The study of natural ventilation in terrace housing: a case study at Seri Iskandar, Perak. RAABIAH AL ADAWIYYAH BT YAACOB 2008215986
TABLE OF CONTENT ABSTRACT……………………………………………………….ii DECLARATION…………………………………………………..iii VERIFICATION…………………………………………………..iv TABLE OF CONTENTS……………………………..................1 LIST OF FIGURES……………………………………………….3 ACKNOWLEDGMENT…………………………………………..4 CHAPTER 1: INTODUCTION………………………………..…5 1.1
CHAPTER 2: LITERATURE REVIEW…………………………9 2.1
Natural Ventilation: Definition and Theory……………10
Mechanisms of Natural Ventilation……………………14 2.3.1 Wind Driven Ventilation………………………...14 2.3.2 Stack Driven Ventilation………………………..18
Building Openings………………………………………22 2.4.1. Opening Types ………………………………....22 2.4.2. Opening Location……………………………….27 2.4.3. Opening Size And Shape……………………...29 1
The study of natural ventilation in terrace housing: a case study at Seri Iskandar, Perak. RAABIAH AL ADAWIYYAH BT YAACOB 2008215986
CHAPTER 3: METHODOLOGY………….……………………31 3.1
Study / Approach………………………………………31
The Phase of Study……………………………….…..32
CHAPTER 4: DATA COLLECTION AND FINDINGS……….34 4.1
Data Analysis and Findings ………...………………37
CHAPTER 5: CONCLUSION AND RECOMMENDATION…48 CHAPTER 6: REFERENCES……………………………….…51 CHAPTER 7: APPENDIX………………………………………54
The study of natural ventilation in terrace housing: a case study at Seri Iskandar, Perak. RAABIAH AL ADAWIYYAH BT YAACOB 2008215986
LIST OF FIGURES Figure 1: The principle in cross- ventilation.....................................14 Figure 2: The principle in single-sided ventilation...........................14 Figure 3: Windward and leeward pressure.....................................15 Figure 4: Positive and negative force in stack effect......................18 Figure 5: How the difference of indoor and outdoor temperature affects stack effect...........................................................................19 Figure 6: Pressure is affected by the height difference between openings..........................................................................................21 Figure 7: Fixed louvered windows...................................................25 Figure 8: Fin walls...........................................................................25 Figure 9: Fixed louvered windows...................................................25 Figure 10: Jacked roof and stack effect..........................................26 Figure 11: Seri Iskandar map..........................................................34 Figure 12: Taman Teknologi Seri Iskandar.....................................35 Figure 13: Temperature chart of Seri Iskandar...............................36 Figure 14: Wind speed chart of Seri Iskandar................................36 Figure 15: Terrace house layout plan.............................................37 Figure 16: Terrace house elevations...............................................38 Figure 17: House 1 front elevation..................................................38 Figure 18: House 1 rear elevation...................................................38 Figure 19: House 2 front elevation..................................................39 Figure 20: House 2 rear elevation...................................................39 Figure 21: House 3 front elevation..................................................39 Figure 22: House 3 rear elevation...................................................40 Figure 23: House 4 front elevation..................................................40 Figure 24: House 4 rear elevation...................................................40 Table 1: Comparison of four selected houses.................................42
ACKNOWLEDGMENT First of all, I would like to thank my mentor, Encik Zakaria B. Yaaâ€™cob
suggestions in reviewing research. He also helps me a lot in understanding this subject and the topic that I picked. Even during nonworking hours, he is willingly to see me and help giving me ideas and suggestion to finish this paper. Without his help, I will not be able to complete this research within the prescribed time.
Secondly, I would like to express my gratitude to the staffs at Seri Iskandar Development Corporation Sdn Bhd. Especially to Encik Kamal that have troubled himself finding the working drawing of the plans and elevations of the terrace house in Seri Iskandar.
Next, I would like to express my thanks to all the interviewee from Taman Teknologi Seri Iskandar residential that not only let me when through their house to collect the data that I wanted but also have been given me full corporation during the interviews and answering my questioners with commitment.
especially to all those whose with me when Iâ€™m challenges in
given encouragement, support and assist me in this industry.
CHAPTER 1: INTRODUCTION
1.1 INTRODUCTION Human body response intelligently to different climate conditions by acclimatization and adaptation. The difference of human thermal comfort behaviour for different climate condition has clearly shows that the design of certain building must comply with the local climate and environment. Residential building, particularly terrace house in Malaysia nowadays is often related to issues such as overheating, and inadequate thermal comfort.
Using the mechanical ventilation such as air conditioner has been very popular in this industry to overcome the overheating issues. But mechanical ventilation systems are not good for environment and expensive to run. By maximising passive design in our buildings, we are not only saving energy but also the environment. Ken Yeang (1999), stated that AC cannot be abandoned in the tropics but passive techniques can reduce the need for mechanical cooling devices. Architecture plays an important role in overcoming issues that affect our environment and lifestyles. However, in order to achieve the thermal comfort that is suitable and affordable for Malaysian low cost residence, the natural ventilation strategy must be studied and understand.
This research represents the study of natural ventilation in terrace housing in Malaysia. The types, design strategy and also application of the techniques will be studied. During this research, 5
an instrument in a the form of survey questionnaires and measurements on the effectiveness of natural ventilation in low cost terrace housing area at Seri Iskandar residential area at Bota, Perak will be developed. This study began with the selection of four units of residential house, randomly picked located in at Seri Iskandar, Perak as the case study project. They were then will be compared with the efficiency of natural ventilation standard as well as precedent studies on the subject. Finally the results will indicate whether that the natural ventilation performance of terrace housing in Malaysia works or not.
