Name of module : Building Services 1

Module code : BLD 60304

Title : Ventilation Problem in Heritage Building

Submission Date : 23rd November 2015

Name of lecturer : Miss Lim Tze Shwan

Name of group memebers : Mok Po Yi (0318207)

Ng Wai Khong (0317980)

Lee Ern Hui (0319703)

Hiew Li Ming (0319941)

Lim Chuning (0320369)

Lee Jian Ru (0318132)

Introduction1 | P a g e

Ventilation is the process of changing air to the outside as well as circulation of air

within an enclosed space. Ventilation in a building has fundamental function. The main

function of ventilation is to maintain the air purity of an enclosed space. For example,

preservation of oxygen content, removal of carbon dioxide, control of humidity, removal of

pollutant gas and etc. Ventilation system had been found out since ancient time. Back to

past, when human brought fire into his shelter, human had discovered the need to have a

opening to let oxygen in for supplying gas for the combustion and respiration while let the

smoke out. This is the basic concept of ventilation.

There are two types of ventilation which are natural ventilation and mechanical

ventilation. Natural ventilation is a ventilation system which relies on wind and thermal

buoyancy as natural driving forces. According to the history, human has already used this

driving forces to create an ideal thermal environment and remove the contaminants from the

building. Natural ventilation requires a good relationship between the building structure and

the system itself. Thus, the structure and design of heritage building is one of the influence

for the ventilation.

There are three principles of ventilations which used to utilize the natural driving forces

to ventilate a space. The principles included single-sided ventilation, cross ventilation and

stack ventilation. Firstly, single-sided ventilation (figure1.1) relies on only one side opening.

Typically, room with openable windows on one side and closed internal door has fully applied

this ventilation principle. The ventilation is promoted by the buoyancy effect depends on the

difference of temperature between the space in exterior and interior, vertical distance

between the opening as well as the area of opening. Besides, cross ventilation (figure 1.2)

allows air flows between two sides of a building. In fact, air will enter and leave through

windows, hatches or grills which intergrated in the facades. For example, open plan office

landscape. However, there is a limit to the depth of a space that can be effectively cross-

ventilated in a building. In addition, stack ventilation (figure 1.3) is drving force which

promote an outflow from the building to let fresh air enter thru openings at a lower level to

higher level. For example, building with an elevated central part, warm air rises to be

exhausted through openings such as wind tower which is located on the roof or top of the

building. Stack ventilation requires certain height between the air outlet and air inlet..

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Figure1.1 single sided ventilation Figure 1.2 cross ventilation

Figure 1.3 stack ventilation

For mechanical ventilation, it is the ventilation provided by electrical fans which oftens

be a part of air conditioning system to provide the artificial airflow supply. This kind of

ventilation required energy to generate the machines in the building. In fact, for heritage

building, mechanical ventilation might not be commonly used because the technologies has

not been modified in past and the installation fees might be high so people in past would

choose natural ventilation instead.

In this report, by studying a case study, we can find out the importance of ventilation in

a historical building and understand the traditional way to work out the ventilation system in

an enclosed space. Besides, we would study on the problems and benefits of the particular

ventilation and also way to improve the ventilation system in the heritage building while

conserving the unique part of it.

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History

There are several heritage buildings in Malaysia. In this research, we chose one of

the UNESCO World Heritage Site in George Town, Penang which is City Hall. City Hall is

municipal building in George Town, Penang and it was constructed in 1903 and opened in

1906 as the seat of Penang Government. This building is appointed as a national memorial

hall by the Antiquities Act of 1982 and as a Category 1 building.

City Hall, George Town, Penang

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Application

Natural ventilation is the process of driving in fresh air through an enclosed space by

natural means which means without the use of any mechanical system such as fans. There

are basically two types of natural ventilation system that can be utilized in a building which

are wind driven ventilation and ventilation affected by stack effect. Both of these ventilation

are affected by pressure differences which occur naturally. Wind driven ventilation caused by

pressure variations is produced by the natural forces of wind while stack ventilation is

caused by pressure generated due to differences in temperature between outdoor and

indoor of the building.

Ventilation caused by pressure variations due to wind movement occurs when the

wind blows across a building. The wind hits the windward wall to cause a positive pressure

and leave the leeward wall to cause negative pressure which is also known as suction.

