THE ROOF TECHNOLOGIES AT LOW COST HOUSES AND THE EFFECT ON THERMAL PERFORMANCE : MATERIALS

ZULHATTA BIN MARZOKI

This project is submitted in partial fulfillment of The requirements for the degree of Bachelor of Engineering with Honours

(Civil Engineering)

Faculty of Engineering UNIVERSITI MALAYSIA SARAWAK

2004

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To all my family members

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ACKNOWLEDGEMENT

Thanks to Allah The Almighty. Finally, I have been able to complete my final year

project. Firstly, I would like to express my gratitude and appreciation to my supervisor

Dr. Azhaili Baharun who gave comments and advices on various draft of the report. His

expertise also had guided me to the end of the project.

There were a lot of other people involved due to completion of this project. Therefore, I

would like to take this opportunity to give a hearty thanks to some of those people who

helped and supported me to finish this project.

Finally, special thanks to all my family members for their encouragement and spiritual

support through out my studies. May Allah bless this effort. Thank you.

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ABSTRACT

This project is a preliminary research on thermal performances and roof

technologies of low cost houses in Kuching. The research mainly emphasized on the

materials used in the roof construction. The aim of the project is to investigate the

thermal performance characteristics in the low cost houses whether they are providing

comfortable condition or not to occupants. The project involves temperature surveys,

which are carried out on selected low-cost houses and later an analysis is done from the

data obtained. From the data collected and analysis conducted shows that the

temperature in the house is not within the thermal comfort range. High intensity of solar

radiation cause excessive heat gain through roofs. The main factors that contribute to

this problem are improper selection of roof covering and insulation materials. From the

analysis conducted, there are a list of recommendation has been establish to increase the

thermal performance of the existing roof technologies.

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ABSTRAK

Projek ini adalah satu kajian permulaan tentang prestasi haba dan teknologi

bumbung yang digunakan dalam pembinaan rumah kos rendah di kawasan Kuching.

Tujuan utama projek ini dijalankan adalah untuk menyelidik keadaan suhu di dalam

rumah kos rendah sama ada mencapai suhu selesa atau tidak. Dalam projek ini, tinjauan

terhadap suhu dalaman rumah yang dipilih telah dijalankan dan seterusnya analisis

terhadap data-data yang diperolehi akan dilaksanakan. Kesimpulan yang telah dibuat

dalam penyelidikan ini ialah keadaan suhu dalaman rumah tidak berada dalam

lingkungan baba selesa. Jumlah haha yang mengalir ke dalam rumah melalui bumbung

adalah tinggi dan suhu dalaman rumah meningkat dengan kadar yang cepat. Salah satu

sebab utama yang menyebabkan keadaaan ini berlaku adalah disebabkan pemilihan

bahan yang tidak sesuai untuk pembinaan bumbung. Daripada analisis yang telah

dijalankan, beberapa panduan telah disenaraikan untuk mengurangkan pemindahan haba

ke dalam rumah bagi sistem bumbung yang sedia ada.

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TABLE OF CONTENTS

CONTENTS

TITLE

DEDICATION

ACKNOWLEDGEMENT

ABSTRACT

ABSTRAK

TABLE OF CONTENTS

LIST OF TABLES

LIST OF FIGURES

LIST OF NOMENCLATURES

CHAPTER ONE : INTRODUCTION

1.0 Introduction

1.1 Structure of The Final Year Project

1.2 Climate

1.3 Heat Transmission Through Roof

1.4 Types of Roof Materials

1.5 Objectives

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CHAPTER TWO : LITERATURE REVIEW 10

2.0 Introduction 10

2.1 Thermal Comfort 11

2.2 A Study of Climatic Design

2.3 Material Properties of Selected Roof Materials

2.4 Roof Technologies Available for Houses

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CHAPTER THREE : METHODOLOGY 20