1.2 PROBLEM STATEMENT
Energy shortage is currently one of the most important worldwide concerns. There has been an enormous increase in the global demand for energy in recent years as a result of industrial development and population growth. In hot and humid climate such as Malaysia, energy consumption in building sector, especially in residential buildings, accounts for a large portion of the consumption for the whole country. In order to contribute to conserve the energy, an architect can help by trying to adapt passive building design especially in the residential building sector. One of the techniques that can be applied is by maximizing natural ventilation in the building. Natural ventilation represents one of the main criteria in the evaluation since it can create thermal comfort for occupants and help save large amount of energy from mechanical ventilation systems.
However, since the invention of air conditioners and other mechanical ventilation, architects began to cooling move away from passive techniques and relied on them to achieve thermal comfort. But not only mechanical ventilation systems are expensive to run, but not good for environment. Therefore, the design of the building itself must play the important role in minimising the use of mechanical ventilation. The architect himself must be able to design a house that maximise the use of natural ventilation in achieving thermal comfort for people inside the building.
In Malaysia, the design of low cost housing does not reflect the efficiency of natural ventilation that have been studied. The initial cost is more being concern rather than the afterwards 7
maintenance. Hence, the passive design and the passive natural ventilation design are left out and the occupant will have no option than to use massive mechanical ventilation in order to achieve their comfort zone. This does not only indicates poor design, but also does not have the features of the sustainable buildings that needs to be adapted starting from today.
1.3 OBJECTIVE 1. To better understand the definition of natural ventilation 2. To identify and investigate the natural ventilation strategy in housing designs. 3. To determine whether natural ventilation in low cost housing in Seri Iskandar comply the passive design strategy.
1.4 SCOPE This research will be focused on four randomly picked terrace houses in Seri Iskandar housing area. All the terrace houses will be studied by the types, size and shape as well as location of the openings. The occupants of all the houses will also be interviewed to strengthen the data collection and analysis. The study adopts a case study approach which involves only a sample group of respondent.
CHAPTER 2: LITERATURE REVIEW
2.1 INTRODUCTION According to Abdul Malek Abdul Rahman, (2004) Malaysia is situated between 10째N and 10째S, within the Equatorial Zone and therefore the climate can be classified as warm and humid equatorial.
This is characterized by the high ambient
temperatures with air temperatures averaging at 23째C for the minimum and 33째C for the maximum with small diurnal and annual
throughout the year averaging more than 80% relative humidity.
Even though there are high cloud cover and high water vapour content in the air, the heat is still stifling and unbearable under direct exposure. Even on a good day the sunshine is strong enough to cause painful sky glare. With high humidity and high air temperatures we need more wind for thermal comfort. To achieve thermal comfort in a more sustainable way, one should consider a design that promotes natural ventilation when designing a house. This chapter seeks to explain more about what is natural ventilation in definition and theory and also to show the passive approaches that can be use in order to achieve natural ventilation in buildings.
With some passive cooling system, temperatures are actually lowered and not just minimized as is the case with heat avoidance. The passive cooling strategies through ventilation will be discussed in this chapter.
2.2 NATURAL VENTILATION : DEFINITION AND THEORY A ventilation system is a composition of components for ventilation.
Dictionary, sixth edition, edited by Catherine Soanes et. al ventilation means to cause air to enter and circulate freely in a room or building. “Natural ventilation is caused by pressure difference at the inlets and outlets of a building envelope, a result of wind velocity and/ or stack effect.”
(M. Santamouris and D. Asimakopoulos, 1996)
According to Francis Allard and Matheos Santamouris (1998) in their book, Natural ventilation is essential to ensure the sufficient indoor air quality in the building. It is the process by which fresh air is introduced and ventilated air is removed from an occupied space. Sometimes, ventilation may also be used to lower the temperature inside an occupied area. Natural ventilation can be defined as ‘the movement of air through openings in a buildings fabric, due to wind or to static pressures created by the differences in temperature between the interior and exterior of the building, or to a combination of these acting together’, stated Mazran Ismail & Abdul Malek Abdul Rahman(2012). Natural ventilation is subject to the variability of wind speed, wind direction, air temperature and opening configuration. These are not the only factors affect the rate of fresh air supply, the openings that act as an inlet or outlet for the
air in any space within a building also play the role in the effectiveness of natural ventilation.
Building components that affect natural ventilation include shape of the building, geometrical configuration, orientation
subdivision of interior space.
(Givoni, B., 1994)
Factors that influence these parameters can generally bedivided into two parts: outdoor environment and building component.
(Professor Chalermwat Tantasavasdi et. al, 2007)
Unlike fan-forced ventilation, natural ventilation uses the natural forces of wind and buoyancy to deliver fresh air into the buildings. It is the process of supplying and removing air to an indoor space without using mechanical systems by means of purpose-provided
ventilators and shafts) and the natural forces of wind and temperatures-difference pressure. â€œIn naturally ventilated buildings, no energy is needed for moving the air,â€?
(Francis Allard and Matheos Santamouris, 1998)
Most often natural ventilation is assured through openable windows or trickle vents when the spaces to ventilate are small 11
and the architecture permits but it can also be achieved through different temperature and pressure between spaces.
For air to move in and out of the building, a different pressure between the inside and outside of the building is needed. The opposition to flow of air through the building will affect the actual rate of air flow. In other word, a controlled natural ventilation and infiltration are driven by the difference of the pressure across the building envelope. The pressure difference is caused by wind (or wind effect), the difference in air density due to temperature difference between indoor and outdoor air (stack effect) or combination of both wind and stack effect.
It is known that natural ventilation can be generated by two methods: by thermal force or buoyancy effect, and by wind pressure force orwind-driven effect. In general, winddriven natural ventilation is easier to achieve because it only needs a low wind speed to create adequate indoor air velocities that help peopleâ€™s heat transfer by means of evaporation.
