ARTICLE IN PRESS

Energy Policy 37 (2009) 4104–4113

Contents lists available at ScienceDirect

Energy Policy

0301-42

doi:10.1

� Tel.:

E-m

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

Energy consumption, energy savings, and emission analysis in Malaysianoffice buildings

R. Saidur �

Department of Mechanical Engineering, University of Malaya, 50603 Kuala Lumpur, Malaysia

a r t i c l e i n f o

Article history:

Received 16 March 2009

Accepted 29 April 2009Available online 28 May 2009

Keywords:

Energy savings

Energy intensity

Office buildings

15/$ - see front matter & 2009 Elsevier Ltd. A

016/j.enpol.2009.04.052

+603 79674462; fax: +603 79675317.

ail addresses: saidur@um.edu.my, saidur912@

a b s t r a c t

This paper is concerned with the estimation of energy use in office buildings in Malaysia and with the

energy use of major equipment. Energy intensity (EI) – a measure of a building’s energy performance –

is estimated for Malaysia and compared with a number of selected countries. Air conditioners are

shown to be the major energy users (57%) in office buildings, followed by lighting (19%), lifts and pumps

(18%) and other equipment (6%). It is estimated that 77,569 MWh of energy can be saved and a huge

reduction of emissions achieved through the application of advance glazing, compact fluorescent lamps

(CFL), insulation, housekeeping, and by raising thermostat set point temperature of air conditioners, and

reducing EI.

It is also estimated that a very substantial amount of energy can be saved by making use of energy-

efficient motors in building systems with different motor loading percentages.

Finally, it can be shown that the use of variable speed drives (VSDs) and energy-efficient motors

leads to substantial energy savings and an enormous reduction in emissions.

& 2009 Elsevier Ltd. All rights reserved.

1. Introduction

1.1. Global commercial energy and the environmental situation

Energy uses in office buildings is about 70–300 kWh/m2 perannum, 10–20 times that of residential buildings (Yang et al.,2008). The rapid growth of energy use, worldwide, has alreadyraised concerns over problems of supply, the exhaustion of energyresources and severe environmental impacts (ozone layer deple-tion, global warming, climate change, etc.). The global contribu-tions from buildings towards energy consumption, bothresidential and commercial, have steadily increased, reachingfigures between 20% and 40% in developed countries. Growth inpopulation, increasing pressure for building services, and en-hanced comfort levels, together with the rise in time spent insidebuildings, assure the upward trend in energy demand willcontinue in the future. For this reason, energy efficiency inbuildings is today a prime objective for energy policy at regional,national ,and international levels (Lombard et al., 2008).

Globalization, improvement of living conditions in emergingregions and the development of communication networks,promote the life styles of the developed nations and lead topatterns of consumption which raise energy needs to a level

ll rights reserved.

yahoo.com (R. Saidur).

which, without doubt, will exhaust fossil fuel resources and have aserious impact on the environment. In this sense, current energyand socio-economic systems are clearly unsustainable (Lombardet al., 2008).

As the building sub-sector consumes 8–50% of the total energy(as shown in Table 1), efficient use of energy will play a vital rolein reducing energy usage and associated emissions released to theatmosphere. Energy policy plays an important role in anycountry’s sustainable development. Improving energy efficiencyin buildings is one of the most cost-effective measures forreducing carbon dioxide (CO2) emission: one of the main causesof global warming (Lombard et al., 2008; Omar and Mohammed,2004; Jaber et al., 2003; Chow, 2001; Farhanieh and Sattari, 2006;Uchiyama, 2002; Radhi, 2008; Yang et al., 2008; Yamtraipat et al.,2006).

The widespread use of electric motors in air-conditioning,chillers, pumps, air compressors, and lifts in building systems andmotor energy use represents well over half of all electric energyused by industrial, commercial, and institutional facilities. Motorsare found on almost every piece of equipment used to performprocesses in manufacturing, mining, and agriculture. Even piecesof equipment that perform special functions – for example,chillers and air compressors – often have motors as their principalcomponent. The widespread applications of electric motors inalmost every facility, makes them excellent candidates forimprovements to their efficiency and their utilization in machinesand processes. Just a small improvement in electric motor

ARTICLE IN PRESS

Table 1Percentage of commercial sector energy consumption for some selected countries.

Country/region % Sources

USA 18 Lombard et al. (2008)

UK 11

EU 11

Spain 8

Saudi Arabia 50 Omar and Mohammed, (2004)

Jordan 9 Jaber et al. (2003)

Hong Kong 30 Chow (2001)

Iran 38 Farhanieh and Sattari (2006)

Japan 26 Uchiyama (2002)

Bahrain 29 Radhi (2008)

China 35 Yang et al. (2008)

Thailand 33 Yamtraipat et al. (2006)

R. Saidur / Energy Policy 37 (2009) 4104–4113 4105

efficiency can produce significant savings in the energy cost ofoperating a piece of equipment, since the annual cost of operatinga motor can often be five to ten times its original purchase price.

Many motor applications require variable speeds to matchactual loads, making motor control an area of major importance.Adjustable (or variable) speed drives (ASDs or VSDs) are motorcontrol systems that reduce the energy input to a motor when it isnot fully loaded. These ASDs or VSDs can produce substantialsavings in the operational costs of motors, and can often improvethe operation of a system that previously used a motor without aspeed control (Capehart et al., 2005).