Therefore, infiltration and ex-filtration air will occur. Infiltration air is the uncontrolled entry of

outdoor air into an enclosure through cracks or any openings due to pressure differences

between inside and outside where as ex-filtration air is the flow of indoor air from an

enclosure to outdoors. The air enters and leaves the enclosure through openings to provide

balance and relieves the pressure on the walls.

In this wind driven ventilation system, to provide ventilation and capture the wind, the

shape of the building acts as an important factor. The shape of a building helps in creating

wind pressure that can drive the air flow through openings provided in the building such as

windows and doors. Moreover, there are many other factors that plays a big role in design

guidelines for different buildings. For example, to maximize the ventilation, location with a lot

of wind should be chosen so that the windward wall is perpendicular to the wind.

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Besides, Infiltration and ex-filtration can occur when there is difference in temperature

caused by weather. Infiltration usually occurs mainly during winter as the air outside is

colder. Colder air is heavier than the air outside which is hotter and less dense. In high-rise

buildings the stack effect also causes infiltration where the outdoor air enters the enclosed

building or space. In contrast, ex-filtration occurs during summer where the flow of indoor air

from a building to the outdoors. In summer, the air outside is hotter while the air inside in

colder. Therefore, the direction of natural air flow is from the inside to outside since the air

inside is colder and much denser.

One of the factor which causes ventilation is the stack effect of warm air rising within

a building, while cooler air exists outside replaces it. Stack ventilation is affected by the

difference between the temperature. In this ventilation system, warm air is less dense while

cool air is denser, therefore warm air in the building rises, the cooler air enters from any

openings below and replaces the warm air.

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Other than that, there is also another system known as Passive Stack Ventilation

(PSV). This system involves the combination of the air flowing over the roof and the natural

buoyancy of warm air to lift up the moist air from the kitchen, bathroom and others to the roof

ridge level where the air escapes into the atmosphere and then fresh air enters into the

building through trickle vents or passages in the windows and doors to replace it. PSV

system is energy efficient therefore it can work without the need for any electrical fans or

control. The ventilation depends on the amount of movement of external air and

temperature. Both wind and stack driven ventilation is important as a natural ventilation

system, design for natural ventilation should therefore incorporate to maximize design

concepts of both for better air flow and energy efficient system.

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Installation

Over a century of history, Penang City Hall which located at Georgetown had applied

the basic natural ventilation system to cope with the weather of Malaysia which is always in

a state of hot, humid and rainy condition. Unlike countries which undergoes four seasons,

the City Hall which is built in Malaysia takes the least concern for Infiltration Air and

Exfiltration Air in both internal and external of the building over the year. Moreover,

Georgetown, Penang is located on an island which also approved the needs for natural

ventilation which is affected by pressure variation due to wind and stack effects.

While, for the natural ventilation to be more effective, there must be adequate of

ventilation at every divisions and rooms in the particular building although the wind doesn’t

prevail to any of the direction surrounding the buildings. As in the diagram above, openings

like doors, windows and small air window is installed at every faces of direction of the

building. Hence, the building was placed on an urban space or land where the inlets and

outlets of the building are not obstructed by any object which will effects the wind to flow into

the building. Furthermore, vertical shafts and open staircases were installed in advance to

generate stack effects.

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Beside the hall inside the building, all the divisions and rooms are installed and

designated narrowly to allow natural ventilation to be effective, because it is difficult to

distribute fresh and healthy air to every portion of the buildings if the space of each particular

room is wide by using natural ventilation. Mostly of the rooms have more than 2 or more

separated supply and exhaust openings, the windows openings must be operable by the

occupants, so that the ventilation can be effective.

When the wind or air flow into the building, it will creates a recycle, refresh and

rejuvenate in the process of maintain the ventilation inside the building always fresh and

establish hazard-free internal air quality. Openings will be installed at the top of the buildings

or roofs to circulate the air from the inside to the outside in the process of Infiltration and

Exfiltration of Air. This is crucial due to the different temperature of surrounding in the

morning and night time. So, the requirement of the ventilation in the building should be

balance in terms of temperature no matter in the morning or night time.

Installing opening above the door takes an important role for wind and stack effect to

be more productive because the doors located at the outside will not be opened 24 hours in

terms of security and safety for the building. Hence, the help of the opening above the door

ensures fresh air to enter the building without the usage of the doors. Based on the diagram,

the door should be left opened at the outside during day time and door placed indoor should

be opened to receive fully circulate air for the whole building regarding the rooms and

division.