3.0 Introduction 20

3.1 Data Collection 21

3.2 The Importance of Data Collection

3.3 Procedures of Conducting Survey

3.4 Environmental Monitoring System (EMS)

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CHAPTER FOUR : RESULTS AND DISCUSSIONS 27

4.0 Introductiion

4.1 Case Studies

4.2 Result

4.3 Discussion

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CHAPTER FIVE : CONCLUSIONS AND RECOMMENDATIONS 42

5.0 Introduction

5.1 Conclusions

5.2 Recommendations

5.3 Future Works

REFERENCES

APPENDIX A APPENDIX B APPENDIX C APPENDIX D APPENDIX E APPENDIX F APPENDIX G APPENDIX H APPENDIX I APPENDIX J APPENDIX K APPENDIX L

Survey Data for Bandar Baru Semariang (Green Roof) Survey Data for Bandar Baru Semariang (Red Roof) Survey Data for Taman Satria Jaya (Light Blue Roof) Survey Data for Taman Puteri (Orange Roof) Survey Data for Taman Puteri (Phase 2-Red Clay Tiles) Data Collection from EMS Roof Plan for Bandar Baru Semariang House at Bandar Baru Semariang (Red Roof) Environmental Monitoring System Retrieving Data from EMS by using computer Equipment used to Collect the Temperature Data Collecting Indoor and Outdoor Temperature

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LIST OF TABLES

Table 2.1 Reflectance values and surface temperatures of roof materials 16

Table 2.2 Thermal Conductivities of selected roof materials 17

Table 2.3 Thermal Resistance of selected roof and insulation materials 18

Table 3.1 Data collection apparatus and its functions 23

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LIST OF FIGURES

Figure 4.1 RPR Bandar Baru Semariang house (green roof)

Figure 4.2 Taman Satria Jaya house

Figure 4.3 Taman Puteri house

Figure 4.4 Taman Puteri (Phase 2) house

Figure 4.5 Solar radiation intensity versus attic temperature

Figure 4.6 Solar radiation intensity versus attic temperature

Figure 4.7 Outdoor temperature versus attic temperature

Figure 4.8 Outdoor temperature versus attic temperature

Figure 4.9 Outdoor temperature versus attic temperature

Figure 4.10 Outdoor temperature versus attic temperature

Figure 4.11 Outdoor temperature versus temperature at 1.0 metre

Figure 4.12 Outdoor temperature versus temperature at 2.0 metre

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LIST OF NOMENCLATURES

°C - degree Celsius

°F - degree Fahrenheit

K- degree Kelvin

W/m2 - watt per square meter

W/m" K- watt per meter degree Kelvin

mm - millimeter

kg/m2 - kilogram per cubic meter

hr - hour

m/s - meter/second

m- meter

a. m. - morning

p. m. - evening

"C" m2/W- meter squared degree Celsius per watt

BBS - Bandar Baru Semariang

K-value - Thermal Conductivity value

R-value - Thermal Resistance value

%- per cent

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CHAPTER ONE

INTRODUCTION

1.0 Introduction

The demand for low cost and medium cost housing units is extremely high in

Malaysia. Under the Fifth Malaysia Plan, about 500,000 units of low cost houses are to

be completed by 1990. This constitutes about 70% of the total units of 701,500 houses

that are required to be built during the year of 1985 - 1990. By the end of the Sixth

Malaysia Plan (1991 -1995), it is estimated that 45% of rural populations will be living

in urban areas. In the Seventh Malaysia Plan (1996-2000) the demand for houses is

expected to increase and a total of 800,000 units of houses will be required. The selling

price for each of the single storey terrace low cost houses is between RM

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25000 to RM 35000. The targeted population is for people that monthly income is

between RM 750 to RM 1200. The pressing need to produce a reasonably cheap

structure for houses will affect the quality produced. On the other hand, if the quality is

to be maintained, then the price of the structure will increase (Ramli and Md. Nordin,

1994). Therefore, the challenges are to build a house that is cheaper but compatible to a

system of housing. Alternatively, a new design system and construction techniques are

essential for the development of future low cost housing system.