Approximately half of UK’s generated electricity is used todrive electric motors (Mecrow and Jack, 2008) and the use ofelectric motors in industrial plants accounts for some 65% of thetotal energy consumption in Turkey (Kaya et al., 2008). This meansthat efficiency improvements to electrical machines can have avery large impact on energy use and it is, therefore, to choose‘‘high efficiency’’ motors. By introducing variable speed to thedriven load, it is possible to optimize the efficiency of the entiresystem, and it is in this area that the greatest efficiency gains arepossible (Mecrow and Jack, 2008).

Considering the importance of energy efficiency in buildings,this study may be useful in the following aspects:

�

Author hopes that it will be beneficial for ASEAN and othercountries to compare the energy consumption of officebuildings, EI, and the amount of emissions released into theatmosphere. � The study also gives an indication of how much Malaysia can

contribute in saving energy and reducing pollution in line withthe global community.

)

� 30000

29000

28000

27000

26000

25000

24000ener

gy c

onsu

mpt

ion

(GW

h

In this analysis different approaches to the saving of energyand the reduction of emissions have been applied and high-lighted. Some of the research reported in the literature reviewconsists of statements of overall trends in consumption andsuggestions of ways to save energy (Omar and Mohammed,2004), but without supporting estimates. In contrast, in thispaper, major energy-consuming equipment has been identi-fied, energy savings measured have been applied, and emis-sions – analyzed in terms of release and reductions – havebeen estimated.

al

�

23000

22000

21000

al c

omm

erci

It is expected that the savings shown in this paper willencourage policy makers to implement energy-saving strate-gies to reduce energy use and atmospheric emissions.

The objectives of the present study are as below:

20000

Tot

2003 2004 2005 2006

�

Fig. 1. Commercial sector energy consumption trends in Malaysia (EC, 2007).

To break down the energy usage of office equipment so thatpotential energy-saving measures can be adopted.

�

To compare energy intensity (EI) and energy usage of officeequipment in Malaysia with that of other countries to bench-mark the energy usage of office equipment. � To estimate energy savings and associated cost savings and

emission reductions with the application of different energy-saving measures for office equipment.

� To calculate the payback period of different energy-saving

measures applied to office equipment.

1.2. The energy situation in Malaysia

There have been growing concerns about energy consumptionand its implications for the environment. High economic growthin Malaysia has led to a dramatic increase in energy consumptionin recent years, particularly electrical energy use in commercialand residential buildings, with the residential and commercialsector consuming almost half of total electricity generated. RisingGDP will increase the demand for electricity, but in differentproportions. Malaysian electricity–GDP elasticity is around 1.5,meaning that for every 1% rise in GDP, electricity consumptionincreases by 1.5%. On the other hand, the main contributor toincreasing atmospheric carbon dioxide concentration is thecombustion of fossil fuels in generating electricity for commercialand domestic uses. The demand for energy is expected to growrapidly not only in the developing countries but in developedcountries too, as they attempt to reach a higher standard living.The effect of this is an increase in the demand for energy and,consequently, in carbon dioxide concentrations in the atmosphere(Anon, 2006). Fig. 1 shows the commercial sector energyconsumption trend in Malaysia.

To reduce energy consumption in the buildings and minimizenegative environmental impacts, it is necessary to take differentmeasures to save energy and reduce environmental pollution. Tocomply with that Malaysian government has already built low-energy office (LEO) buildings whose energy intensity is 114 kWh/m2 (Leo Building, 2005). The Malaysian Energy Centre (PTM) isalso in the process of building zero-energy building to be in linewith global initiatives to reduce environmental pollution. Thegovernment has also put 5% renewable energy usage in its 9thMalaysian plan to encourage the usage of renewable energy toreduce the environmental burden on the atmosphere. In addition,University Science Malaysia’s Centre for Education and Training inRenewable Energy and Energy Efficiency (CETREE) is activelyplaying a role to create awareness of energy efficiency and usageof renewable energy among the end users. There are several NGOs

ARTICLE IN PRESS

Table 2Share of audited energy used compared to total office building energy use in

Malaysia.

Total office building energy use 6090 GWh

Total energy used by 68 buildings 128 GWh

Share of 68 buildings’ energy use compared to total office

building energy use

18.55%

Share of 68 buildings’ energy use compared to total

commercial sector energy use

0.44%

Coomercial, 32%

Residential, 19%Others, 1%

Industrial, 48%

Fig. 2. Statistics of energy uses in Malaysia (EC, 2007).

Table 3Data summary of audited buildings.

Number of building audited 68

Gross floor area, m2 983,000

Total energy consumption, MWh 127,752

Energy intensity (kWh/m2) 130

Table 4Description of Malaysian office buildings.

Building components Description

Walls Typical brick wall

Windows Single clear glazing with aluminum frame

Roof Fiberboard

R. Saidur / Energy Policy 37 (2009) 4104–41134106

working in creating awareness among the different groups ofenergy users to save energy and reduce environmental pollution.This also shows Malaysia’s commitment towards energy efficiencyand environmental concern in line with the global community.