(Tantasavasdi et. al, 2001) From what have been stated above, there are two types of natural ventilation occurring in buildings: Wind driven (cross ventilation) ventilation and Stack driven ventilation. Wind driven ventilation is depending upon the force of the current wind to pull and push air into the building through the enclosed space. By practicing the passive design of the building, Wind Driven Ventilation can be utilise by of the natural passage of air without the high need for energy consuming equipment. 12
Buoyancy ventilation on the other hand driven by temperature (known as stack ventilation) or by humidity (known as cool tower). Most commonly used is the stack driven ventilation. When there is a temperature difference between two adjoining volumes of air the warmer air will have lower density and be more buoyant thus will rise above the cold air creating an upward air stream. For stack ventilation to work efficiently a temperature difference is a must. But, stack driven ventilation is limited to a lower magnitude than wind driven ventilation. It is also very relying on the differences of the inside and outside temperature. During hot weather when air conditioning produces lower temperatures inside than outside, the reverse process occurs.
2.3 MECHANISMS OF NATURAL VENTILATION 2.3.1 Wind Driven Ventilation Wind driven ventilation or roof mounted ventilation design in buildings provides ventilation to occupants using the least amount of resources. By utilising the design of the building, wind driven ventilation takes advantage of the natural passage of air without the need of high energy consuming equipments.
From what have been point out to Tine Steen Larsen (2006), wind-induced ventilation uses pressures generated on the building by the wind, to drive air through openings in the building. It is most commonly realised as cross-ventilation, where air enters on one side of the building, and leaves on the opposite side where there are openings in more than one wall so that the air crosses the room, but can also drive single sided ventilation where there are only openings in one wall.
Figure 1: The principle in cross- ventilation
Figure 2: The principle in single-sided ventilation
â€œTwo-sided or cross ventilation occurs when air enters the room or building from one or more openings on one side of the room and leaves through one or more openings on the other side of the room or building.â€? (Hazim Awbi, 2003)
As stated in his book, cross ventilation is more effective than single ventilation since the larger air flow rates can be provide, hence it is suitable for larger heat gains. The single-sided ventilation also lacks adequate air flow control unless automated openings are used.
According to Gohui Gan (2010) in his journal, The Open Construction and Building Technology, wind can assist and oppose buoyancy in the windward and leeward wings at the same time, respectively. Hazim Awbi (2003) also stated when air flow is due to wind; air enters through openings in windward walls, and leaves through openings in leeward walls. Wind causes a positive pressure build up on the windward (wind facing) side of the building causing it to have higher pressure than the static pressure of the wind and a negative pressure on the leeward side which the creates a net pressure difference across the building and induced the wind for cross-ventilation.
Figure 3: Windward and leeward pressure 15
“Two-sided or cross ventilation takes place when air enters the building on one side, sweeps the indoor space and leaves the building on another side.”
(Mat Santamouris and Peter Wouters, 2010)
It is really important to avoid obstructions between the windward inlets and leeward exhaust openings. Avoid partitions in a room oriented perpendicular to the airflow. On the other hand, accepted design avoids inlet and outlet windows directly across from each other, in order to promote more mixing and improve the effectiveness of the ventilation. The flow of air in this case is mainly due to wind pressure, and buoyancy pressure becomes important only if there is significant difference in height between the inflow and outflow openings. “Cross ventilation is suitable for spaces of depth <2.5H, where H is the ceiling height and up to 5H.
(Hazim Awbi, 2003)
The orientation of the building towards prevailing wind also determine the pressure distribution on building. In Malaysia, east and west is exposed in sun radiation every morning and evening. Therefore, building orientation, particularly in tropical design must me considered to the interaction with sun and wind direction for natural ventilation and maximum gain of thermal comfort.
“In predominantly hot humid regions like Malaysia which receives sunlight all year around, buildings should be oriented to minimize solar gain and maximize natural ventilation.”
(Nedhal Ahmed M. Al-Tamimi, et. al, 2011)
S. Barrington (1992) reported a case study that investigate the impact of orientation of buildings and rate of natural ventilation. In his experiment, a typical swine barn with panels and chimneys designed for adequate natural ventilation was selected. The barn is tested with six different orientation, which is 0°, 30°, 60°, 90°, 120°, 150° from the northerly direction, in the same site. The wind data and calculation of the natural ventilation rates is recorded. From his experiment, the building orientation of 30°, and 60° from the northerly direction gave the lowest ventilation rate while 120° and 150° gave the highest. This had proved that the orientation of the building greatly effects the natural ventilation. “Because of the pressure difference crated by natural phenomena, the adequate ventilation of the shelter depends solely on the proper design (sizing and location) of inlets and outlets as well as suitable orientation of the building relative to prevailing winds.”
(S. Barrington et al, 1992)
2.3.2 Stack Driven Ventilation Suggested by Abdul Malek Abdul Rahman (2004) stack effect is a natural process temperature induced, where air hot rises and is driven out of buildings, chimneys, flue gas stacks, or other containers, by vertical pressure differences developed by thermal buoyancy. The buoyancy or stack pressure at an opening is occurs due to variation in indoor-to-outdoor air density resulting from temperature and moisture differences. The density of air depends on temperature and humidity (cool air is heavier than warm air at the same time humidity and dry air is heavier than humid air at same temperature). Thus, the result is either a positive or negative buoyancy force.
Figure 4: Positive and negative force in stack effect
As we know, as air is heated it becomes less dense and rises; as air cools it becomes denser and falls. Hazim Awbi (2003) also stated that stack effect occurs when there is a difference
temperature, and different pressure across the openings and for openings at different heights. When air movement is due to 18
temperature difference between the indoor and outdoor, the flow of air is in vertical direction and is along the path of least resistance.
differentials and therefore pressure difference, that drive the air to move.
