office building jouvan chandra pratama...

Effects of Indoor Air Quality on the Occupant’s Health and Productivity in an

Office Building

JOUVAN CHANDRA PRATAMA PUTRA

A thesis submitted in

Fulfilment of the requirement for the award of the

Master Degree of Civil Engineering

Faculty of Civil and Environmental Engineering

University Tun Hussein Onn Malaysia

APRIL 2015

v

ABSTRACT

Indoor Air Quality (IAQ) is an important parameter in deciding the status of Sick

Bulding Syndrome (SBS). Poor IAQ which leads to SBS can result in adverse effect

on the health of the occupant which causing lower productivity. This study was

conducted to establish correlation between IAQ and employee’s productivity. Five

parameters of IAQ which include air velocity, air temperature, relative humidity,

particulate matters ≥ 0.3 µm and CO2 were considered in this study. The values of

these parameters were measured using Davis Anemometer, Particle Counter GT 521

and YES Plus LGA Meter. The measured data were then used as an input data for

simulation model of the room using Comsol Multiphysics software. The simulation

generated the indoor air velocity of the room and particle distribution. For validation

purpose, only the predicted velocity was compared with the measured value, and

found that the percentage difference were in the range of 1.5% to 8.45% (below than

10%). Once the model had been validated, the parametric study of air supply inlet

position was conducted on the model and found that the position of air supply inlet

with x = 2.5 ft, y = 10 ft and H = 6.5 ft give the most efficient air distribution model

for diluting the impurities due to the particulate. The questionnaire survey distributed

amongst the occupants of the room showed that the occupants were less satisfied

(75%) with the IAQ which can lead to SBS problem. The analysis of correlation

between IAQ and occupant's productivity depicted that both of the factors were

correlated with Rank-Spearman value of 0.648. This study serves as a good platform

in assessing IAQ based on the modelling and simulation approach.

vi

ABSTRAK

Kualiti udara dalaman merupakan parameter penting dalam menentukan status

Sindrom Bangunan Sakit (SBS). IAQ yang rendah boleh memberi kesan yang buruk

pada kesihatan penghuni dan juga menyebabkan produktiviti rendah. Kajian ini

dijalankan untuk menentukan tahap SBS bilik pejabat yang dipilih dan kesannya

terhadap produktiviti penghuni. Parameter SBS yang dipertimbangkan dalam kajian

ini adalah IAQ dan tahap kepuasan penghuni. Lima parameter IAQ yang terlibat

dalam kajian ini adalah halaju udara, suhu udara, kelembapan relatif, zarah ≥ 0.3 µm

dan CO2. Nilai parameter tersebut diukur menggunakan Davis Anemometer, Particle

Counter GT521 dan YES Plus LGA Meter. Data diukur digunakan sebagai input bagi

model simulasi bilik dengan menggunakan perisian Comsol Multiphysics. Simulasi

yang dihasilkan adalah halaju udara dalaman dan pengedaran zarah. Untuk

pengesahan, hanya halaju udara sahaja divalidasikan dengan nilai yang diukur. Hasil

validasi mendapati peratus perbezaan adalah 1.5% kepada 8.45% (iaitu kurang dari

10%). Apabila model telah disahkan, kajian parametrik dijalankan ke atas model dan

mendapati bahawa kedudukan masuk dengan x = 2.5 ft, y = 10 ft dan H = 6.5 ft

memberikan model pengedaran udara yang paling berkesan untuk mencairkan

kekotoran zarah . Kaji selidik soal selidik yang diedarkan di kalangan penghuni bilik

itu mendapati bahawa penghuninya kurang berpuas hati (75%) dengan IAQ dan ini

boleh membawa kepada terjadinya SBS. Analisis korelasi antara IAQ dan

produktiviti penghuni menunjukkan bahawa kedua-dua faktor ini berkait rapat

dengan nilai Rank-Spearman 0.648. Kajian ini bertindak sebagai platform yang baik

dalam menilai IAQ berdasarkan pendekatan model.

vii

TABLE OF CONTENTS

TITLE i

DECLARATION ii

DEDICATION iii

ACKNOWLEDGEMENT iv

ABSTRACT v

ABSTRAK vi

TABLE OF CONTENTS vii

LIST OF PUBLICATIONS x

LIST OF TABLES xi

LIST OF FIGURES xii

LIST OF SYMBOLS xvi

LIST OF APPENDICES xix

CHAPTER 1: INTRODUCTION

1.1 Background 1

1.2 Problem Statement 3

1.3 Aim & Objectives 4

1.4 Significance of Research 5

1.4 Scope of The Research 5

1.5 Thesis Layout/Organization 5

CHAPTER 2: LITERATURE REVIEW

2.1 Introduction 7

2.2 Indoor Air Quality Definition 7

2.2.1 Particulate Matter (PM) 11

2.2.2 Gas Pollutants 11

2.2.3 Temperature and Humidity 14

2.2.4 Air Movement 15

2.3 Ventilation 15

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2.3.1 Mechanical Ventilation 15

2.4 Sick Building Syndrome (SBS) 18

2.5 Productivity 21

2.5.1 IAQ Affecting Productivity 21

2.6 Computer Modelling and Simulation in IAQ Study 23

2.6.1 COMSOL Multiphysics Software 26

2.7 Summary 28

CHAPTER 3: RESEARCH METHODOLOGY

3.1 Introduction 29

3.2 Research Framework 29

3.3 Data Collection 32

3.3.1 Physical Measurement 32

3.3.2 Questionnaire 38

3.3.2.1 Sick Building Symptoms 39

3.3.2.2 Measurement Scale 40

3.4 Analysis Method 40

3.4.1 Descriptive Analysis 40

3.4.2 Correlation of Rank Spearman 41

3.5 Comsol Multiphysics Modelling and Simulation 41

3.5.1 Geometry 42

3.5.2 Mesh 43

3.5.3 Solver and Computation 44

3.5.4 Post Processing Results 44

3.6 Summary 45

CHAPTER 4: FIELD STUDY OF IAQ AT ORICC BUILDING

4.1 Introduction 46

4.2 IAQ Measurement 46

4.2.1 ORICC Office Building 46

4.2.2 Equipments and Measurement 48

4.2.3 Results and Discussion 52

4.2.4 Analysis of Critical IAQ 60

4.3 Questionnaire Survey 64

4.3.1 Results and Discussion 65

ix

4.3.2 Likeliness of SBS Presence 66

4.3.3 Occupant Satisfaction 69

4.3.4 Correlation of Comfort Environmental

Parameters on Working Performance 70

4.4 Summary 71

CHAPTER 5: MODELLING OF AIRFLOW AND

PARTICLE MOVEMENT

5.1 Introduction 72

5.2 Modelling of Room 5 72

5.2.1 Construction of Space Geometry 73

5.2.2 Selection of Physics Module 75

5.2.3 Assigning Values and Defining Boundary 76

5.2.4 Meshing 79

5.2.5 Simulation of Room 5 80

5.2.6 Simulation Process 80

5.3 Validation 85

5.4 Parametric Study 86

5.5 Summary 92

CHAPTER 6: CONCLUSION AND RECOMMENDATIONS

6.1 Introduction 93

6.2 Significant Findings 93

6.2.1 Objective 1; Determine The Level of IAQ

in The Office 93

6.2.2 Objective 2; Establish the Correlation

Between IAQ and Employee's productivity 94

6.2.3 Objective 3; Determine the Best Position for

Improving IAQ 94

6.3 Limitations 94

6.4 Recommendation for Future Work 95

REFERENCES 96

APPENDIX 108

x

LIST OF PUBLICATIONS

.