Typically, office buildings consume about 21% of a country’stotal commercial energy use (see Chirarattananon and Taweekun,2003). Based on this assumption, it is estimated that total energyused by Malaysian office buildings is about 6090 GWh (as shownin Table 2.), with the energy used by the 68 buildings analyzed inthis study, consuming about 18.55% of total energy use of officebuildings.

Fig. 2 shows the sectional distribution of total energy use inMalaysia. It has been found that the commercial sector, the secondlargest user, accounts for about 32% of the total energy use inMalaysia.

2. Methodology

This section explains the data collection procedure, formula-tions of energy and EI estimation, energy savings, and emissionreductions. These are elaborated below.

2.1. Data collection procedure and estimation of energy use and EI

The Malaysian Energy Centre (PTM) conducted an energy auditon 68 office buildings in 2006 to collect the following informationto investigate building energy consumption patterns.

�

Age of building. � Types of building. � Weekly usage hours � Aspect ratio. � Gross floor area. � Air-conditioned area. � Occupancy numbers. � Equipment/appliances specification/capacity (kW).

Table 3 shows the summary of some data. Data have beencollected through personal communication with Mohd.Hishamuddin, a PTM officer (PTM, 2006) for this analysis.Table 4 shows the description of Malaysian buildings.

Using energy audit data collected from PTM, energy consump-tion by air-conditioning, lighting, lifts and pumps, and otherequipment have been estimated using the following equation:

AECa¼ UHy

� Ca� LF � 0:001 (1)

where AECa is the annual energy consumption of equipment a inMWh; UHy the yearly usage hours of an equipment a; Ca thecapacity of equipment a, in kW; LF the load factor (62% based onactual billing data, Jayamaha, 2006 who also reported that theaverage load on building facilities is about 60%); 0.001 is the a

factor to convert kWh into MWh.Energy intensity in kWh/m2 has been estimated using the

following equation:

EI ¼

Pni AEC

TFA(2)

whereP

inAEC is the sum of energy consumption of equipment i to

n; TFA—total floor area (m2).

2.2. Formulations of energy savings with the introduction of energy-

saving options

In this section, formulations of energy savings with theapplication of advanced glazing, insulation, housekeeping, andcompact fluorescent lamps (CFL) are shown. These are elaboratedbelow.

Energy can be saved by regulation such as reducing EIcompared to average/base case.

Energy savings as a result of such regulation can be estimatedas

AESEI ¼ ðEIavg � EIefficient_buildingÞ � TFA (3)

where AESEI is the annual energy savings (AES) due to energyintensity improvement.

Annual air conditioner energy savings due to raising thermo-stat set (TS) point temperature can be estimated as

AESts ¼ TECac � %EST22�26 (4)

where TECac is the total ac energy consumption; %EST22–26 is the %energy savings due to raising thermostat set point temperaturefrom 22 to 26 1C.

Energy savings associated with raising thermostat set pointtemperatures is shown in Table 5.

ARTICLE IN PRESS

0

10

20

30

40

50

60

70

80

90

100

10 20 30 40 50 60 70 80 90 100

Pow

er c

onsu

mpt

ion

(%)

Rated speed (%)

Fig. 3. Relationship between motor power reduction and rated speed (Anon,

2008).

Table 5Energy savings by raising thermostat set point temperature.

Temperature (1C) Reduction in energy (%)

22 –

23 6

24 12

25 18

26 24

R. Saidur / Energy Policy 37 (2009) 4104–4113 4107

Annual energy savings using energy-efficient CFL can becalculated as

AESlighting ¼ TEClighting � %ESefficient_lighting (5)

where TEClighting is the total lighting energy consumption in MWh;%ESefficient_lighting the % of energy savings due to efficient lighting.

Annual energy savings with the advanced glazing can beestimated as

AESglazing ¼ TECac � %ESglazing (6)

Annual energy savings by insulation can be estimated as

AESinsulation ¼ TECac � %ESinsulation (7)

where %ESinsulation is the %energy savings due to improvedinsulation.

Annual energy savings by reducing standby energy consump-tion can be estimated as

AESstandby ¼ AECwhole_building � %ESstandby (8)

%ESstandby is the %energy savings due to standby.Annual energy savings by housekeeping can be estimated as

AEShousekeeping ¼ AECwhole_building � %EShousekeeping (9)

%EShousekeeping is the %energy savings due to housekeeping.Bill savings (US$) associated with the energy savings can be

estimated as

BS ¼ AES� UEP (10)

where UEP is the average unit electricity price (US$/kWh).

2.3. Estimating electric-motor energy savings, and emission

reductions

It may be mentioned that energy can be saved in different waysfor different motors used in air-conditioning, lifts, and pumpswith different energy savings strategies. However, the focus of thepresent study is to identify major energy-using equipment andapplying energy-saving options for this major energy-usingequipment and hence electric motors used in building systemshave been identified.

2.3.1. Energy savings by using a high-efficiency motor (HEM)

A high-efficiency motor uses low loss materials to reduce coreand copper losses. Therefore, it generates less heat and requiressmaller and more energy-efficient cooling fans. The most popularis demand-side management, one aspect of which is to improveefficiency to offset load growth. These facts have led electric-motor manufacturers to seek methods for improving the motorefficiency, which resulted in a new generation of electric motorsthat are known as energy-efficient electric motors. Several leadingelectric-motor manufacturers, mainly in USA and Europe, havedeveloped product lines of energy-efficient electric motors(Akbaba, 1999).