If the inside air temperature is warmer than the outside air, it will be less dense and more buoyant and will rise through the space. This creates a relatively high pressure zone in the upper level of the building. The warm air inside the building is less dense than cooler air outside, and thus tend to exhaust from the space openings high up in the building envelope; it will be replaced by cooler, denser air drawn into the relatively low pressure zone in the bottom floor of the building. (Mike Thompson, 2000)
Indoor air warmer than outdoor
Indoor air cooler than outdoor
Figure 5: How the difference of indoor and outdoor temperature affects stack effect
The stack effect process will continue if the air entering the building is continuously heated, typically by casual or solar gains. Within the room, heat and humidity given off by occupants and other internal sources both tends to make air rise. The stale, 19
heated air escapes from openings in ceiling or roof and permits fresh air to enter lower openings to replace it. ”The driving stack pressure varies with building heights, and
(Mat Santamouris and Peter Wouters, 2010)
Hazim Awbi (2003) also quoted that in stack ventilation buoyancy is the main driving force and the height of the stack becomes significant. It also increases as the height of the building increases, i.e. the difference in height between air inlet and exhaust, a neutral plane, where internal and external pressure are equal, will exist somewhere between. Above the neutral plane the internal air pressure will be positive relative to the neutral plane and air will exhaust through any available openings. Below the neutral plane, the internal air pressure will be relatively negative and external air will be drawn into the space. The further away a space is from the neutral plane, the greater the pressure difference and the greater the airflow in that space. “Depending on the position of air inlet and outlet in the building, the wind pressure could assist the stack pressure, reduce its influence or indeed reverse the effect, i.e. by forcing the air through outlet.”
(Hazim Awbi, 2003)
Figure 6: Pressure is effected by the height difference between openings
Based on what have been quoted above, we can conclude that the stack are incorporated in the building, and therefore must be careful design to avoid these adverse effects from occurring. Stack ventilation occurs naturally whether we design it or not, and has been consciously used for centuries, in traditional and vernacular buildings ranging from Indian tepees to churches. However, modern analysis and design advice greatly extends its area of application to much larger buildings, with more exacting demands.
2.4 BUILDINGS OPENINGS 2.4.1 Opening Types
Adjustable buildings openings can be either doors or windows. There are two types of doors that are commonly used in housing design. The most common doors are hinged doors while there are several types of windows that is widely used. Doors could be hinged or sliding. Hinged doors are used in most housing design while sliding door is used by several only. Windows also existed in hinged and sliding types. The effect on the wind flow through the building can varies depending on the type of windows and doors. The effect of a door of the s types is almost the same as windows except that it is bigger in size.
The type of window will affect not only the open area for air flow but also effect of the wind and buoyancy pressure acting on the window itself.â€?
(Hazim Awbi, 2003)
Relatively large windows are frequently used for airing and for indoor air quality control. They can be louvered, turning and sliding windows or combination of these. Comfort condition and the use of windows are very dependent upon weather conditions, such as outside temperature, wind and rain. From what have been stated by Mat Santamouris et. al (2006), doublesliding windows give the best performance since the advantage of a double-sliding window is twofold: one can control the flow 22
rate easily by adjusting the position of the two opposite window panes. At the same time, one can adjust air velocity to the room by adjusting the opening to the room in such a way that comfort problems during hot temperature environment will not occur as frequently as in case of side-hung turning windows. Most modern homes use this type of window. Sliding windows are also air tight and energy efficient.
Side-hung or casement windows are used quite frequently in moderate climate like Malaysia. People do not use them only for ventilation or indoor air quality control, but also for temperature control since it allows almost full air flow. But they can also deflect the air stream. Based on Hazim Awbi (2003) statement, this kind of window has smaller effective opening, hence lower the air flow into the building.
While a louvered window uses strip of glass or wood that are constructed at an angle for ventilation. It can be adjustable or fixed. An adjustable louvered window is operated by a lever that opens and closes the set of angled wood or glass. Jalousie is a subtype of a louver window where the glass louvers overlap. It is commonly used in Seri Iskandar housing area. This window type is not energy efficient as it is not airtight. This type is not very secure too as the louvers can easily be taken apart. But however, as Norbert Lechner (2001) pointed out, these type of window features deflect the rain while simultaneously still provides air which is very important in hot and humid climate such as Malaysia.
“Louvered window is ideal for tropical climate as it can be adjusted to allow lights and variable openings for ventilation while at same time prevent rain from entering the interior. With translucent glass it provides privacy and yet ventilation.”
(Abdul Malek Abdul Rahman, 2004)
Fixed louvered window can also be considered as fin walls. Fin walls can greatly increase the ventilation through windows on the same side of a building by changing the pressure distribution. But, each window must only have only a single fin. Fin walls will not work when they are placed on the same side of each window. “A fin wall can be used to change the pressure balance and thus, the direction of the air stream.”
(Norbert Lechner, 2001)
Just as louvered openings in windows, louvered walls not only allow wind to pass through but also provide natural lighting during daytime. According to Abdul Malek Abdul Rahman (2004), there are many types of louvered walls such as inclined louvered walls, louvered walls of fixed concrete, and ventilation blocks as a variation of louvered walls.
Both of the fixed louvered window and fin walls can be categorised as wind deflector. Wind deflectors are also one of the devices used as a mechanism for natural ventilation. It used fixed louvered window and fin walls to direct wind flow to the interior. It can be either horizontal or vertical.