Papers:

1. Ade Asmi, Jouvan Chandra Pratama Putra, Ismail bin Abdul Rahman,

(2012). ”A Study of Indoor Air Quality in University Laboratory Buildings”,

International Journal of Engineering Science and Technology (ISSN: 0975-

5462) Vol. 4 No. 09 September 2012 (indexed by Google Scholar)

2. Ade Asmi, Jouvan Chandra Pratama Putra, Ismail bin Abdul Rahman

(2012). ”A Study of Indoor Air Quality of Public Toilet in University’s

Building. In 2012 IEEE Colloqium Humanities, Science and Engineering

(CHUSER) (pp. 403-408). Ieee. doi:10.1109/CHUSER.2012.6504347

(indexed by scopus)

3. Ade Asmi, Jouvan Chandra Pratama Putra, Ismail Abdul Rahman, (2014).

”Simulation of Room Airflow Using Comsol Multiphysics Software”,

Applied Mechanics and Materials vol. 465-466 pp 571-577 (indexed by

scopus and ISI)

4. Ismail Abdul Rahman, Jouvan Chandra Pratama Putra, Ade Asmi, (2014).

”Modeling of Particle Dispersion in Mechanically Ventilated Space”, Modern

Applied Science 8(3) p.60 (indexed by scopus)

5. Ismail Abdul Rahman, Jouvan Chandra Pratama Putra, Ade Asmi, (2014).

"Assessment of Toilet's Indoor Air Quality in Relation to Asthmatic People",

Modern Applied Science. (Indexed by Scopus)

6. Ismail Abdul Rahman, Jouvan Chandra Pratama Putra, Sasitharan

Nagapan, (2014). "The Correlation of Indoor Air Quality Towards Working

Performance in University Office Building", Modern Applied Science.

(Indexed by Scopus)

7. Ismail Abdul Rahman, Jouvan Chandra Pratama Putra, Ade Asmi,

(2014). "Modelling of Particle Transmission in Laminar Flow Using Comsol

Multiphysics" (submitted to International Conference on Advance in

Manufacturing and Materials Engineering -

https://sites.google.com/site/icamme14/)

8. Ismail Abdul Rahman, Jouvan Chandra Pratama Putra, Abdul Halid,

(2015). "Airflow Behaviour in Particle Transmission in an Office Building".

(submitted to IConGDM 2015).

9. Ismail Abdul Rahman, Jouvan Chandra Pratama Putra, Sasitharan

Nagapan, Ade Asmi, (2015). "Effects of Inlet Air Supply on Particle

Deposition in an Office Building". (Submitted to IConGDM 2015).