Historically, the primary goal in motor manufacture has beento reduce production costs while preserving available power. A

motor can be made more efficient by improvements in design:magnetic cores with plates made of ferrosilicon alloys, better-filled slots using more copper, larger rotor conductors, andimprovements in air-gaps, core heads, fans, and bearings, and inthe dimensional design. High-efficiency motors typically cost10–25% more than standard ones (Garcia et al., 2007).

2.3.1.1. Mathematical formulations to estimate energy savings using

HEMs. Annual energy savings attained by replacing standard ef-ficient motors with high energy-efficient motors can be estimatedusing the methodology described in Garcia et al. (2007)

AES ¼ hp� L� 0:746� hr �1

Estd�

1

Eee

� �� 100 (11)

Annual bill savings associated with the above energy savingscan be calculated as

Savings ¼ AES� c (12)

where savings is the expected annual bill savings (US$);hp ¼ motor rated horsepower; L the load factor (percentage of fullload); hr the annual operating hours; c the average energy cost(US$/kWh); Estd the standard motor efficiency rating (%);Eee ¼ energy-efficient motor efficiency rating (%); 0.746 is theconversion factor from horsepower to kW.

2.3.2. Motor energy savings using variable speed drives

Many building systems are designed to operate at maximumload conditions. However, most building systems operate at theirfull load only for short periods of time. This often results in manysystems operating inefficiently during long periods of time. Mostsuch inefficient operations in buildings are encountered in air-conditioning systems that are normally sized to meet peak loadconditions which are experienced only for short periods of theday. The efficiency of such systems can be improved by varyingtheir capacity to match actual load requirements. As all these arevariable torque applications, the power required (to drive thepumps or fans) varies to the cube of the speed and, therefore, largepower reductions result from small reductions in speed, as can beseen in Fig. 3. The most common method is to modulate the speedof the motors of pumps and fans to vary their capacities usingVSDs (Beggs, 2002).

Variable-frequency drives provide continuous control, match-ing motor speed to the specific demands of the work beingperformed. Variable-frequency drives are an excellent choice for

ARTICLE IN PRESS

Table 8Unit emission released by different sources of energy (Mahlia, 2002).

Table 7Percentage share of fuel used to generate electricity (Mahlia, 2002).

Coal (%) Petroleum (%) Gas (%) Hydro (%)

16.76 2.44 53.2 27.6

R. Saidur / Energy Policy 37 (2009) 4104–41134108

adjustable speed drive users, because they allow operators to fine-tune processes, while reducing costs for energy and equipmentmaintenance (Jayamaha, 2006).

Variable-frequency drives (VFDs) are routinely used to vary apump and fan speed in heating, ventilating, and air-conditioningof buildings. In these applications, speed control is used toregulate the flow of water or air, because it is an energy-efficientway of controlling the flow. The improving performance of theVFDs has resulted from rapidly evolving semiconductor technol-ogy which carries with it improved electrical performancecharacteristics; ability to handle higher power levels; easierprogramming of desired control response, steadily increasingreliability and ruggedness, and smaller size of units (Teitel et al.,2008).

A pump installation is often sized to cope with a maximumpredicted flow, which, may never happen. This principle of oversizing is frequently used in industries, which subsequently leadsto energy loss and damage to parts of the pump installation.

The benefits of using VSD include:

Fuels Emission factor (kg/kWh)

�

TabPot

Ave

10

20

30

40

50

60

Energy cost savings.

CO2 SO2 NOx CO

� Reliability improvements. �

Coal 1.18 0.0139 0.0052 0.0002

Simplified pipe systems (elimination of control valves and by-pass lines).

Petroleum 0.85 0.0164 0.0025 0.0002

� Gas 0.53 0.0005 0.0009 0.0005 Soft start and stop. �

Table 9Unit electricity price for motor energy savings.

Parameters Value

Average electricity cost (US$/kWh) 0.064

Table 10Electric motor operating hours (Jayamaha, 2006).

Motor loading % Operating hours per year

100 163

75 252

50 2385

Table 11Efficiency of energy efficient and standard motors at different loads (Garcia et al.,

2007).

Motor

power, kW

Incremental

price, US$

For 50% load 75% load 100% load

Eestd Eehem Eestd Eehem Eestd Eehem

1 21 70.05 75.28 74.43 79.49 77.00 80.97

1.5 25 76.04 80.06 78.03 81.28 78.50 82.55

2 27 77.2 80.02 79.29 83.07 81.00 83.55

Reduced maintenance.

All amounting to lower life cycle costs.The ASD installations can increase energy efficiency (in some

cases energy savings can exceed 50%), improve power factor andprocess precision, and afford other performance benefits such assoft starting and over speed capability. They also can eliminate theneed for expensive and energy-wasting throttling mechanismssuch as control valves and outlet dampers (Beggs, 2002).