Architects, planners and engineers have always been involved in these housing

projects, but sad to say, they have neglected one very important factor in the design and

planning of the housing unit, the climate. This is mainly due to economic reasons, but

what the people need is not only a house, but a comfortable dwelling place. Designs

have evolved through the years, but climate, as a major design parameter, has still been

left out of the designer's considerations (Luna, 1997). The mass housing programs also

resulted in dwelling units which are not designed suitable for the warm-humid tropical

climate of the country (Rajeh, 1994).

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1.1 Structure of the Final Year Project

This Final Year Project Report consists of five main chapters. The first chapter is

the introduction part, which consists of the objectives of this project and defines

different shapes and structures of roof. There is also an explanation on how the heat is

transferred to the roof structure and determines the factors that affect the thermal

performances of the roof due to local climate.

Chapter Two consists of literature review which describes different type of

materials used in roof constructions from roof cover until the insulation layer and roof

technologies used in Low-Cost Houses to achieve thermal comfort. It also defines the

thermal comfort of the local climate.

Chapter Three describes the methodology of this research project, covering

sections on how the data is collected. The importance of each data collected is also

discussed here. Then, the procedures of thermal performance survey in the selected

houses are highlighted.

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Chapter Four describes the data on temperatures obtained from the case studies.

The data is presented using tables and graphs. The analysis of the data collected also

being carried out in this chapter.

Chapter Five is mainly for conclusions and recommendations of the project. All the

results and findings obtained are summarized here. The recommendations regarding the

roofing materials also presented in this chapter. The last part of this chapter discussed

about future works that is associates with the research.

1.2 Climate

In order to achieve climate comfort level in the house, deep understanding and

evaluation about climate condition in the local area is needed. The main causes of

climatic stress in Malaysia are high temperature (uniform temperature), solar radiation,

humidity and glare. The climate of Malaysia can be classified as warm-humid

equatorial, characterized by high temperature and humidity. Air temperature averages

between 22°C and 32°C with small annual and diurnal ranges.

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Humidity is high throughout the year, averaging about 75% or more. With heavy

cloud cover and high water-vapour content in the air, direct solar radiation is filtered.

Although reduced, solar radiation is strong and can cause painful sky glare.

Winds are generally of low-variable speed. Strong wind can occur with the rains.

Winds come in two dominant directions, from the northeast and southwest. Though the

wind over the country is generally light and variable, there are, however, some uniform

periodic changes in the wind flow patterns. Based on these changes, four seasons can be

distinguished, namely, the southwest monsoon (April to October), northeast monsoon

(October to February) and two shorter inter-monsoon seasons. The prevailing wind flow

is generally southwesterly and light, below 15 knots.

Rainfall is also high throughout the year, averaging 250 to 300 cm annually. The

seasonal wind flow patterns coupled with the local topographic features determine the

rainfall distribution patterns over the country. During the northeast monsoon season, the

exposed areas like the east coast of Peninsular Malaysia, Western Sarawak and the

northeast coast of Sabah experiences heavy rain spells. On the other hand, inland areas

or areas which are sheltered by mountain ranges are relatively free from its influence.

Rainfall distribution is mainly due to seasons. Rain often comes in short, strong bursts

and generally hides the sun temporarily.

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1.3 Heat Transmission Through Roof

Heat is transmitted through roofs in three mechanisms. There are radiation,

conduction and convection. When solar radiation or solar energy strikes an exposed

material, some of the energy is absorbed, some is reflected, and a portion may be

transmitted through it. Lost heat energy seeks its own "lowest level", that is, it always

migrates from spaces or material of higher temperatures to those of lower temperatures

(Watson and Labs, 1992). Sun as a source of solar energy that produce heat from

radiation will strikes the roof cover. The roof cover absorbs heat and temperature rises.