xi

LIST OF TABLES

2.1 Summary of Reported Associations between

Work-Related Symptoms and Various Environmental Factors

and Measurement from Studies 20

2.2 Input Requirements for COMIS Simulation

of Multi-Zone Airflow 24

2.3 Researchers Involved with COMSOL Multiphysics 27

3.1 Spesification of Met-One Particle Counter GT-521 33

3.2 Spesification and Accuration of YES Plus LGA Meter 35

3.3 Spesification and Accuration of Davis Anemometer 36

3.4 Scale Used to Measure and Interprete Worker’s Perception 40

3.5 Domain Names of Geometry 43

3.6 COMSOL’s Solver Types 44

4.1 Average Values of CO2 and PM ≥ 0.3 µm for 8 Hours 64

4.2 Likeliness of SBS Presence 67

4.3 Justification of SBS Symptoms Presence 68

4.4 Comfort Environmental Parameters vs. Working Performance 70

5.1 Input Value of Laminar Flow and

Particle Tracing for Fluid Flow 77

5.2 DoF and Computational Time for Airflow Distribution 81

5.3 DoF and Computational Time for Particle Transmission 81

5.4 Outcomes for Models 1 to 6. 83

5.5 Percentage of Transmission Probability 84

5.6 Percentage Difference Values 85

5.7 Perturbation Values 87

5.8 Parametric Study Results 90

5.9 Parametric Study Inputs for Particle Trajectories 91

LIST OF FIGURES

1.1 Number of Days for Unhealthy Air Quality

Status by Stati on, Malaysia 2012 1

1.2 Average Annual Concentration of Particulate Matter

By Land Use, Malaysia 2012 2

1.3 Location of ORRIC Office with EVERGREEN

Factory in 200 m Distance 4

2.1 Air-Conditioning (Split Unit) 17

2.2 Diagram of Relationship between Work Performance & Indoor

Environment 24

2.3 Multi-Zone Method of CONTAM and COMIS 25

2.4 Zonal Models 26

3.1 Research Methodology Flowchart 31

3.2 Met One Particle Counter GT-521 33

3.3 Yes Plus LGA Meter 35

3.4 Davis Anemometer 36

3.5 Zero Count Test 37

3.6 Flow Rate Test 38

3.7 Vertex Types 42

3.8 Boundary in 2D (left) and 3D (right) 43

3.9 Domain in 2D (left) and 3D (right) 43

4.1 Layout of ORICC Office 47

4.2 The GT-521 Screen Display 48

4.3 Outdoor Air Measurement 50

4.4 Indoor Air Measurement 51

4.5 Measured Outdoor Temperature 52

4.6 Measured Outdoor Humidity 52

4.7 Measured Outdoor Air Velocity 53

13

4.8 Measured Outdoor PM ≥ 0.3 µm 53

4.9 Measured Outdoor CO2 53

4.10 Contour of Indoor Air Humidity (%) 55

4.11 Contour of Indoor Air Temperature (°C) 56

4.12 Contour of Indoor Air Velocity (m/s) 57

4.13 Contour of Indoor Air PM ≥ 0.3 µm (particles/m3) 58

4.14 Contour of Indoor CO2 (ppm) 59

4.15 Day 1 CO2 vs. Number of Occupant 60





4.20 Day 1 PM ≥ 0.3 µm vs. Number of Occupant 62





4.25 Job Category 65

4.26 The Percentage of Working period of Occupants

in The Office Building 66

4.27 Satisfaction Regarding Temperature 69

4.28 Perceived Thermal Condition 69

4.29 Satisfaction Regarding Air Velocity 69

4.30 Perceived Air Velocity Condition. 69

4.31 Ability to Adjust Temperature 70

4.32 Ability to Adjust Air Velocity 70

5.1 Room 5 73

5.2 2D Gometry Models of Room 5 and its Hallway 74

5.3 3D Geometry Models of Room 5 75

5.4 Laminar Module in COMSOL Multiphysics 76

5.5 Coupling of Particle Tracing with Laminar Flow Modules 76

5.6 Location of Air Velocity Inlet 77

14

5.7 Location of Air Velocity outlet 78

5.8 Location of Particle Release 78

5.9 Location of Particle Outlet 79

5.10 Geometry Meshed 80

5.11 Air Velocity Distribution of Model 1 82






5.17 Particle Trajectories of Model 1 83






5.23 R2 Value for Comparison between Measured Value

and Simulated Value 86

5.24 Inlet Air Supply Position with x = 2.5 ft,

y = 10 fr and H =6.5 ft 87


y = 10 fr and H =7 ft 87


y = 10 fr and H =6.5 ft 88


y = 10 fr and H =7 ft 88

5.28 Inlet Air Supply Position with x = 2.5 ft, y = 10 ft and H = 6.5 ft 88

5.29 Simulation Behaviors for Inlet Air Supply

Position with x = 2.5 ft. y = 10 ft and H = 6.5 ft 89


Position with x = 2.5 ft. y = 10 ft and H = 7 ft 89



15


Position with x = 5.5 ft. y = 10 ft and H = 7 ft 89



16

LIST OF SYMBOLS AND ABBREVIATIONS

%RH - Percentage of Relative Humidity

ρ - Air Density

A - Cross Section Area of the Opening

AO - Terrain of The Area

Al - Aluminium

ASHRAE - American Society of Heating, Refrigerating, and

Air-Conditioning for Engineer

°C - Degree Celcius

CaCO3 - Calcium Carbonate

Cd - Cadmium

CD - Coefficient of Discharge

CFM - cubic feet per minute

CH4 - Methane

CO - Carbon Monoxide

CO2 - Carbon Dioxide

COHb - CarboxyHemoglobin

Cu - Cuprum

ETS - Environmental Tobacco Smoke

Fe - Ferrum

H+ - Hydrogen

HVAC - Heating, Ventilation, and Air-Conditioning

IAP - Indoor Air Pollutants

IAQ - Indoor Air Quality

IPCC - Intergovernmental Panel on Climate Change

kg/m3 - kilogram per meter cubic

17

Mn - Mangan

NO3- - Nitrate

NH4+

- Ammonium

NaCl - Natrium Chloride

Ni - Nickel

NO - Nitrogen Oxide

NO2 - Nitrogen Dioxide

O3 - Ozone

OHb - OxyHemoglobin

Pb - Plumbum

PDE - Partial Differential Equations

PM - Particulate Matter

PM10 - Particulate Matter smaller than 10 µm in diameter

PM2.5 - Particulate Matter smaller than 2.5 µm in diameter

PM1 - Particulate Matter smaller than 1 µm in diameter

ppm - parts per million

Q - Volumetric Flow Rate

RSP - Respirable Suspended Particle

RH - Relative Humidity

Si - Silicon

SO2 - Sulphur Dioxide

SO42-

- Sulfate

SPM - Suspended Particulate Matter

SBS - Sick Building Syndrome

THI - Temperature Humidity Index

Ti - Titanium

TLV - Threshold Limit Value

UREF - Reference Wind Velocity

UMET - Wind Velocity Measured at The Weather Station Nearest to

The Building Location

U.S. EPA - United States Environmental Protection Agency

TVOC - Total Volatile Organic Compounds

U - Air Velocity Leaving the Opening

18

UTHM - University Tun Hussein Onn Malaysia

V - Vanadium

VOCs - Volatile Organic Compounds

WHO - World Health Organization

Zn - Zincum

19

LIST OF APPENDICES

APPENDIX TITLE PAGE

A IAQ in Malaysia and other countries 108

B SBS symptoms 128

C Outdoor air quality 129

D Questionnaire part 151

E Questionnaire results 159

F Re number and validation 167

1

CHAPTER 1

INTRODUCTION

1.1 Background

In Malaysia, air quality becomes an interesting issue to be investigated since the

rapid growth of industrial area which is not only contribute to the economic growth

but also at the same time is affecting air quality as in Figures 1.1 and 1.2 respectively.

Figure 1.1: Number of days for unhealthy air quality status by station, Malaysia 2012

(Department of Statistic Malaysia, 2013).

2

Figure 1.2: Average annual concentration of Particulate Matter by land use,

Malaysia 2012 (Department of Statistic Malaysia, 2013).

According to study conducted by WHO (2005), more than 2 million

premature deaths each year are attributed to the effects of urban outdoor air pollution

and indoor air pollution. For controlling indoor air quality, ventilation is a commonly

way to provide the healthy air for breathing (Zhang, 2005) by both diluting the

pollutants originating in the building and removing the pollutants from building

(Etheridge and Sandberg, 1996a; Awbi, 2003). Additionally, Sick Building

Syndrome (SBS) is one of the indicators which can be used for assessing the

capability of ventilation in providing healthy air within building (Finnegan et al.,

1984; William, 2009; Guo et al., 2013; Norhidayah et al., 2013).

According to Israeli and Pardo (2011), SBS is defined as a term coined for a

set of several clinically recognizable symptoms and ailments without a clear cause

reported by occupants of a building. The symptoms usually resolve soon after

occupants leaving the building (Environmental Protection Agency, 1991; Norhidayah

et al., 2013). In addition, these symptoms can reduce working performance of

employee’s due to sick leave and it must be noted that SBS is not only a health

hazard for employees but it is an adverse impact to the company. Thus, these

motivates to study on the effect of indoor air quality on the occupant's health and

productivity in an office building.

3

1.2 Problem Statement

In Malaysia, research that related with indoor air quality in work place is restrictive

as compared to other country (Mahbob et al., 2011) and people mostly spend 90% of

their times at indoor for working, living, etc (Frontczak and Wargocki, 2011).

According to U.S. EPA (2000), pollutants on indoor air are two to five times and

occasionally more than 100 times higher than outdoor air. In order to overcome that

problem, mechanical ventilation system is one of ventilation types widely used in

indoor space like office building. However, the utilization of mechanical ventilation

could be also responsible with the problems regarding with IAQ like high level of air

contaminants due to the insufficient of airflow (Anderson, 1998) cited by Posner and

Buchanan (2003) that will lead to SBS (Dutton et al., 2013). Thus, the risks to health

which will lead to the decrease of employee productivity through exposure to indoor

air pollution maybe greater than those posed by outdoor air pollution. Clearly, the

quality of indoor air should be as high as possible. Since Universiti Tun Hussein Onn

Malaysia (UTHM) located near to the factories that emit pollutants, it is interesting

to know the effects of outdoor air quality towards the indoor air quality. Thus, this

study investigates an indoor air quality of The Office of Research, Innovation,

Commercialisation, and Consultancy (ORICC) rooms in UTHM. Besides that, it also

simulates the performance of ventilation system in controlling the indoor air quality.