Electric motors are over 90% efficient when running at theirrated loads. However, they are very inefficient at load-following,or running on part loads. Conventional electric motors typicallyuse 60–80% of their rated input energy, even when running at lessthan 50% load. It is very important to select an electric motor ofsuitable power if it is to work efficiently. In general, motors arechosen with large capacities to meet extra load demands, thiscauses motors to work inefficiently at low load. Normally, motorsoperate more efficiently at 75% of rated load and above but, whenoperated lower than 50% of rated load, perform inefficiently, anddue to the reactive current increase, power factors are alsodecreased (Kaya et al., 2008). In such cases, VSDs can be used tomatch load requirements so that energy can be saved.

It may be mentioned that VSD is the best option for variableload. However, it has to be recognized that, in the case of constantload below the rated load, replacement with a lower rated powermotor tends to be more cost-effective than the use of VSD.

From the above studies, it is has been found that VSDs are goodcandidates to match the load requirements and consequently willsave huge amount of energy, utility bills, and protect theenvironment from harmful pollutants.

le 6ential savings from VSD (Personal communication, 2009).

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

5

15

25

35

46

55

2.3.2.1. Mathematical formulations to estimate energy savings using

VSD. There are many ways of estimating the energy savings as-sociated with the use of VSDs for industrial motors for a range ofapplications. This paper uses the methods found in Anon (2008).

Energy use in fans and pumps varies according to the speedraised to the third power, so small changes in speed can result in

3 60 77.78 82.44 79.87 84.55 81.50 85.01

4 61 81.07 83.69 82.39 85.24 82.90 85.96

5 68 81.15 84.35 84.73 86.5 85.48 87.75

7.5 91 84.07 85.51 86.23 87.58 86.61 88.69

10 100 83.85 87.56 86.45 88.9 87.58 89.5

15 111 84.92 88.32 87.58 89.85 87.94 90.44

20 186 86.03 88.51 88.39 91.05 88.95 91.64

30 273 89.43 89.89 90.54 91.73 90.7 91.83

40 371 88.15 90.39 89.86 91.91 90.36 92.85

75 678 88.77 90.86 91.33 92.72 92.44 93.02

100 887 90.03 91.51 92.15 92.84 93.05 93.62

125 1172 89.14 91.47 91.69 93.25 93.56 94.5

ARTICLE IN PRESS

R. Saidur / Energy Policy 37 (2009) 4104–4113 4109

very large changes in energy use. A motor energy savings using aVSD can be estimated as

ESVSD ¼ P � Havg_usage � SSR (13)

ESVSD is the energy savings with the application of VSD; P themotor power (kW); Havg_usage the annual average usage hours; SSR

is the percentage energy savings associated certain percentage ofspeed reduction (taken from Table 6).

Table 6 shows the potential energy savings associated with thespeed reduction using VSDs for industrial motors (Personalcommunication, 2009). These data are used to estimate motorsenergy savings using VSDs.

2.3.3. Formulations of emission reductions associated with the

energy savings

Emission estimation associated with the electricity generationby burning fossil fuels can be expressed by the following equation

Table 15Typical percentage of electrical energy consumption breakdown for few selected count

Country Percentage of electricity consumption (%)

Air-conditioning Lighting

Malaysia 57 19

Indonesia 51 14

Thailand 59 21

Singapore 59 7

Saudi Arabia 50 20

USA 48 22

UK 55 17

Spain 52 33

Table 14Total energy consumption by all equipments and their breakdown (%).

Equipment/appliances MWh/yr % Contribution

AC 72,819 57

Lighting 24,273 19

Lift and pump 22,995 18

Others 7665 6

Table 13Input parameters for cost–benefit analysis of lighting retrofit.

Input parameters CFL Incandescent

Power rating (watt) 18 70

Useful life (hours) 10,000 (4 years) 1500

# lamps for 10,000 hours 1 7

Price (US$) 5.41 10 at 0.379 each

Unit electricity price (US$/kWh) 0.064 0.064

Incremental cost (US$) 0.676 –

Table 12Incremental price for VSD (Anon, 2002).

HP Incremental price, US$

3 2216

5 2461

7.5 3376

10 3349

15 4176

20 5316

25 6123

30 6853

(Mahlia, 2002):

EMi ¼ EPiðPE1i � Em1

p þ PE2i � Em2

p þ PE3i � Em3

p þ � � � þ PEni � Emn

pÞ

(14)

where EMi is the total emission for unit of electricity generation(ton); EMp

n the fossil fuel emission for a unit of electricitygeneration of fuel type n (ton); EPi the electricity production inyear i (GWh); PEi

n the percentage of electricity generation in year i

of fuel type n.Tables 7 and 8 show input data needed to estimate amount of

emissions that can be reduced due to energy savings for differentenergy savings options.

2.4. Economic analysis of energy-saving measures

2.4.1. Mathematical formulations of payback period

A simple payback period for different energy-saving strategiescan be calculated using the below equation:

Simple payback period ðyearsÞ ¼incremental cost

annual dollar savings(15)

Input data needed to estimate energy savings and paybackperiod for different strategies (i.e., use of high-efficiency motors,VSD, and CFL) are shown in Tables 9–13. Average usage hours havebeen collected from energy audit survey data. Efficiency ofstandard and high-efficiency motors have been collected fromGarcia et al. (2007). Incremental costs associated with the usage ofhigh-efficiency motor, VSD, have been collected from Garcia et al.(2007) and Anon (2002). It should be noted here that there is nocomprehensive work on motors in Malaysia, so these data havebeen used to provide some insight into the amount of energy andenergy costs can be saved along with emission reductions.Moreover, motors are manufactured, sold and used around theworld, so data from other countries have also been used in thisestimation.