Figure 7: Fixed louvered windows
Figure 8: Fin walls
Figure 9: Fixed louvered windows
â€œHot air rises. In building, this natural process is termed as stack effect. With the combination of body heat, light source, cooking activities and building internal re-radiation, it creates the potential for internal flow even under calm outdoor conditions.â€?
(Abdul Malek Abdul Rahman, 2004)
From what has been point out, stack effect is involved in this situation of removing hot air naturally. In this situation, roof vents, cupolas and monitors are designed to release hot air from trapping underneath the ceiling inside of the house. In Malaysia, roof monitors known as the jacked roof are designed to release hot air that rises from the interior of the building by stack effect.
Figure 10: Jacked roof and stack effect
2.4.2 Opening Location â€œWind
perpendicular to a surface. And the pressure is reduced about 50 percent when the wind is at oblique angle of about 45 degrees.â€?
(Norbert Lechner, 2001)
Norbert Lechner (2001) also added, as a result of a result of the case a fairy large range of wind direction will work for most designs. Since it is very rare that winds blowing mainly from one direction, this is consider fortunate. It might not be possible to face the building to the wind, even where the strong prevailing directions. Ventilation from windows on adjacent wall can be either good or bad, depending on the wind direction and location of the window.
The location of inlets and outlets should be determined due regard to wind direction. The open leaf of the door could direct the wind direction. Air inlets that is positioned on the leeward side of the building may be subjected to negative pressures, which will tend to reverse the movement of air, causing unwanted air to move downwards rather than upwards toward the vents.
The placement of openings on wall determine not only the quantity but also the initial direction of incoming air. For example, sometimes wind flow prevails parallel to a building wall rather that perpendicular to it. In this case it is still possible to induce wind ventilation by the way a casement window opens. For 27
example, if the wind blows from east to west along a north-facing wall (which open out) would have hinges on the left-hand side to act as a scoop and direct wind into the room. The second window would hinge on the right-hand side so that the opening is down-wind from the open glass pane and negative pressure draws air out of the room.
Based on what have been stated by Norbert Lechner (2001), the placement of the building openings is determined by the purpose of air flow. For comfort ventilation, the openings should be low, and at the level of the people in the room. The place of the opening should be between 1 and 2 feet above the floor. A low opening is important when using hopper or jalousie window because of their tendency to deflect air upward. R.M.J Bokel (2007) also stated that it is also a little advantageous when the primary energy load for heating is considered, especially for small window sizes. The highest window position does not perform much better than the medium window position. However, additional high openings, like ceiling vents or clerestory windows should be considered for exhausting hot airs that collect near ceilings. High openings are very important for stack effects, Luiz Busatoi (2003)
2.4.3 Opening Size and Shapes
“Opening size and shape are important factors that determine the airflow within buildings.”
(Luiz Busatoi, 2003)
Windows and doors act as the opening for some spaces or a building. Hence, from what have been stated above, it has quite a major impact on the ventilation rate for a building. This is because, the bigger the size of openings the better the ventilation rate of a building. But there is also a limit. After a certain point, there will be an optimal level of ventilation for a building. From what have been discovered by R.M.J. Bokel (2007), an optimal opening size for simulation is around 30% of the façade area, but an opening size of 20% to 40% is also very acceptable. For larger window sizes, starting at 50%, the advantage of a larger glass area on the lighting load is negligible. As a larger window area increases the cooling load significantly, the net primary energy load increases for larger window sizes. “Generally the inlet and outlet should be about the same size since the amount of ventilation is mainly a function of the smaller opening. However, if one opening is smaller, it should be the inlet because that will maximises the velocity of the indoor airstream, thus gives the greatest effect of comfort.”
(Norbert Lechner, 2001) 29
A case study is done by Nedhal Ahmed M. Al-Tamimi (2011), which selected a building located in University Malaysia Penang consisting four storeys, and functions as student dormitory complex. Two rooms were used for his study, the first facing east orientation and the second west orientation. The overall floor area for each room is 12.9 mÂ˛, the building is oriented in such a way that openings have mainly exposure to east and west direction, the window-to-wall ratio of both rooms is 50 %. The existing rooms are then compared to the window wall ratio of 25% and 0% (shutting window completely). In his experiment, In the 50% window wall ratio, both roomsâ€™ temperature slightly decreased compared to the 25% and 0% of window wall ratio. From the case study he has found that the net effect of the window system in building envelope design depends greatly on the window wall ratio.
CHAPTER 3: METHODOLOGY
STRATERGY / APPROACH
Combination of qualitative and quantitative methods. Qualitative methods were the major approach mainly from observation and through a lot of reading from books, journals, and online articles with the information gathered from the research methodâ€™s advisor. Quantitative methods were chosen merely to further support the analysis.
3.1.1 Qualitative Method Background study on principal of natural ventilation, from the definition and theory of natural ventilation to its mechanisms. A detailed research on the theory was conducted specifically on Malaysiaâ€™s climate dwellings.
3.2.2 Quantitative Method Details data from survey among the resident of Seri Iskandar are done and were tabulated to support the data collected in the early phase using qualitative method.
The rate of the
effectiveness of natural ventilation in terrace housing has also been collected as it represents the importance of having natural ventilation in design.
THE PHASE OF STUDY
3.2.1 Phase 1: Background Study A thorough study on the theory of Natural Ventilation was done through observation and source of income of various types of literature materials.
The study covers on the theory and
mechanisms of natural ventilation especially on Malaysiaâ€™s climate.
The quantitative method through questioners and interviews are successfully done afterwards among the residents of Seri Iskandar to support the data obtained by qualitative methods. The questioners and interviews are done among four selected housing units which were located at different area in the same residential area.