Finally, this study correlates the indoor air quality of the rooms with employees’

productivity.

4

Figure 1.3: Location of ORRIC office with Evergreen factory in 200 m distance.

1.3 Aim and Objectives

The primary purpose of this research is to study the effects of IAQ on the occupant’s

health and working performance. This aim can be achieved by carrying-out the

following objectives as below:

i. To determine the level of IAQ parameters in the selected rooms.

ii. To establish correlation between IAQ and working performance.

iii. To determine the optimum position of inlet air supply for improving IAQ.

The determination of IAQs’ level is to check whether its level exceed the

Threshold Limit Value (TLV). Then, the correlation between IAQ and working

performance is established to assess their relationship. Finally, the determination of

optimum position of inlet air supply for improving IAQ is carried out by perturbing

its location as a strategy to enhance the working performance of occupants.

5

1.4 Significance of Research

The significances of this research include :

i. The outcomes of this research as an input to the authority in improving the

quality of IAQ of the office building in ensuring the heatlh of occupant.

ii. An alternative approach to improve IAQ in a particular room is generated in

this research by optimizing the location of inlet air supply in order to dilute

the pollutants.

1.5 Scope of the Research

This study was conducted on ORICC office at ground floor. The office is located in

UTHM area and has a total area about 244.238 m2. However, for simulation works it

involves only one (1) of the selected room which is the most critical in terms of

measured IAQ. The selected rooms are ventilated by air-conditioning systems (split

unit). Employee’s productivity is measured based on the questionnaire survey on the

occupants of the rooms. For IAQ, the parameters measured are confined to air

velocity, number of particles (PM ≥ 0.3 µm), CO2, temperature and humidity.

1.6 Thesis Layout/Organization

The organization of this thesis consists of 6 chapters and divided as followings :

Chapter 1: this chapter discusses on the fundamental and basic framework for

this thesis. It contains background of the study, problem statement, aim and

objectives, significance of research and scope of the research.

Chapter 2: this chapter discusses the literature review of published research

work on Indoor Air Quality (IAQ) and types of ventilation both experimentally and

modelling. Besides, the adverse effect which occurs regarding with poor IAQ such as

Sick Building Syndrome that will decrease productivity of occupant’s also described.

6

At the last an introductory review of the latest available modelling tools are

presented here, which can simulate the IAQ in ventilated room.

Chapter 3: presents the framework idea of this whole research, how the

research designed and the methodology used. This chapter is also contains detailed of

research procedures and the selected analysis method.

Chapter 4: reports how the measurement was conducted, which contains of

analysis of IAQ measurement while questionnaire survey was conducted based on

occupant’s perception .

Chapter 5: this chapter presents the modelling and simulation of IAQ in the

selected rooms using COMSOL Multiphysics.

Chapter 6: this chapter discusses the conclusion achieved from this study by

keeping in view the core principles, and objectives of this study. Then, the

recommendations for future study are highlighted.

7

CHAPTER 2

LITERATURE REVIEW

2.1 Introduction

The literature pertaining to IAQ and its effect to health, working performance, as

well as modelling and simulation of IAQ were reviewed in this chapter. It helps to

point out some useful information regarding the research topic which is to study IAQ

and its effects to occupant’s health and working performance.

2.2 Indoor Air Quality (IAQ) Definition

Indoor Air Quality (IAQ) firstly investigated in 1970s (Zhang, 2005) and continues

until these days because it is a basis determinant of healthy life and people’s well

being, comfort and productivity (Norhidayah et al., 2013). In defining IAQ, Bluyssen

(2009) describes it within two (2) points of view. From the human point of view IAQ

of a space is the physical effect of exposures of people to indoor air of the space they

are visiting or occupying, as experienced by those people. IAQ at certain point in

time can for example be expressed in an odorous unit, while IAQ over time can for

example be related to the number of people developing certain illness. From the

indoor air point of view, IAQ is often expressed in a certain ventilation rate (in L/s

per person and/or L/s per m2 floor area) or in concentrations for specific compounds.

These concentrations are influenced by the source present in indoor or outside the

space (outdoor sources and sources present in HVAC system or surrounding spaces).

Additionally, Muhamad-darus et al. (2011) defined indoor air quality as a term

8

referring to the air quality within and around buildings, especially being its relation

to health and productivity of its occupant.

To identify IAQ parameters, a number of studies regarding IAQ and its

adverse effect on health which occurs from poor IAQ are tabulated in APPENDIX A

and disscused as follows:

Aizat et al. (2009) studied regarding IAQ & SBS in Malaysia buildings to

investigate the association between SBS and indoor air pollutants in two differents

buildings (new & old). The IAQ parameters considered are Relative Humidity (RH),

temperature, Carbon Dioxide (CO2), Carbon Monoxide (CO), ventilation rate, TVOC,

Particulate Matter (PM) and air velocity. The findings from their study indicated that

the CO2 concentration on certain level was major factor contribute to SBS complain

among office workers. Subsequently, Norhidayah et al. (2013) studied IAQ & SBS

in three selected buildings in Malaysia to determine the association between IAQ

parameters and SBS symptoms. The IAQ parameters considered are air velocity,

temperature, RH, CO2, CO, fungi, and PM. The findings suggested that the important

predictor of SBS are ventilation and accumulation of possible contaminants within

the indoor environment.

Furthermore, Sulaiman and Mohamed (2011) investigated the association

between SBS and indoor air pollutants through questionnaire which refer to the

Malaysia Industry Code of Practice on Indoor Air Quality 2010 (MCPIAQ). The

several IAQ parameters such as Volatile Organic Compounds (VOC), CO, CO2, RH,

temperature, formal dehyde, total bacteria counts and total fungal counts were used

in this study. The findings indicated that CO2 has strong correlation with other indoor

pollutants that cause SBS symptoms. However, it was also indicated that temperature,

TVOC, humidity and bacteria are important indoor air factors that can influence the

prevalence of SBS. On other hand, Fadilah and Juliana (2012) not only investigated

the association between IAQ and indoor air pollutants but also its effect to SBS

symptoms. The parameters considered are temperature, RH, air velocity, air flow,

ventilation rate, CO2 and PM. The findings suggested that ventilation is necessary to

be maintained in terms of its capability to dilute indoor air pollutants especially PM.