3. Results and discussion

Using Eq. (1), total annual energy consumption in MWh hasbeen estimated for air-conditioning equipment, lightings, lifts,and pumps and other equipment and presented in Table 14. Alongwith the total energy consumption, % breakdown of thisequipment are shown in the table below.

From Table 14, it has been found that air-conditioningequipment consumes a major portion of the total energyconsumption, followed by lighting, lifts, and pumps and otherequipment. Table 15 compares energy consumption breakdown ofthis equipment for a number of selected countries.

ries.

Reference

General equipment

24 –

26 Elyza et al. (2005)

20 Yamtraipat et al. (2006)

34 http://www.bca.gov.sg, 20/01/2006

30 Omar and Mohammed (2004)

30 Lombard et al. (2008)

28 Lombard et al. (2008)

15 Lombard et al. (2008)

ARTICLE IN PRESS

1200

1000

800

600

400

200

0

Ener

gy s

avin

gs, M

Wh

1 1.5 2 3 4 5 7.5 10 15 20 30 40 75 100125Motor power, kW

50% Load

75% Load

100% Load

Fig. 4. Energy savings for high-efficient motor at different loadings.

70,000

60,000

50,000

, US$

50% Load

75% Load

100% Load

R. Saidur / Energy Policy 37 (2009) 4104–41134110

It has been found that air conditioners are major energy usersin commercial buildings and that lighting and other equipmentare also significant users of energy. Appropriate policy, technol-ogy, and housekeeping are very important to reduce their energyusage and emissions.

Using Eq. (2), energy intensity has been calculated andpresented in Table 16. EI of Malaysia has been compared with anumber of other countries as well. From Table 16, it has beenobserved that EI in Malaysia is lower than USA, Greece, China, andThailand, but higher than Japan. It seems Malaysian officebuildings are more energy efficient than in some other countries.However, there is still room for improvements to reduce furtherenergy consumption by introducing energy savings policy oroptions. Even in Malaysia, the Ministry of energy, posts, andtelecommunications have built a low-energy office building whoseEI is about 114 kWh/m2 (Leo Building, 2005). To encourage andpractice energy efficiency in office buildings, the Malaysian EnergyCentre is also in the process of constructing a low-energy building.It has to be noted that climatic conditions in some parts of USA andEurope are not identical to Malaysian climatic conditions.

It may be mentioned that there are, around the world, differenttypes of regulation (i.e., voluntary, mandatory, and mix mode)aimed at reducing energy use in appliances, machinery andbuildings. Examples include energy-efficiency labels, energy-efficiency standards, and building codes. Many governments useregulations on energy intensity to reduce building energy use. Acomprehensive review of the literature on building energyregulations can be found in Lee and Yik (2004). The energyintensity of a building is influenced by floor area, year built,building fabric and envelope, operating hours, energy price, andowner occupancy, equipment efficiency and the use of aregulatory approach sets the construction industry energyperformance targets in the areas of building envelope andequipment efficiency.

Using Eqs. (3)–(10), energy savings and associated bill savingsfor different energy-saving measures have been quantified andpresented in Table 17. Using Eq. (11) and data from Tables 7 and 8,the amount of different types of emission that can be reducedthrough the energy savings associated with the different policymeasures/options have been estimated and presented. It has beenfound that 77,569 MWh energy and US$ 4,964,416 bills can be

Table 17Energy and bill savings for different energy savings measures.

Energy savings options Energy savings, MWh Bill savings, US$

EI reduction from 130 to 114 15,728 1,006,592

Raising thermostat set point temperature 17,477 1,118,528

Housekeeping 7665 490,560

CFL 97 6,208

Advanced glazing 18,205 1,165,120

Insulation 14,564 932,096

Standby 3833 245,312

Table 16Energy intensity for commercial building in Malaysia and other countries.

Country Energy intensity (kWh/m2) Sources

Malaysia 130 –

Thailand 154 Saidur et al. (2007)

Japan 121

Shanghai 180

Greece 187

USA 293 Lombard et al. (2008)

saved by different energy-saving options and also that hugereductions in emissions can be achieved as a result of energysavings. Yamtraipat et al. (2006) carried out some work on anindoor ac set point temperature and some experimental work onthe influence of temperature on ac energy consumption.

The authors found that raising the thermostat set point from22 to 26 1C can save 24% energy consumption, and observationsmade in Malaysia, which has a climate very like that of Thailand,turn out to be very similar. One valuable finding is that 80% of therespondents considered that 26 1C was an acceptable comfortrange.

Emission reductions, kg Estimated using references

CO2 SO2 NOx CO

51,191,871 306,434 144,361 31,136 Present author

8,746,679 52,358 24,666 5320 Yamtraipat et al. (2006)

3,836,087 183,673 10,818 2333 Uchiyama (2002)

12,147,860 581,643 34,257 7389 Author’s own calculation

9,111,020 436,238 25,693 5542 Chirarattananon and Taweeku (2003)

7,288,816 348,991 20,554 4433 Chirarattananon and Taweeku (2003)

1,918,294 91,848 5410 1167 Present author

40,000

30,000

20,000

10,000

Bill

sav

ings

1 1.5 2 3 4 5 7.5 10 15 20 30 40 75 1001250

Fig. 5. Bill savings for high-efficient motors at different loadings.

