651 79745 27 20.19 13.59 23.43 5963 4030 69225.5 9 4.31 4.62 7.36 1287 1366 22037.5 16 5.37 7.27 14.58 1598 2140 432210 18 19.39 18.36 18.8 5743 5434 556815 20 31.9 28.78 42.13 9454 8528 12,47020 8 15.7 23.76 31.74 4646 7027 939325 25 42.8 57.78 76.03 12,661 1709 22,514

Table 8

R. Saidur et al. / Energy 35 (2010) 4780e4785 4783

equipment. This building was built in 1984 and it has a normal non-mechanical ventilation system with ceiling fans. It also hasa mechanical ventilation systemwith a centralised air-conditioningsystem. Split type air-conditioning systems were installed in the1990s due to temperature rises in clinics, offices and laboratories.Almost all of the laboratories in Building A were air-conditionedand equipped with freezers and refrigerators to keep medicine andsamples in good condition. This might be another factor that raisedenergy consumption during themonth of May. It was observed thatthe energy bills start increasing from July 2008 even though energyconsumption remained the same. This is because of a change in therate of the electric tariff from Ringgit Malaysia 0.234 k/Wh toRinggit Malaysia 0.296/kWh. The tariff was changed by theGovernment due to an increase in global crude oil price.

3.2. End-use electricity usage

In this study, emphasis was given to find the end-use energyconsumption in an audited hospital for the year 2008. Based ona walk-through energy audit data analysis, it was found thatlighting consumed the highest amount of energy (36.3%), followedby biomedical equipment (34.5%), office equipment (8.9%), motor-ised equipment such as electric patient beds (8.7%), communicationdevices (4.1%), ceiling fans (3.45%), refrigerators (2.2%), audio-visualequipment such as television sets (2.1%), electrical appliances(1.2%), kitchen utilities (1.1%), electric doors (0.9%), pumps (0.6%),and other equipment (0.3%). Lifts, cameras, CCTVs, compressors,dumbwaiters, and conveyor systems were included in other cate-gories of equipment. Fig. 1 shows the breakdown of energyconsumption of the equipment used in this hospital. Since lightingand biomedical equipment consume a major fraction of the totalenergy consumption, these devices may be targeted for efficiency

Fig. 2. Energy intensity for commercial buildings in Malaysia and other countries [1,2].

improvement to reduce their energy consumption. However, thehighest priority is given to treating and curing patients. For medicalpractitioners, energy efficiency is given a low priority. Therefore, itis more practical to target motor-driven equipment for efficiencyimprovement so that energy consumption of this equipment can bereduced along with environmental pollution prevention.

3.3. Energy intensity

Using Equation (2), energy intensity has been calculated andfound to be 234 kWh/m2. Energy intensities of commercial build-ings for a few selected countries are also presented in Fig. 2 tocompare with the present hospital’s energy intensity. It is observedthat the energy intensity of this hospital is quite high compared toother commercial buildings in Malaysia and other parts of theworld. It is also observed that Malaysian commercial buildings aremore energy efficient than hospitals. Even in Malaysia, the Ministryof Energy, Posts and Telecommunications have already built a lowenergy office building whose energy intensity is about 114 kWh/m2

[25]. To encourage and practice energy efficiency in office buildings,the Malaysian Energy Centre is also in the process of constructinga low energy office building. Therefore, energy savings strategiesmay play a crucial role in reducing a hospital’s energy consumption.Consequently this will reduce the energy intensity of a hospital.

3.4. Energy savings, bill savings and payback period by using a highefficiency motor

Energy savings, bill savings and payback period has beencalculated by using Equations (3), (5), (6) and the results are pre-sented in Tables 7 and 8 for both buildings. It was estimated that212 MWh, 249 MWh and 317 MWh of energy can be saved formotor loadings of 50%, 75% and 100%, respectively. This will

Payback (year) periods of Building A and Building B for using energy-efficientmotors.

Motor HP Building A Building B

50% Load 75% Load 100% Load 50% Load 75% Load 100% Load

1.5 0.22 0.19 0.12 0.6 0.51 0.322 0.28 0.15 0.17 0.75 0.4 0.453 0.13 0.09 0.09 0.34 0.24 0.244 0.4 0.25 0.18 1.07 0.68 0.485 0.27 0.4 0.23 0.72 1.07 0.625.5 0.34 0.29 0.18 0.83 1.11 0.637.5 0.63 0.47 0.23 1.67 1.25 0.6210 0.2 0.22 0.21 0.54 0.57 0.5615 0.22 0.23 0.16 0.6 0.81 0.5420 0.13 0.09 0.07 0.36 0.27 0.1925 0.3 0.24 0.18 1.22 0.83 0.62

Table 9Energy savings and bill savings by using a variable speed drive at a certain speedreduction.