From the discussion above, the IAQ parameters which commonly used are

temperature, relative humidity, air velocity, Particulate Matter (PM) and Carbon

Dioxide (CO2). Subsequently, the several of adverse effects will be occur as a

9

consequence for poor IAQ such as Sick Building Syndrome (SBS), occupant

dissatisfaction and decrement of employee productivity. According to the findings

from Aizat et al. (2009), in order to decrease the SBS it can be achieved either by

increasing the ventilation rate or through source control of pollutants in which point

sources of contaminants can be identified and it is more cost effective. The

occurrence of SBS is not caused directly by CO2 and Ultra-Fine Particle (UFP)

exposure, but it caused by the exposure between CO2, UFP and other indoor

pollutant that may be cause SBS symptoms (Aizat et al., 2009).

In addition, to compare the IAQ parameters between Malaysia and other countries, a

number of IAQ parameters from other researches regarding IAQ in overseas are

tabulated in APPENDIX A and discussed as follows:

Yua et al. (2009), studied air-conditioning system and IAQ control for human health

by reviewing some control methods of IAQ at past few years. The parameters

considered are temperature, RH, air exchange rate, air movement, ventilation,

particle pollutants, biological pollutants and gaseous pollutants. They concluded that

the composition of indoor pollutant is quite complex and their concentrations are

greatly different. The chemical reaction among indoor pollutants may occur, which

can produce more irritating secondary pollutants. Only if these problems are solved,

then indoor air can be controlled accurately. Subsequently, Rios et al. (2009)

investigated the association between work-related symptoms and IAQ based on

following parameters: temperature, RH, odours, PM, bioaerosol and VOC

contamination. This study found that other disregarded factors, like undetect VOCs,

mites, molds and endotoxin concentrations, may be associated to the greater

prevalence of symptoms in the sealed building. Thus, the further studies still

necessary to go deeper in this issue to enlighten the relation between IAQ buildings

and SBS symptoms. Beside that, Seppanen and Fisk (2002) investigated the

association between ventilation system and SBS symptoms. It indicated that air

conditioning, with or without humidification was consistently associated with a

statistically significant increase in the prevalence of one or more SBS symptoms.

Prevalences were typically higher by approximately 30% to 200% in air conditioned

buildings. Subsequently, Lin et al. (2005) employed numerical simulation approach

to investigate and compare the performance of displacement and mixing ventilation

under different boundary conditions. The IAQ parameters are CO, mean age of air,

10

TVOC, toluene, benzene, formaldehyde. The findings indicated that displacement

ventilation provides more better IAQ in terms of dillute CO.

Moreover, Buggenhout (2005) developed and validated an airflow pattern sensor to

determine the airflow for dilutes the indoor pollutants. This concept offers a new

approach for control the fresh air distribution on ventilated space. The method of this

approach is by using its temperature sensor to detect the jet air trajectory, and it is a

low cost and reliable method which can be easily implemented in the hardware of

existing ventilation equipment and consequently microclimate control. Besides, to

effectively design fresh airflow rate for improving IAQ, Mui and Chan (2006)

proposed Demmand Control Ventilation (DCV) which focusses on the number of

people instead of CO2 concentration level indoor to provide fresh air. However, this

is can lead to the adverse effect of occupant’s health if the level of CO2 exceed the

TLV. Hence, there is a need further research to improve it.

However, in investigating IAQ some researchers found a number of limitations as

attached in APPENDIX A namely: the discrepancy between the results of IAQ

physical measurement and the IAQ as experienced by occupant (Bluyssen, 2009;

Yua et al., 2009; Frontczak and Wargocki, 2011; Kamaruzzaman et al., 2011). For

example when the measurement results show the acceptable condition of IAQ

measured as compared to standard, the building’s occupants are still unacceptable,

and even unhealthy that leads to comfort problem. This problem may be due to the

standard established is only to regulate for the industrial environment (Rios et al.,

2009). The standard which commonly used such as NIOSH and ASHRAE are

guideline mainly developed on the basis of empirical research and laboratory studies,

which have not sufficiently dealt with the rapidly changing work environment (Choi

et al., 2012) and every single IAQ parameter may lead to the different subjective

responses (Frontczak and Wargocki, 2011). Additionaly, indoor environment study is

expensive due to its time consuming and requires the presence of several researchers

or research assistants in the surveyed building during the study period (Hummelgaard

et al., 2007). Thus, these limitations are considered to be constraint factors in the

IAQ investigation.

11

2.2.1 Particulate Matter (PM)

In the last decade, a number of epidemiological studies have clearly indicated that

urban air pollution not only can adversely impact to human health (Brunekreef and

Holgate, 2002) but also socioeconomic impact (Hays et al, 1995). Subsequently,

ambient Particulate Matter (PM) either characterized as coarse particle for the

diameter of particles less than 10 µm (PM10) or fine particle for the diameter of

particles less than 2.5 µm (PM2.5) (Fierro, 2001; Zhang, 2005; Hanapi and Din,

2012) are considered as the main cause (Karakatsani et al., 2012). The comparisons

of these two particles are attached in APPENDIX A.

According to Fierro (2001), PM is a complex mixture of extremely small

solids and liquid droplets. It is made up of a number of components, including acids

(such as nitrates and sulphates), organic chemicals, metals and soil or dust particles.

Identification of sources of particulate contaminants in an indoor environment is

important for implementation of appropriate air quality control strategies (Zhang,

2005; Massey et al., 2012). According to Yua et al. (2009), indoor particle pollutant

sources can be divided into indoor pollution sources and outdoor pollution sources.

Outdoor particles penetrate into indoor air environment through the aperture of doors

and windows, and the fresh air of air-conditioning system.

2.2.2 Gas Pollutants

Gases are identified as having potentially significant effects on humans or our

environment, and there are six gases which are affect the source of indoor pollutant

such as : Carbon Monoxide (CO), Carbon Dioxide (CO2), Nitrogen Oxide (NO),

Nitrogen Dioxide (NO2), Sulfur Dioxide (SO2), and Methane (CH4) (Hays et

al.,1995).

Carbon Monoxide (CO), is a colourless, odourless, and tasteless gas which

is produced from the incomplete combustion of any carbon-containing fuel (Hays et

al., 1995). Normally, oxygen is carried to the body’s tissues by hemoglobin in the

form of OxyHemoglobin (OHb). When CO is present, it also combines with

hemoglobin to form CarboxyHemoglobin (COHb). In fact, CO is about 200 times as

effective as oxygen (O2) in combining with hemoglobin. This means that when both

12

O2 and CO are present, hemoglobin will not be available to carry O2 to the tissues.

However, Yau et al. (2012) found that indoor CO concentrations were lower than

those of outdoors.

Carbon Dioxide (CO2), according to Hays et al. (1995), CO2 is a colourless,

odourless gas and categorized as simple asphyxiant gas. The use of Carbon Dioxide

(CO2) as an indicator of IAQ and as a tracer gas to estimate air exchange rates in

buildings are widely applied by many researchers nowadays (Gupta et al., 2007;

Mahyuddin & Awbi, 2010) and it also varied linearly with Sick Building Syndrome

symptoms (Gupta et al., 2007). The benefit from using CO2 as a tracer gas is due to

its low cost and safety consideration.