Heat is conducted by roof cover to the air, which transports heat by convection within

the attic area above the ceiling causing the air temperature in attic area to rise. Then,

heat is conducted by ceiling to the air which transports heat by convection within the

living area causing the air temperature in the living area to rise. Cowan and Smith

(1983) define that convection is due to fact that most liquids and gases change their

density as they change their temperature. Generally they get lighter as they get hotter.

From the flow of the heat, it can be conclude that the selection of material with

suitable thermal properties is the important criteria to be considered in order to

minimize heat transmission into the house, thus guided towards achievement of thermal

comfort. Selection of roof coverings and installation of thermal insulation can be a

major parameter to determine thermal performances of the dwellings. The parameters

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that can be considered in selecting the appropriate material are such as thermal

conductivity (K-value), surface reflectance and thermal resistance (R-value).

1.4 Types of Roof Materials

There are different types of roof materials used in practice. It is depend on factors

such as climate, economical and available of materials, topography and also aesthetics.

Each of the roofs also has it own characteristics.

For the roof cover, it is dependent on types of material used. For tile or shingle roof

top, it can be in form of materials such as clay, cement, concrete, wood, asphalt and

slate. In fact, because of its extreme durability, longevity and safely, tile roof is the most

prevalent roofing material in the world. Because of the thermal capacity of roof tiles and

the ventilated air space that their placement on the roof surface creates, a tile roof can

lower air conditioning costs in hotter climates. Tile roofing system is made from

naturally occurring materials and can be easily recycled into new tiles or other useful

products.

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While other roof cover such as metal roof sheathing consists of steel or aluminum,

although some consists of copper and other metals. Steel is invariably galvanized by the

application of zinc or zinc/aluminum coating, which reduces the rate of corrosion. Metal

roofing is available as traditional seam and batten, tiles, shingles, and shakes. Products

also come in a variety styles and colours. There also metal roof made from monel.

Monel is a substitute for stainless steel and is very corrosion resistant. Monel contains

iron, manganese, silicon, nickel and copper. Due to heat transmission, it is important to

determine the K-value of each roof materials selected as roof coverings. From the K-

value, the time for the heat to be conducted through roof can be predicted. The colour of

the roof surface or coatings also plays a significant role due to heat transfer because it

has its own reflectivity value. Some portion of solar energy is reflected when its strikes

the roof surface. Thus, selection of surface colour of roof coverings also contributing to

the thermal performances of roofing materials.

In modern design, installation of insulation layer to control heat transfer through

roof is needed. Two main types of insulation are bulk insulation and reflective

insulation. Bulk insulation materials have tiny pockets of trapped air. These pockets

resist the transfer of heat through material. The important parameter to be considered

when selecting the insulation layers is its resistant value (R-value). Some examples of

bulk insulation are cellulose fibre (finely shredded recycled paper), fiberglass, rockwool

and polystyrene. For reflective insulation is in forms of metallic foils, laminated to

paper and reinforced with glass fibres. It works by reflecting significant proportions of

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light and heat. In practice, usually we found reflective insulation and bulk insulation

bond together to increase the performance of the insulation.

Usually in construction of terrace houses for low-cost houses in Malaysia, the roof

design used is mainly in the shape of hipped to give response to country climate(hot

humid climate) and the aesthetical value. The types of roof cover used are usually made

from metal. Installation of insulation layer is depending on specifications.

1.5 Objectives

The objectives of this project are as follows:

a. To collect information about roofing materials used in low cost houses through

literature review and blue prints (if available) that is given by the developers.

b. To analyze the data collected and describe the factors that affected the thermal

performances of existing roofing materials.

c. To determine whether the thermal condition in the selected low cost houses is

within the thermal comfort range.

d. To provide recommendation on suitable roofing materials for future low cost

houses development especially in hot humid climate.