HP Energy savings Bill savings

(MWh) forspeed reduction

(Ringgit Malaysia) forspeed reduction

20% 40% 60% 20% 40% 60%

1.5 9 22 34 2484 5796 91082 12 29 46 3312 7728 12,1443 57 134 210 15,196 35,458 55,7204 94 220 345 24,937 58,187 91,4375 129 302 474 34,256 79,932 125,6075.5 35 82 128 9287 21,669 34,0517.5 81 189 297 21,431 50,005 78,57910 115 269 422 30,522 71,219 111,91515 211 493 775 56,012 130,694 205,37620 145 337 530 38,315 89,402 140,48925 383 893 1404 101,471 236,765 372,059

Table 10Payback periods (year) by using a variable speed drive at a certain speed reduction.

HP Incremental cost(Ringgit Malaysia)

Building A Building B

Speed reduction

20% 40% 60% 20% 40% 60%

1.5 6400 16.4 7.0 4.5 43.8 18.8 11.92 6720 12.9 5.5 3.5 34.5 14.8 9.43 7091 9.1 3.9 2.5 24.3 10.4 6.64 7360 7.1 3.0 1.9 18.9 8.1 5.25 7875 6.1 2.6 1.7 16.2 6.9 4.45.5 8000 5.6 2.4 1.5 14.9 6.4 4.17.5 10,803 5.5 2.4 1.5 14.8 6.3 4.010 10,717 4.1 1.8 1.1 11.0 4.7 3.015 13,363 3.4 1.5 0.9 9.1 3.9 2.520 17,011 3.3 1.4 0.9 8.7 3.7 2.425 19,594 3.0 1.3 0.8 8.0 3.4 2.2

R. Saidur et al. / Energy 35 (2010) 4780e47854784

translate into bill savings of RM 56,180, RM 65,985 and RM 84,005,respectively. It was found in some cases that the payback period isless than one month which is economically viable. The paybackperiod for Building B was found to vary from 0.32 to 1.22 yearswhich shows economic viability. Almeida et al. [26] analysed cost-effectiveness based on the cost of saved energy and showed that itis cost-effective to apply an energy-efficient motor in all capacitiesof motor. The authors found the payback period in their study to beapproximately less than three years. Saidur [13] found the cost forhigh efficiency motors ranged from 10% to 30%, but since a motormay use 75% of its initial cost in electric energy over its lifetime, thesavings potential is great. A return on investment can be obtainedwithin a short period of time (i.e. 2e3 years). Saidur et al. [27] found

Table 11Emission reduction at a certain loading by using a high efficient motor.

Motor HP Emission reduction (kg) for 50% Load Emission reduct

CO2 SO2 NOx CO CO2

1.5 1222 8 3 1 14762 1156 7 3 1 21853 8393 54 21 4 12,0004 7304 47 18 4 11,5765 12,217 78 30 6 82235.5 2608 17 6 1 27967.5 3249 21 8 2 439910 11,733 75 29 6 11,11015 1930 12 5 1 174120 9500 61 23 5 14,37725 25,898 165 63 13 34,962

Total 85,210 545 209 44 104,845

that the payback period for using energy-efficient motors rangesfrom 0.59 to 7.89 years for different percentages of motor loadings.These payback periods indicate the implementation of energy-efficient motors seems very cost-effective as their payback periodsare less than one-third of the motor life (if an average motor life of20 year is considered) particularly for large motors.

3.5. Energy savings, bill savings and payback periods for usinga variable speed drive

Energy savings, bill savings and payback periods for both thebuildings have been calculated by using Equations (4)e(6) and theresults are presented in Tables 9 and 10. It was estimated that1735 MWh, 4048 MWh and 6361 MWh of energy can be saved fora 20%, 40% and 60% speed reduction by using a variable speed drive,respectively. These savings are estimated for both the buildings.This will translate into bill savings of RM 459,775, RM 1,072,720 andRM 1,685,665 for 20%, 40% and 60%, respectively. It was observedthat payback periods are shorter for a higher percentage of speedreduction (for example 60% speed reduction). It was also found thatpayback periods are shorter for larger motors (i.e. 10 HP and above).Saidur et al. [23] found that the payback periods for using a variablespeed drive for larger motors are reasonable (i.e. within 1e3 years).