3.2.2 Phase 2 : Data Analysis The data and statistics collected was obtained by qualitative and quantitative method are then gathered. The data is collected by observing the condition of house, types of ventilation, itâ€™s orientation, and the types, location, size and shape of openings of each house. The plans of the houses picked are also obtain from the developer. Then, an interviewed is done with the owner of the house on their condition of ventilation, types of mechanical ventilation used, frequency of using mechanical system for thermal comfort, and their opinion on the efficiency of the natural ventilation system in their houses. The owner are also asked for suggestion to improve their state of existing ventilation. Some
questioner are also been handed to the occupants for further information on this research.
Using the information obtained, a comparison between these four units are done for further research. The comparison is then discussed to see which house has the best natural ventilation than the others and what is the factor affecting the result. This phase was vital as to testify the importance of natural ventilation.
3.2.3 Phase 3 : Initial Formulation This information was then further rectified into comparable diagrams, pie charts and bar charts.
3.2.4 Phase 4 :Writing Draft, progressive literature review reports and final findings were produced.
3.2.5 Phase 5 : Conclusion and Recommendations The conclusion will involve the theoretical facts and principles collected during the early phase and the final findings data to support the theory that are used and adapted in data analysis. Along with that subjects are supported with recommendation or comment of each adaptation.
CHAPTER 4: DATA COLLECTION AND FINDINGS
4. 1 BACKGROUND STUDY
Figure 11: Seri Iskandar map
A case study is done before taking any further action to helps improve the knowledge on the selected site. From the case study, it can be stated that Bandar Seri Iskandar is a town and district capital of Perak Tengah in Perak, Malaysia and it is located on the main Ipoh-Lumut highway between the old mining town of Tronoh and Bota in central Perak. The town is divided into 3 sections, which are: i.
Bandar Universiti Seri Iskandar (opposite of original settlement of Taman Maju),
ii. Taman Teknologi (SIDEC) Seri Iskandar (next to UiTM and a small industrial park) and
iii. Puncak Iskandar (next to government offices, schools and district mosque). 34
The major residential area here at Seri Iskandar includes Taman Maju, Bandar Universiti Seri Iskandar, Taman Teknologi Seri Iskandar, Puncak Seri Iskandar, Taman Gemilang, Desa Seri Iskandar, Taman Seri Iskandar Bistari, RPA Changkat Sodang, Taman Tasik Putra, and Medan Bali Emas. The area of case study however is picked randomly at Taman Teknologi Seri Iskandar.
Figure 12: Taman Teknologi Seri Iskandar
Most of the house is design based on the North-South and some are beased on East-West orientation. The houses was selected by its’ location and orientation of the building.
Besides the geographical layout, climate case study is also done for more information on the area. From what have been found, throughout the year daytime temperature generally reaches highs of round 33°C (91°F) while at night the average minimum temperature drops down around 24°C (74°F). 35
Below are the charts that plots the average high and low temperature and wind speed of Seri Iskandar throughout the year.
Figure 13: Temperature chart of Seri Iskandar.
Figure 14: Wind speed chart of Seri Iskandar.
4. 2 DATA ANALYSIS AND FINDINGS
From the background study and literature review, the efficiency of natural ventilation in terrace house in Seri Iskandar residential area can be identify. The types of ventilation mechanism from its size, and location is observed and located. The plan of the house and the positions of opening were studied.
Louvered windows Sliding window
Figure 15: Terrace house layout plan
Figure 16: Terrace house elevations
Four house was randomly selected for further studies on this subject. The four house is the compared and the data is shown as below.
Figure 17: House 1 front elevation
Figure 18: House 1 rear elevation 38
Figure 19: House 2 front elevation
Figure 20: House 2 rear elevation
Figure 21: House 3 front elevation
Figure 22: House 3 rear elevation
Figure 23: House 4 front elevation
Figure 24: House 4 rear elevation
All four houses have different building orientation even though it is located in the same residential area. Nevertheless, the orientation does not have much effect on the wind flow to the house since the area is packed and wind flowing is not so very strong.
Since the wind in this area is not very strong, the orientation plays fewer roles in term of passive design. But since the sun glare is strong in this area, a lot of houses have installed awnings and extended their front roof to help avoid the house from overheating. Many houses on the corner of the street seem to have awnings at their sides above their window as shading devises.
The terrace housing in this area is a type of low cost terrace house, hence there are slightly small and does not acquire large area. Only the corner lot house have more spacious yard and receive the most wind flow although the design is the same. Hence the lot corner can be concluded to apply the most cross ventilation in the area compared to the house in the middle of the housing.
For a more detail data analysis and findings, a few questioners form is given to the selected residents and few questions have been asked according to subject. The data was the collected and tabulated shown in Table 1.
HOUSE 1 Type
HOUSE 3 HOUSE 4
fixed louvers Window
Body level Body level Body
back, sides front,
Body level at at
size Table 1: Comparison of four selected houses
From what have been observed, most of the terrace house uses cross ventilation. The opening type used by most of the house is also basic types of openings which is doors and windows. From what have been observed, all four houses do not have sliding doors, and use sliding and louvered type of windows. The opening location is at front, back and side of the house and the opening size is average.
For house 1, a few renovation had been made at the back area, hence, the there is a slightly difference in term of the openings of the house. Whereas house two, three and four is in itsâ€™ original state. 42
Graph 1 : Occupants 6 5 4 Family (Own house) 3
Family (Renting) Students
2 1 0 House 1
Two out three of the interviewees lived among four to eight people while the other two live with less than four persons in a house. By referring to the data above, we can conclude that most of people that live in terrace house are average people with less than five children or UiTM students that rent the house.
The density of the person in the house is moderate with three to five person each house. The produced heat is not high, and the required amount of to cool each person are low. Hence the thermal comfort of the house does not affected by the number of occupants in the house since the house is not packed and suitable to live within that range.