In office, the primary source of CO2 is respiration from the building’s

occupants (Apte et al., 2000; Erdman et al., 2002) and its concentrations are in range

of 350 to 2,500 ppm (Seppanen et al., 1999). The common recent standards

(ASHRAE, 1999, 2001, 2004) recommend that the difference between indoor-

outdoor of CO2 should not exceed 700 ppm. However, in Malaysia the Threshold

Limit Value for CO2 during 8 hours is 1000 ppm (DOSH Malaysia, 2010)

Nitric Oxide (NO), there are many chemical species of the oxides of nitrogen

(NOx), but nitrogen dioxide (NO2) and nitric oxide (NO) are of greatest concern as

indoor air contaminants (Hays et al., 1995). However, its database of toxicological

and health effects is somewhat limited.

Nitrogen Dioxide (NO2), is a deep lung irritant which has been shown to

result in biochemical alterations and histologically demonstrable lung damage (Hays

et al.,1995). Subsequently, in human, 80 to 90 percent of NO2 can be absorbed upon

inhalation.

The major of outdoor sources of NO2 concentrations are mobile and

stationary combustion sources (U. S. EPA, 2000), whereas indoor source include gas

cookers, wood stoves, fireplaces, and environmental tobacco smoke (ETS). NO2 is

formed from the combination of Nitrogen (N) and Oxigen (O2) during high

temperature combustion processes (Brunekreef et al., 2002) and it also often found at

higher concentrations indoors than outdoors (Lee, et al., 2002). In some indoor

environments such as industrial workplaces and home with gas stoves, peak

concentrations may reach 1 to 2 ppm with 24 hours averages of NO2 concentration

up to 0.5 ppm (Chenn and Chang, 2012). Additionally, NO2 is an irritant gas and can

13

increase susceptibility to airway infections and impair lung function in exposed

populations (Curtis et al., 2006).

Sulfur Dioxide (SO2) is a colourless gas with a strong pungent odour and the

odour can be detected at about 0.5 ppm (Hays et al.,1995). Although exposure to SO2

has not been shown to cause cancer in humans, there are serious health problems

related to exposure time both both in long term and short term (U. S. EPA, 2000).

Generally, exposures to SO2 cause a burning sensation in the nose and throat.

Subsequently, SO2 exposure can cause difficulty breathing, including changes in the

body’s ability to take a breath or breathe deeply, or take in as much air per breath.

Short term exposure to high enough levels of SO2 can be life threatening and long

term exposure to SO2 can cause changes in lung function and aggravate existing

heart disease.

Methane (CH4) is a colourless, tasteless gas that is the primary component of

natural gas (Lee et al., 2002). CH4 is produced naturally by volcanoes, ruminant

animals such as cattle and sheep, decaying plants, extraction of natural gas, coal

mining, waste disposal and also a major greenhouse gas that results from such human

activities (Lee et al., 2002). The Intergovernmental Panel on Climate Change (IPCC)

reports wide ranges in the anthropogenic CH4 emissions that are partly due to urban

areas (IPCC, 2006), while 15% to 40% of them has been estimated to derive from

gas and oil production, industry sector, landfills, and waste treatment (Denman et al.,

2007). In industry, methane is used to refine petrochemicals and in power stations to

drive turbines to create electricity (Lee et al., 2002). Generally, public may be

exposed to very low levels when breathing in air. Occupational exposure to methane

may occur in the workplace where it is extracted, produced or used. If exposed to

CH4, the potential adverse health effect that may occur depend on the way people are

exposed and the amount to which they are exposed. High levels of CH4 can displace

oxygen in the air and cause oxygen deprivation, which can lead to suffocation.

Breathing high levels of the gas can also lead to agitation, slurred speech, nausea,

vomiting, facial flushing and headache. In severe cases, breathing and heart

complications, coma and death may occur. Skin contact with liquefied gas may cause

frostbite (Lee et al., 2002).

14

2.2.3 Temperature and Humidity

Indoor temperature is considered as indoor environment factors that affect to comfort

and health of human and it becomes the most attention for common people (Huang et

al., 2012). According to The Government of The Hongkong Special Administrative

Region Indoor Air Quality Management Group (2003), indoor temperature is

influenced by factors such as the temperature control of air-conditioning, solar heat

gain, and other indoor heat sources such as lighting, electrical equipment, computers

and water heaters and humidity. Consideration should also be given to variations in

temperature within rooms served by a single thermostat. Temperature between rooms

or locations within a room may vary due to large window areas or large vertical

surfaces. Besides, a comfort of indoor temperature will be gained in the range

temperature of 20°C to 26°C (DOSH Malaysia, 2010). However, according to

(Rahman and Kannan, 1996; Yau et al., 2011) temperature standard in Malaysia is in

the range of 29 ºC - 34ºC.

As a parameter related with temperature, humidity influences thermal

comfort by affecting the human body’s ability to lose body heat through perspiration.

In humid conditions it is more difficult to lose heat – the effect is therefore the same

as raising the temperature and people feel “sticky”. High humidity also encourages

the growth of mildew and other fungi on building fabric and furnishings. Low

relative humidity causes eyes, noses and throats to dry which may lead to discomfort,

irritation and increased susceptibility to infection. Extremely low humidity can cause

static electricity which is uncomfortable for occupants and can affect the operation of

computers. The recommended indoor relative humidity is in the range of 30% to 60%

(DOSH Malaysia, 2010). Nonetheless, in Malaysia the humidity is in the range of 70%

to 90% (Rahman and Kannan, 1996; Yau et al., 2011).

15

2.2.4 Air movement

A certain amount of air movement around the human body is essential for thermal

comfort and also important in dispersing air pollutants. The required level of airflow

depends on the air temperature and humidity. In the hot and humid summer months,

for example, greater air movement can help produce a more comfortable

environment.

Airflow is determined by ventilation and convection currents which is

affected by hot air rising and cool air failing in a room (The Government of The

Hongkong Special Administrative Region Indoor Air Quality Management Group,

2003). Blocked or unbalanced ventilation systems, or too low pressure levels in

ventilation ducts may restricts air movement, producing a “stuffy” atmosphere which

makes occupants feel uncomfortable.

2.3 Ventilation

Basically, ventilation is employed for supplying fresh air into room or building and

distributes it (WHO, 2009) for providing healthy air to indoor occupants (Etheridge

and Sandberg, 1996a; Awbi, 2003). There are three basic parameters of building

ventilation for assessing the ventilation performance such as: ventilation rate, airflow

direction, and air distribution or airflow pattern. Each of those categories is depended

with the types of ventilation which can be broadly categorized into natural

ventilation and mechanical ventilation. However, since the ORICC office uses

mechanical ventilation, the following sub only focusses on mechanical ventilation.