ARTICLE IN PRESS

Table 18Avoided energy and emission with VSD.

Motor power, kW Avoided energy (MWh) for

speed reduction of

Avoided emission (kg) for 20% speed

reduction

Avoided emission (kg) for 40% speed

reduction

Avoided emission (kg) for 60% speed

reduction

20% 40% 60% CO2 SO2 NOx CO CO2 SO2 NOx CO CO2 SO2 NOx CO

1 118 275 433 59,055 354 167 36 137,629 824 388 84 216,703 1297 611 132

1.5 220 513 806 110,103 659 310 67 256,740 1537 724 156 403,377 2415 1138 245

2 237 554 871 118,611 710 334 72 277,259 1660 782 169 435,908 2609 1229 265

3 276 643 1011 138,129 827 390 84 321,801 1926 907 196 505,973 3029 1427 308

4 496 1157 1818 248,232 1486 700 151 579,041 3466 1633 352 909,851 5446 2566 553

5 637 1486 2334 318,798 1908 899 194 743,695 4452 2097 452 1,168,092 6992 3294 710

7.5 1781 4156 6531 891,334 5336 2514 542 2,079,945 12,451 5865 1265 3,268,557 19,566 9217 1988

10 2633 6143 9653 1,317,732 7888 3716 801 3,074,375 18,403 8670 1870 4,831,018 28,918 13,623 2938

15 3726 8695 13,663 1,864,744 11,162 5259 1134 4,351,569 26,048 12,271 2647 6,837,894 40,932 19,283 4159

20 687 1604 2521 343,822 2058 970 209 802,751 4805 2264 488 1,261,680 7552 3558 767

30 977 2279 3581 488,957 2927 1379 297 1,140,567 6827 3216 694 1,792,176 10,728 5054 1090

40 1719 4010 6302 860,304 5150 2426 523 2,006,877 12,013 5659 1221 3,153,949 18,880 8894 1918

75 449 1048 1647 224,710 1345 634 137 524,490 3140 1479 319 824,271 4934 2324 501

100 286 668 1050 143,134 857 404 87 334,313 2001 943 203 525,491 3146 1482 320

125 163 380 597 81,576 488 230 50 190,178 1138 536 116 298,779 1788 843 182

Table 19Bill savings and payback period for VSD.

Motor power, kW Bill savings (US$) for speed reduction of Payback period (yr) for speed reduction of

10% 20% 30% 40% 50% 60% 10% 20% 30% 40% 50% 60%

1 2517 7550 12,583 17,616 23,152 27,682 5.15 15.44 25.73 36.02 47.35 56.61

1.5 4691 14,074 23,457 32,840 43,161 51,605 5.14 15.43 25.72 36.01 47.33 56.58

2 5066 15,199 25,332 35,464 46,610 55,730 5.01 15.03 25.06 35.08 46.10 55.12

3 5883 17,649 29,415 41,181 54,123 64,713 6.17 18.50 30.83 43.17 56.73 67.83

4 10,577 31,731 52,886 74,040 97,309 116,348 80.13 240.39 400.65 560.91 737.19 881.43

5 13,582 40,747 67,912 95,077 124,959 149,407 108.66 325.98 543.30 760.62 999.67 1195.26

7.5 37,998 113,993 189,988 265,983 349,578 417,973 39.83 119.49 199.15 278.81 366.43 438.13

10 56,163 168,489 280,815 393,142 516,700 617,794 425.48 1276.43 2127.39 2978.34 3914.40 4680.26

15 79,495 238,485 397,475 556,464 731,353 874,444 635.96 1907.88 3,179.80 4451.72 5850.83 6995.55

20 14,666 43,997 73,329 102,660 134,925 161,323 88.88 266.65 444.42 622.18 817.73 977.72

30 20,832 62,496 104,160 145,824 191,654 229,152 905.74 2717.22 4528.70 6340.17 8332.80 9963.13

40 36,664 109,993 183,322 256,650 337,312 403,308 3,333.12 9999.36 16,665.60 23,331.84 30,664.70 36,664.32

75 9583 28,748 47,914 67,079 88,161 105,410 416.64 1249.92 2083.20 2916.48 3833.09 4583.04

100 6111 18,332 30,554 42,775 56,219 67,218 555.52 1666.56 2777.60 3888.64 5110.78 6110.72

125 3472 10,416 17,360 24,304 31,942 38,192 694.40 2083.20 3472.00 4860.80 6388.48 7638.40

Table 20Avoided emission for using high efficient motors.