Graph 2 : Windows Opening Frequency 25
0 House 1
Graph 2 stated that most of the house that are interviewed happened to open their windows and doors very frequent. House 1 normally open their windows and door twenty hours per day average. House 2 with the least occupant opened their window and doors ten hours average per day while house 3, eighteen hours per day. House 4 on the other hand opened their windows averagely 12 hours per day.
This shows that the natural ventilation are highly required. Since the natural ventilation is obtain by opening their windows and doors, the possibilities that natural mechanism inside the houses are functioning well is considerable. Hence we can conclude the mechanism of natural ventilation is adapted in designing terrace Seri Iskandar.
Graph 3 : Mechanical Ventilation 30 25 20 Fan 15
10 5 0 House 1
From what have been observe, most people in Seri Iskandar residents uses fans and air-conditioning systems in their houses to keep the desired level of thermal comfort. On graph 3, we can conclude all of the three houses use fan type of mechanical system to support their natural ventilation system.
House 1 operates their mechanical system the most, averagely twenty three hours daily, probably because they have the most occupants. House 2 use their mechanical system fifteen hours daily, but they have additional mechanical support like air-conditioner to help them increasing their level of thermal comfort. House 3 twenty hours daily with additional exhaust fan at the back of the house, and house 4 24hours daily, average.
Graph 4 : Spaces and Ventilation 3.5 3 2.5 2
Living Room Bedroom
1 0.5 0 House 1
Graph 4 showed a survey done by all the occupants in all of the three houses. In house 1, 2 out of five voted for bedroom as the most important space for mechanical ventilation and the other three choose bedrooms. All three occupant in House 2 on the also stated that their living room required the most mechanical system. Meanwhile in House 3, two occupants votes for the living room, one person vote for the bedroom and the other one wants more mechanical ventilation in the kitchen. In House 4, all the occupants also say that the bedroom is the space that needs mechanical ventilation in their house.
From the graph, it can be analysed that the most required mechanical ventilation system is in bedroom. This shows that in all of the terrace house at Seri Iskandar, the space with the poorest natural ventilation is the bedroom. Probably it is because cross ventilation can hardly occur in the state that only one side of the wall that have window.
All of the interviewees in each house were also asked whether the natural ventilation in each house is adequate or not. Giving the rate from one to five, one is very inadequate and five is very adequate, these were the result for the question.
Resident's Respond 0% 17% 25%
Very Inadequate Inadequate Moderate 25%
Satisfied Very Satisfied
From the pie chart above, it can be conclude that 33 percent of the occupants says that the natural ventilation was moderate, 25 percent stated that the ventilation is not enough and another 25 percent stated that it is enough. The other 17 percent of the occupants is very unsatisfied with the natural ventilation in their house. While none of them are highly satisfied with the condition.
CHAPTER 5: CONCLUSION ANN RECOMMENDATIONS
5. 1 CONCLUSION AND RECOMMENDATIONS
This case study is focused on the efficiency of natural ventilation for terrace housing in Seri Iskandar, but may also apply in other residential units of similar climate as Seri Iskandar. As a designer, an architect must understand the concept and principle of designing a sustainable shelter so that it satisfies the need of their clients.
What I have found from doing this research is that there are many options available for architects toward designing a more efficient natural ventilation in such climatic conditions. Simple strategies such as shaping the roofs, increasing the high of level, adaptation of new openings design for maximum cross ventilation can be applied to help architect to design a house. If natural ventilation system can be fully used, it will not only save the energy but also our environment. This will lead to a better future for the next generation. This research is done for guidance in designing a residential unit with better natural ventilation.
From the case study and the research done it can be conclude that the passive design of terrace housing in Seri Iskandar is satisfactory. According to the surveys and interviews, most of the residence in Seri Iskandar maximised the use of their openings for better ventilation. This shows that the design of the terrace house in Seri Iskandar comply the need of natural ventilation
improvements in the design that can help increase the level of efficiency of natural ventilation for the houses.
But since natural ventilation system is weather-dependence, the only problem is that the state of Bandar Seri Iskandar itself. The temperature here is very hot, and rarely windy. The outdoor air quality is not really good here and the air flow is not flowing at itâ€™s best since there is a lot of development going on here. For example, the new shop lot just before entrance of the residential area. Hence, it is impossible to have a perfect thermal comfort level from a fully natural ventilation system without mechanical ventilation support. It is quite impossible for all the residence in hot and humid urban area for not having any mechanical support for their ventilation.
Even though the natural state of this area is poor for a natural ventilation design to adapt, there are also few design considerations that can help improving the thermal comfort for this housing area. For example, in Seri Iskandar context, the choice of types of windows does affect the natural ventilation efficiency of the house. Using sliding windows is the best choice for window selection as it promotes view and gives maximum air flow across the living room. The use of jalousie window at the back is suitable as it helps the used air escape at the back area. Openings should be large and maximised, but must have proper shading device such as louvers and overhangs so that the amount of sun glare entering the house can be control.
Since cross ventilation might be limited, stack effect method should be fully used for a better natural ventilation system. Double roof system is preferable in terrace housing because it 49
enhance the stack effect for a better indoor air quality. Increasing the height of the ceiling also helps better cross ventilation across the house unit and adds stack effects to the design. Adding fixed louvers above the human level can also encourage the removal of hot air from the house.
The conclusions can provide useful information for architects to make a residential building with more efficient natural ventilation, energy conservation and comfortable. However, the conclusions were obtained by investigations based on weather conditions of Seri Iskandar, hence; they are effective just in those areas of similar climate as Seri Iskandar.