2.3.1 Mechanical Ventilation

Mechanical ventilation supplying air into room or building by using mechanical fans

(WHO, 2009). Air-Conditioning is one of mechanical ventilation systems widely

used in the world (Yua et al., 2009). If mechanical ventilation is well designed,

16

installed and maintained there are some advantages as compared to natural

ventilation are as follows: (Awbi, 2003)

1. Mechanical ventilation systems are considered to be reliable in delivering the

designed flow rate, regardless of the impacts of variable wind and ambient

temperature. As mechanical ventilation can be integrated easily into air-

conditioning, the indoor air temperature and humidity can also be controlled.

2. Filtration system can be installed in mechanical ventilation so that harmful

microorganisms, particulates, gases, odours and vapours can be removed.

3. The airflow path in mechanical ventilation systems can be controlled, for

instance allowing the air to flow from areas where there is a source (e.g.

patient with an airborne infection), towards the areas free of susceptible

individuals.

4. Mechanical ventilation can work everywhere when electricity is available.

However, there’re also several drawbacks from usage of mechanical

ventilation: (WHO, 2009).

1. Mechanical ventilation systems often do not work as expected, and normal

operation may be interrupted for numerous reasons, including equipment

failure, utility service interruption, poor design, poor maintenance or

incorrect management (Dragan, 2000). If the system services a critical

facility, and there is a need for continuous operation, all the equipment may

have to be backed up which can be expensive and unsustainable.

2. Installation and particularly maintenance cost for the operation of a

mechanical ventilation system may be very high. If mechanical ventilation

system cannot be properly installed or maintained due to shortage of funds,

its performance will be compromised.

SPLIT UNIT

According to Sekhar (2004) and Hussin et al. (2014), a split unit system of air-

conditioning widely contributes to the high concentration level of CO2 as compared

to centralized air-conditioning system. This is probably due to its performance which

17

is inadequate to distribute air (Kumlutaş et al., 2013) and the filter of the air-

conditioner that had not work properly (Yousef et al., 2013). Subsequently, the Air-

Conditioning split unit is depicted in Figure 2.1.

Figure 2.1: Air-Conditioning - Split Unit (Owners Manual AC, 2008)

18

2.4 Sick Building Syndrome (SBS)

According to (Berardil et al., 1991), SBS has become an issue in Malaysia due to the

construction of buildings designed to be energy-efficient with air-conditioning

system, yet poor maintenance and services of Heating, Ventilation and Air-

Conditioning (HVAC) system resulting the increasing of indoor air pollutant.

From researcher’s point of view, SBS is defined as situation in which

building’s occupants experience acute health-or comfort-related effects that seem to

be linked directly to the time spent in the building (Joshi, 2008), without a clear

cause reported by building’s occupants (Israeli and Pardo, 2011). Additionally,

Burroughs and Hansen (1991), mentioned the number in percentage to determine

whether a building had experienced of SBS, in which at least 20 percent of the

building’s occupants display symptoms of illness more than 2 weeks, and the source

of these illnesses cannot be positively identified. One of the reasons that SBS is so

difficult to be investigated is that the symptoms can relatively resulted from a variety

of causes (Milica and Jasminka, 2009). According to Godish (1995), building

occupants that experienced with SBS symptoms frequently complain about the

following:

Nose and throat: dryness, stuffiness, irritation of the mucous membrane,

runny nose, sneezing, odour, taste sensations.

Eyes: dryness, itching, irritation, watery eyes.

Skin: dryness and irritation, rash, itching, eczema, erythematic, localized

swelling.

General: tight-chest, abnormal fatigue, malaise, headache, feeling heavy-

headed, lethargy, sluggishness, dizziness, nausea.

Additionally, the World Health Organization (1983) recognized sick building

syndrome to exist in all types of non-occupational buildings and non-industrial

occupational buildings. Those symptoms are identified as follows:

i. Eye, nose and throat irritation.

ii. Sensation of dry mucous membranes and skin.

iii. Erythema.

iv. Mental fatigue.

19

v. Headaches, high frecuency of airway infections and cough.

vi. Hoarseness, wheezing, itching, and unspesific hypersensitivity.

vii. Nausea & dizziness.

Furthermore, a number of extensive studies had been conducted to determine

the IAQ parameters that are triggering to the occurrence of SBS by various

researchers as attached in APPENDIX A.

Factors Associated with Sick Building Syndrome

On the risk factors associated with sick building syndrome, Hedge et al. (1992)

suggested a multiple risk model that consist of several groups of risk factors interact

with each other, impose a total stress load on building occupants and mediate

complaints of sick symptoms. The risk factors include:

i. Direct environment risk (e.g. exposure to pollutants).

ii. Indirect environmental risks (e.g. workers satisfaction with thermal

conditions).

iii. Occupational risk (e.g. job stress).

iv. Individual risks (e.g. gender, age, personality).

Lahtinen et al. (1998), suggested that sick building syndrome most likely is

multi-factorial origin related to chemical, physical, biological and psychosocial

factors that interact or coincide with one another. Psychosocial factors may serve as

moderators or mediators in the process, either increasing or decreasing the

vulnerability of the individual to environmental exposures, or as outcomes in a

situation where the subject is compelled to work in a contaminated environment.

On the environmental factors that are related to symptom prevalence,

Mendell (1993) reviewed the findings of 32 studies of 37 factors that are potentially

related to office worker symptoms and found that air-conditioning, carpets, more

workers in a space, and a ventilation rate at or below 10 liters per second per person

are generally consistently found among SBS studies to have an association of

increased symptoms. For job and personal factors, job stress or dissatisfaction,

female gender and allergies or asthma are consistently found to have an association

of increased sick symptoms. Consistent or mostly consistent findings of no

association with altered symptom prevalence were reported for total viable fungi,

20

total viable bacteria, total particles, air velocity, carbon monoxide, formaldehyde and

noise. Mendel (1993), reported that for some of the factors the findings were too

inconsistent or sparse for simple interpretation. These factors are listed in Table 2.1.

Table 2.1: Summary of reported associations between work-related symptoms and

various environmental factors and measurements from studies.

No Environmental measures Association with sick building syndrome symptoms

1.

2.

3.

4.

5.

6.

7.

8.

9.

10.

11.

12.

13.

14.

15.

16.

17.

Low ventilation rate

Carbon monoxide

Total VOCs

Formaldehyde

Total particles

Respirable particles

Floor dust

Total viable bacteria

Total viable fungi

Endotoxin

Beta-1,3-glucan

Low negative ions

High temperature

Low humidity

Air velocity

Light intensity or glare

Noise

Mostly consistent higher symptom reports

Lack of association

Inconsistent findings

Lack of association

Lack of association

Consistent findings


Lack of association

Lack of association





Consistent findings


Lack of association

No. Building factors Association with sick building syndrome symptoms

1.

2.

3.

4.

5.