Avoided emission (kg) for 50% loading Avoided emission (kg) for 75% loading Avoided emission (kg) for 100% loading

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

27,025 162 76 16 3503 21 10 2 2502 15 7 2

33,531 201 95 20 4004 24 11 2 4504 27 13 3

25,023 150 71 15 5005 30 14 3 3003 18 8 2

46,043 276 130 28 7007 42 20 4 4504 27 13 3

44,041 264 124 27 7507 45 21 5 6506 39 18 4

68,064 407 192 41 5505 33 16 3 6006 36 17 4

81,576 488 230 50 11,511 69 32 7 15,014 90 42 9

30,4785 1824 859 185 30,529 183 86 19 20,019 120 56 12

38,7362 2319 1092 236 39,037 234 110 24 36,534 219 103 22

51,548 309 145 31 8007 48 23 5 7007 42 20 4

13,012 78 37 8 5005 30 14 3 4004 24 11 2

11,0603 662 312 67 15,515 93 44 9 16,015 96 45 10

26,525 159 75 16 2502 15 7 2 1001 6 3 1

12,011 72 34 7 1001 6 3 1 500 3 1 0

10,510 63 30 6 1001 6 3 1 500 3 1 0

R. Saidur / Energy Policy 37 (2009) 4104–4113 4111

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R. Saidur / Energy Policy 37 (2009) 4104–41134112

Chirarattananon and Taweekun (2003) reported that 25% oftotal building energy can be saved if advanced glazing is appliedto the windows of buildings and that by insulating buildings 20%of total energy can be saved. Table 17, which is based on theirfindings, estimates resultant energy savings.

Using Eqs. (11) and (12) and data shown in Tables 9–11, energysavings and bill savings as a result of using high-efficiency motorshave been estimated and presented in Figs. 4 and 5.

Using Eq. (13) and data shown in Tables 9 and 10, energysavings using VSDs have been estimated and are presented inTable 18. Using data from Tables 9 and 12 and energy savingsshown in Table 18, bill savings associated with energy savings andpayback period through using VSD have been calculated and arepresented in Table 19.

Using Eq. (14) and data shown in Tables 7 and 8, emissionreductions associated with energy savings as a result of usingVSDs have been calculated and presented in Table 18. Similarly,emission reductions associated with high-efficiency motor energysavings have been estimated and are presented in Table 20.

4. Payback period

Using Eq. (15), payback periods for using high-efficiencymotors, using VSD to save energy by matching the speed ofmotors has been estimated and presented in Fig. 6 (i.e., for high-efficiency motors) and Table 19 (i.e., for VSD).

These payback periods indicate the introduction/implementa-tion of energy-efficient motors seems very cost-effective as theirpayback periods are less than one third of the motor life (if anaverage motor life 20 yr is considered), particularly for largemotors. Tolvanen (2008a, b) reported that the very short paybackperiods for larger motors are economically very viable and this isin contrast with VSD which is not economically viable for smallermotors whose payback period is significantly longer. Abbott(2006) reported that payback period of using VSDs for differentsizes and categories of motors ranges from 0.4 to 1.5 yr.

The author also estimated the payback period for replacingincandescent bulbs with CFLs using Eq. (15) and data from Table13 and payback period found to be about 0.76 which is less thanthe four-year life of a CFL. Replacing an incandescent with a CFL iscost-effective and a good investment over the life time of a CFL,since the payback period is less than one third of life span.

Saidur (2008) reported that retrofitting walls with differenttypes and thickness of insulation is economically viable (i.e.,1–3.19 yr), since the payback period is less than one third of thelife span. As huge amounts of energy can be saved annually fromthe retrofitting of roof insulation, the payback period is very short

140.00

120.00

100.00

80.00

60.00

40.00

20.00

0.00

Payb

ack

Perio

d, Y

r

1 1.5 2 3 4 5 7.5 10 15 20 30 40 75 100125Motor Power, kW

50% Load

75% Load

100% Load

Fig. 6. Payback period for high-efficient motors at different loads.

and return on investment can be obtained within a short period oftime (i.e., payback period 0.55–3.76).

Savings for advanced glazing and figures for the paybackperiod are from Chirarattananon and Taweekun (2003), sincethere is no comparative data available in Malaysia. Chirarattana-non and Taweekun (2003) also show that the payback period foradvanced glazing is about 4.4–7.4 for government office buildings.

5. Conclusions

This paper has identified major energy-using equipment inMalaysian office buildings and compared energy usage of officebuildings’ equipment with a number of selected countries. Thepaper has also estimated and compared EI with some otherselected countries. It also has been found that huge amount ofenergy and costs (bills) can be saved and emissions can bereduced by introducing different energy savings options in thissector. Based on a literature review, it is found that the predictedenergy savings for different energy-saving strategies can beachieved within a viable payback period, though it should berecognized that this estimation has been demonstrated only for asmall number of office buildings in Malaysia. Nonetheless, thereare other commercial sub-sectors where significant savings ofenergy and cost (bills) can be made and associated emissions canbe reduced by adopting different energy-saving measures.

Among the strategies analyzed, housekeeping, raising thermo-stat set point temperatures, and standby do not require anyadditional investment to implement and can, therefore, berecommended as energy-saving strategies, as can the replacementof incandescent with CFL and the use of insulation, whosepayback period is very short compared to life span, are also foundto be economically viable.

Further, it has been shown that the use of high-efficiencymotors is economically viable if motors are operated at lowerloads (i.e., load less than 50%) and that the use of VSD iseconomically very viable for some motors with 10 and 15 kW,particularly at 60% speed reduction.

Acknowledgements

The author would like to acknowledge the help provided by theUniversity of Malaya ISI (UPISI) Journal Centre in proofing andediting the text and to thank personally Mr. Hishamuddin Ibrahim,a PTM officer who provided data to carry out this research.

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