CHAPTER 6: REFERRENCES Books : Norbet Lechner, (2001), Heating Cooling Lighting Design Methods for Architects, Canada, John Wiley & Sons, Inc Mat Santamouris and Peter Wouters, (2006), Building Ventilation The State of Art, London, Earthscan. Hazim Awbi, (2003), Ventilation of Buildings, London, Spoon Press M. Santamouris, (2007), Advances In Passive Cooling, London, Earthscan. Abdul Malek Abdul Rahman, (2004), Low Energy Cooling Technology for Malaysian Homes, Malaysia, Penerbit Universiti Sains Malaysia. Baruch Givoni, (1994) Passive Low Energy Cooling of Buildings, United States of America, John Wiley and Sons, Inc. Mat Santamouris and D. Asimakopoulos, (1996) Passive Cooling of Buildings, London, Earthscan. Francis Allard and Matheos Santamouris, (1998) Natural Ventilation in Buildings: A Design Handbook, London, Earthscan.
Journal : Chalermwat Tantasavadi et. al., (2007), Evaluation and Design of Natural Ventilation for Houses in Thailand, Journal of Architectural/Planning Research and Studies, Volume 5. Issues 1. P 85-98 Wang Liping and Wong Nyuk Hien, (2007), Applying Natural Ventilation for Thermal Comfort in Residential Building in Singapore, Architectural Science Review, Volume 50.3, p 224-233
Guohui Gan (2010), Interaction Between Wind and Buoyancy Effects in Natural Ventilation of Buildings, The Open Construction and Building Technology Journal, Volume 4, p 134-145 S. Barrington, N. Zemanchik and Y. Choiniere (1994), Orienting Livestock Shelters To Optimize Natural Summer Ventilation, American Society of Agricultural Engineers, Volume 37, no. 1, p 251-255 Givoni, B. (1992), Comfort Climate Analysis & Building Design Guidelines, Energy and Buildings, Volume 18, no. 1, p. 11-23 Nedhal Ahmed M. Al-Tamimi et. al, (2010) The Effects of Orientation, Ventilation, and Varied WWR on the Thermal Performance of Residential Rooms in the Tropics, Journal of Sustainable Development, Volume 4, No.2, p 142-149 Mazran Ismail & Abdul Malek Abdul Rahman, 2012, Stack Ventilation Strategies In Architectural Context: A Brief Review Of Historical Development, Current Trends And Future Possibilities, Volume 11, Issues 2, p 291-301
Thesis : Luiz Busato, (2003), Passive Cooling and Energy Efficiency Strategies for Design of Hotel on the Southern Coast of Pernambuco, Brazil, thesis London Metropolitan University Cai Feng Gao and Wai Ling Lee, (2010) Influence of Window Types on Natural Ventilation of Residential Buildings in Hong Kong, Department of Building Services Engineering, thesis, Hong Kong Polytechnic University Tine Steen Larsen, (2006) Natural Ventilation Driven by Wind and Temperature Difference, PhD thesis, Aalborg University
R.M.J. Bokel, ( 2007) The Effect of Window Position And Window Size On The Energy Demand For Heating, Cooling And Electric Lighting, Department of Architecture, thesis, Delft Technical Universtiy. Jan P. Jensen, (2004) True Openings in Wind Driven Natural Ventilation, Department of Building Technology and Structural Engineering, PhD thesis, Aalborg University
Websites : Natural ventilation: cross ventilation can be reach at http://www.architecture.com/SustainabilityHub/Designstrategies/Air/ 1-2-1-3-naturalventilation-crossventilation.aspx (12.4.2012) Natural ventilation: stack ventilation can be reach at http://www.architecture.com/SustainabilityHub/Designstrategies/Air/ 1-2-1-2-Naturalventilation-stackventilation.aspx (2.5.2012) Natural ventilation can be reach at http://www.arch.hku.hk/teaching/lectures/airvent/index.html (2.5.2012) Principle of Natural Ventilation can be reach at http://gse.cat.org.uk/cpd/pluginfile.php/21/mod_resource/content/1/A irtightness%20and%20ventilation.PDF Natural ventilation can be reach at http://en.wikipedia.org/wiki/Natural_ventilation (5.5.2012) Ventilation (architecture) can be reach at http://en.wikipedia.org/wiki/Ventilation_(architecture) (5.5.2012)
CHAPTER 7: APPENDIX Observation
1.Type of ventilation used a) Cross Ventilation b) Stack Effect c) Both
2.Opening types, how many a) Doors (.........) b) Windows (.....) c) Others (.....)
3.Window Types a) Sliding b) Side hung c) Louvered
4.Opening Location a) Body level ( Front / Back / Sides ) b) Upper level ( Front / Back / Sides ) c) Lower level ( Front / Back / Sides )
5.Opening Size a) Average b) Big c) Small
Questions fo interview
1. How many occupants live in the house? Please state :.....................
2. Occupants are : a) Families (own the house) b) Families (Renting) c) Students (Renting)
2. Frequency of opening windows/doors per day ................... hours average
3. Windows/doors are often opened at a) Day b) Night C) Both
4. The main reason why they open windows a) Ventilation b) Lighting c) Others (please state :............................)
5. The main reason why they do not open windows a) No one in the house b) Noise c) Pollution d) Temperature (too hot/too cold) e) Safety
6. What are the type of mechanical ventilation did you use? a) Fan b) Air-Conditioner c) Others (please state :............................)
7. Spaces that most needs mechanical supports a) Living Room b) Bedroom c) Kitchen
8. Frequency and duration using air-conditioner everyday ................... hours average
9. Frequency and duration using ceiling fan everyday ................... hours average
10. Is natural ventilation in the house is adequate? If not, what did you propose to overcome this problem? ______________________________________________________ ____________________________________