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CHAPTER TWO

LITERATURE REVIEW

2.0 Introduction

This purpose of the literature review is to investigate the available of roofing

materials and their thermal properties. Other areas associated with the study were

research that has been done to determine roofs thermal performances and available roof

technologies in hot humid climate.

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2.1 Thermal Comfort

For building design and engineering purposes, human thermal comfort can be

defined as the state of mind which expresses satisfaction with thermal environment

(Watson and Labs, 1983). This range plotted on the bioclimatic or psychometric charts

varies with climates and is affected by an individual's clothing, geographical location,

age and sex. This zone is based on the air and surface temperatures, the relative

humidity and air movement (Luna, 1997). J. Moss (1998) defined that the core

temperature of human body is taken as 37.2°C and discomfort will occur if the body

temperature varies much from the core temperature. Based on various researches in

determining comfort temperature range in Malaysia, the range that could be applied as

thermal comfort for design purposes is between 24°C to 27°C during daytime (Hanafi,

1999). This project will be based on this range of comfort temperature zone for

comparison in each of the case studies.

2.2 A Study of Climatic Design

The condition of hot humid climate in Malaysia has a great impact on design of the

building envelope to achieve thermal comfort in the house. Indonesians architect,

Kisnarini (2000) conclude that low conductivity materials, high air changes and shading

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devices have important roles in improving indoor temperature especially for hot humid

climate area. More over, with the small conductivity usually create small thermal

capacity. In the hot humid climate condition, the high temperature and high relative

humidity permit no heat storage at all, or heat gain. Accordingly, small thermal capacity

even zero thermal capacity is more preferable.

Yuan (1999) found that the lightweight construction of the Malay house with

minimum mass and much voids, using low-thermal-capacity and high-insulation

materials, is most appropriate for thermal comfort in our climate. The wood, bamboo

and "attap" used have good insulating properties and they retain or conduct little heat

into the building.

Luna (1997) in his study over thermal performances of existing low-cost housing in

Philippines conclude that building materials to be used in construction should not store

the heat absorbed during the day. Heat storage and time lag should be minimal,

meanings materials should be lightweight and cool down quickly in order to achieve the

improved comfort conditions required at night for sound sleep, as the human body is

more sensitive to the climate when it is at rest. High reflectivity and emmissivity are

also important properties of materials as they keep the indoor temperature and inner

surface temperatures low as in the case of double leaf construction for the roof.

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All building materials have insulating value since all provide some amount of

resistance to the flow of heat. Based on various studies and research has proved that

insulation can resist and minimize the heat flow through building envelops. Thermal

resistant (R-value) of bulk insulation is depend on thickness, density and nature of the

insulating materials. Many pockets of still air are low, which means that a greater

thickness of insulation is required to achieve the same R-value as other denser product.

While reflective insulation usually used is in forms of metallic foils. To optimize their

effect, the shiny metallic surfaces must be adjacent to a still air gap or cavity of 25mm

or more for relieving heat gain from roof (ventilation).

The colour of the external surfaces of the roof has a tremendous effect on the

impact of the sun on the building and on the indoor temperature. For example, black

absorbs about 85 to 100 per cent, dark green and grey 70 per cent, light green and grey

40 per cent, white oil paint 20 per cent, white emulsion paint 12 to 20 per cent, and new

whitewash 12 per cent (H. Seeley, 1995). Givoni and Hoffman, (1968) reported an

extensive studies on the effect of the colour of roofs and walls on the heat transmitted

into a building. These results conclude that a highly reflected colour (white) used on an

envelope is cost effective way to reduce the building heat gain as it does not involved

extra cost. The difference in the maximum external surface temperature between white

roof and a black one in a desert in a summer can be 30°C to 40°C. Peter Davis(2001) in

his research on steel roof thermal performance has found that the surface temperature of

a white steel roof is 13 degrees cooler and the roof stores 30 times less heat compared to

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