3.6. Reduction in energy intensity

It is expected that energy savings for two energy savings strat-egies (i.e. use of high efficiency motors and variable speed drives)will reduce energy intensity. Using energy savings data from Table8, a reduction in energy intensity was estimated to be about 1.10%,1.29% and 1.64% at 50%, 75% and 100% loadings, respectively forusing high efficiency motors. A reduction in energy intensity wasfound to be about 8.97%, 20.92% and 32.88% for the speed reductionof 20%, 40% and 60%, respectively for using a variable speed drive.

3.7. Emission reduction

Energy savings measures will not only save energy and bills, butalso the amount of different pollutants. By introducing high effi-ciency motors and variable speed drives, the amount of differenttypes of pollutants have been calculated by using Equation (7) anddata from Table 5. Emission results are then presented in Tables 11and 12 for both the buildings. It was estimated that about 85,210 kg,104,845 kg, and 138,865 kg of CO2 emissions can be reduced byusing energy-efficient motors at 50%, 75% and 100% loadings,respectively. Similarly 654,170 kg, 1,528,652 kg and 1,528,652 kg ofCO2 emissions can be reduced by using a variable speed drive for20%, 40% and 60% of motor speed reductions, respectively.

ion (kg) for 75% Load Emission reduction (kg) for 100% Load

SO2 NOx CO CO2 SO2 NOx CO

10 4 1 2377 16 6 213 6 2 1864 11 5 277 30 6 11,733 75 29 674 29 6 16,302 105 40 953 20 4 14,178 91 35 718 6 1 4454 29 10 228 11 3 8821 57 22 571 27 6 11,376 73 28 611 5 1 2549 16 7 192 35 8 19,206 123 46 10

223 85 18 46,005 293 112 23

670 258 56 138,865 889 340 73

Table 12Emission reduction at a certain speed reduction for using a variable speed drive.

Motor HP 20% Speed reduction 40% Speed reduction 60% Speed reduction

CO2 SO2 NOx CO CO2 SO2 NOx CO CO2 SO2 NOx CO

1.5 5445 36 13 4 13,309 87 33 11 20,568 135 50 172 7263 44 19 6 17,552 106 46 15 27,841 169 72 243 34,492 222 86 16 81,086 522 203 39 127,075 818 318 614 56,883 366 140 31 133,130 857 328 73 208,772 1343 514 1145 78,058 498 192 38 182,741 1167 449 90 286,818 1831 704 1415.5 21,179 138 49 8 49,619 323 114 19 77,453 505 178 307.5 49,007 317 121 30 114,350 739 282 70 179,693 1161 442 11110 69,587 445 172 36 162,773 1040 402 83 255,355 1632 631 13115 12,766 79 33 7 29,827 185 77 15 46,889 292 121 2420 87,739 563 212 46 203,917 1309 494 107 320,701 2059 776 16925 231,751 1477 564 116 540,348 3443 1314 271 849,551 5413 2067 426

Total 654,170 4185 1601 338 1,528,652 9778 3742 793 2,400,716 15,358 5873 1248

R. Saidur et al. / Energy 35 (2010) 4780e4785 4785

4. Conclusions

The following conclusions can be drawn from this study:Based on an end-use energy breakdown, it was found that

lighting uses amajor fraction of total energy consumption (i.e. about36%) followed by medical equipment (i.e. about 34%). The studyfound that the hospital consumed approximately 19,311 MWh ofenergy for the year 2008. The energy intensity of the hospital isfound to be 234 kWh/m2. It was found that approximately 33% (i.e.from 234 kWh/m2 to157 kWh/m2) of energy intensity can bereduced by using a variable speed drive at 60% speed reduction.

It was estimated that 212 MWh, 249 MWh and 317 MWh ofenergy can be saved for motor loadings of 50%, 75% and 100%,respectively. This will translate into bill savings of RM 56,180, RM65,985 and RM 84,005 for motor loadings of 50%, 75% and 100%,respectively. Payback periods were found to be less than a year inmost cases for using high efficiency motors.

It was estimated that the highest amount of energy of about6361 MWh can be saved for 60% speed reduction using a variablespeed drive. The corresponding bill savings for this amount ofenergy saving is found to be RM 1,685,665. It was observed thatpayback periods are shorter for a higher percentage of speedreduction (for example 60% speed reduction). It was also found thatpayback periods are shorter for larger motors (i.e. 10 HP and above)when variable speed drives are used.

Acknowledgement

This research was carried under the High Impact Research Grant(HIRG) scheme. The authors would like to acknowledge the ViceChancellor, University of Malaya for providing the financial supportunder the HIRG scheme.

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