Air-conditioning

Humidification

Mechanical ventilation without air

conditioning

Newer building

Poor ventilation maintenance

Consistent higher symptom report





No. Workspace factors Association with sick building syndrome symptoms

1.

2.

3.

4.

5.

6.

7.

Ionization

Improved office cleaning

Carpets

Fleecy materials / open shelves

Photocopier in room or near

Environmental tobacco smoke

More workers in the space

Lack of association

Lack of association






No. Job and personal factors Association with sick buildings syndrome symptoms

1.

2.

3.

4.

5.

6.

7.

Clerical job

Carbonless copy use

Photocopier use

Job stress / dissatisfaction

Female gender

Smoker

Allergies / asthma




Consistent higher symptom reports



Consistent higher symptom reports

From Table 2.1. it can be observed that a number of possible causes of sick

buildings syndrome were suggested in the literature, but many of them were so

inconsistent among various studies, such that the causes for SBS were still not

21

clearly established, and no conclusion can be drawn on any definite correlation of the

symptoms and the potential causative factors.

The symptoms of SBS are difficult to be diagnosed as they are dominated by

sensory reactions about which very little is known even from the medical point of

view. However, a number of SBS symptoms commonly used from many researchers

are tabulated as in APPENDIX A.

2.5 Productivity

Indoor environmental conditions may directly influence to the performance of

physical and mental work, without affecting health symptoms (Fisk, 2011).

Improving the work environment including IAQ is an effective strategy to improve

productivity of building’s occupants (Clements and Baizhan, 2000; Mahbob et al.,

2011). According to Rogers (1998), productivity is defined as the ratio of output to

input for a specific production situation. Meanwhile, Pritchard (1995) defined

productivity in three categories. The first is from the economist or engineer definition,

where the productivity is an efficiency measure: the ratio of outputs over inputs,

where both usually are expressed in dollar terms. The second definition of

productivity is a combination if efficiency (outputs/inputs) and effectiveness (output

goals). The third definition of productivity is the broadest and considers productivity

as anything that makes the organization function better. In this definition,

productivity would include efficiency and effectiveness, but also things like

absenteeism, turnover, morale, innovation, etc.

2.5.1 IAQ Affecting Productivity

According to Wyon (2004), the first of experiments series was carried out in 1999 by

researchers at The International Centre for Indoor Environment and Energy (ICIEE)

at the Technical University of Denmark (DTU). It indicated that indoor pollution

may cause a reduction in the performance of office tasks and thus revealing a new

mechanism by which indoor air pollution may reduce productivity. Based on

Antikainen et al. (2008), indoor air can affect productivity through many different

routes due to several indoor elements in office (physical, chemical, and biological)

22

that may cause health effect (respiratory, skin, nausea, nasal) among building

occupants, and lead to the decrement of occupant’s motivation.

A numerous extensively studies from various researchers regarding the effect

of IAQ towards productivity has been summarized in APPENDIX A. To investigate

the effect of IAQ on productivity, most of researchers used several types of

circumstances which are laboratory experiments (Wargocki and Wyon, 2000;

Kosonen and Tan, 2004), real study during office hour (Khalil & Husin, 2000;

Federspiel et al., 2002; Fisk et al., 2002; Kamaruzzaman and Sabrani, 2011;

Mahbob et al., 2011) and both of those two circumstances (Wyon, 2004; Antikainen

et al., 2008). The results indicated that the combination study between real study and

laboratory study are the proper approaches since the study from real study could be

validated in laboratory experiments for determine the affecting factors. Subsequently,

the IAQ parameters that affect the occupant’s productivity are temperature, relative

humidity, pollution load (CO2), CO, Particulate Matter (PM), air velocity, ventilation

rate, Ozone (O3), SO2, Formaldehyde and Radon. However, occupant’s productivity

can be assessed through its working performance, which requires concentration, such

as text typing, proof reading, etc (Wargocki & Wyon, 2000; Federspiel et al., 2002;

Kosonen & Tan, 2004; Wyon, 2004; Antikainen et al., 2008; Mahbob et al., 2011).

According to Rotundo (2002), working performance was defined as actions

that contribute to organizational goals and that are under the individual’s

performance. Subsequently, Mahbob et al. (2011) concluded the relationship of work

performance or well known as productivity with indoor environment as depicted in

Figure 2.2.

23

Work Performance

2.6 Computer Modelling and Simulation in IAQ Study

The study of IAQ through modelling and simulation has attracted various number of

researchers. Those researchers also used a various types of modelling and simulation

softwares as follows: Glantz and Rishel (2007), CONTAM is used for study the IAQ

impact associated with ventilation in large mechanically-ventilated buildings.

Additionally, this software is a multi-zone indoor air quality and ventilation analysis

computer program designed to determine the followings: (Walton and Dols, 2013)

Airflows & pressures (infiltration, exfiltration, and room-to-room airflows in

building system driven by mechanical means, wind pressure acting on the

I

M

P

A

C

T

Nature of work

Psychosocial

Environment IEQ

Space Management

Physical Health Psychological

Satisfaction & Comfortable

Output/Productivity

Figure 2.2: Diagram of relationship between work performance

and indoor environment (Mahbob et al., 2011)

24

exterior of the building, and buoyancy effects induced by the indoor and outdoor

air temperature difference.

Contaminants concentrations: the dispersal of airborne contaminants transported

by these airflows; transformed by a variety of processes including chemical an

radio-chemical transformation, adsorption and desorption to building materials,

filtration, and deposition to building surfaces, etc; and generated by a variety of

source mechanisms.

Personal exposure: The predictions of exposure of building occupants to

airborne contaminants for eventual risk assessment.

The other software for IAQ modelling and simulation is COMIS (Huang, et

al., 1999). This software is a network-based multi-zone airflow model developed by

a multinational team in the framework of International Energy Agency’s Annex 23

for simulating airflows through the building fabric due to infiltration or natural

ventilation and from zone to zone, as well as the interactions of the HVAC system,

ducts, and exhaust hoods and fans. To simulate multi-zone airflow, COMIS requires

the following inputs as highlighted in Table 2.2.

Table 2.2: Input requirements for COMIS simulation of multi-zone airflow

(Huang et al., 1999)

Crack

airflow

element

Window or door

airflow element Zone Link

Facade

element

Pressure

Coefficie

nt (Cp)

Meteorologic

al Data

Flow

coefficient

(Cs)

Flow

expo-nent

(n)

Flow coefficient

for closed

windows

Flow exponent (n)

Type of large

vertical opening

Width

Height

Schedule for

window/door

opening and

closing

Reference

Height

Volume

Temperatu

re*

Humidity*

Element

name

Zone from-

to

Height

from-to

Element

number

Relative

horizont

al

position

Relative

vertical

position

Facade

element

number

Cp value

by wind

direction

Temperature*

Humidity*

Wind speed*

Wind

direction*

Barometric

pressure*

96

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