An open-building approach works well in warm and humid areas especially in

Malaysia, because the temperature doesn’t change much in the daytime and nighttime.

Therefore, daytime cross-ventilation is encourage to maintain the indoor air quality and

temperature equivalent to the outdoor temperature.

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Advantages and Disadvantages

There are two types of ventilation system found in City Hall, Penang which are

mechanical ventilation such as fans and air conditioners and natural ventilation which are the

openings of a building. As everything is in the world, there are advantages and

disadvantages for both type of ventilation system.

First and foremost, my group has decided to look into mechanical ventilators. City

Hall, Penang possess two types of mechanical ventilators which are fans and air

conditioners. For starters, there are several advantages for using a fan on a day to day basis

as City Hall is now an office building. One of the main advantage of having a fan as a

mechanical ventilator is that ceiling fans can keep the people in the room cool. A ceiling fan

pushes air downwards which helps create a breeze that helps the person to cool their skin

through evaporation, this can keep the workers who are using City Hall as an office to stay

cool twenty four hours a day. Besides that, unlike the air conditioner, a ceiling fan does not

use a lot of electrical energy hence, it saves money and energy. A ceiling fan requires the

same amount of energy to function as needed by a standard 100W light bulb. Strategically

locating a ceiling can provide ample amount of cool air to a room which can reduce the

usage of air conditioners which in turn can save large amount of energy.

The disadvantage of ceiling fans are that they are noisy at times. This usually

happens when the rotators lose the greasiness which will cause an unpleasant sound. This

will create an unsettling environment especially for a work place which should be peaceful

and calm. This means rotatory maintenance is needed for fans. In addition, ceiling fans are

difficult to clean as you are required to climb up a ladder to clean it. If the fan is not cleaned

regularly, layers of mould and dust will be formed on the blades of the fan which will cause

some discomfort if used. In this case, this disadvantage will be emphasized on as the ceiling

fans were not properly cleaned for the office use (refer to figure 3)

Secondly, the other mechanical ventilators present in the building is an air

conditioner. The advantage of using an air conditioner is that it creates a very clean and

germ free atmosphere. This is because air conditioners are capable of filtering out pollen,

dusts and allergens which could cause discomfort in the room. This is very useful if it is used

in an office building such as City Hall, Penang as it can disinfect the air we breathe which

creates a friendly environment especially for workers who have asthma. As for the

disadvantage of using air conditioning, it is very costly and hazardous to the environment. It

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is expensive to use the air conditioner as it uses a lot of electricity. Since it uses so much

electricity, large amount of coal has to be burnt to produce more energy to power the device

which causes a large production of carbon dioxide which promotes the greenhouse gases

which leads to global warming.

Last but not least, natural ventilators are found in City Hall as well which are the

opening found in the building such as windows and doors. The advantage of natural

ventilators is that they are lower in cost. It is cost free because natural ventilation relies on

wind to provide the cool air into the building. Since it dependant on the movement of the

wind, it can help replenish fresh air into the building which can improve the air quality in the

building. The disadvantage of natural ventilation is that it is unsuitable for noisy and

clustered areas. This is because noise will enter the building through the openings which will

cause disruption in the quiet environment of a place. It is also not suitable for places which

are clustered which is strongly related to our case study regarding City Hall as we

discovered that there are the presence of obstructing objects around the openings the

building which disrupts the flow of wind or fresh air into the building . This is major problem

as it does not make the natural ventilation as effective as it should be.

In conclusion, both type of ventilation system brings their own set of pros and

cons. Which is why most people require both type of ventilation system as the 2 different

ventilation system complements each other but both carry the same purpose and that is too

provide a cool and allergen free environment for the user.

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Ventilation Problems in City Hall City Hall is located at the north end of Penang Island. It is located by the sea and

results in the effect of ground water level and salinity. These conditions occur the cause of

deterioration in heritage building due to uncontrolled moisture problem. If untreated, it can

led to dampness, rotting, molding and destruction of materials, finishes and building

structures. Besides that, the growth of fungi and other microbial agents due to uncontrolled

moisture will degrade the indoor air quality.

Figure 1

Besides the moisture problem, salt crystallization also contributes to the freshness of

indoor air quality. Salt weathering is related to moisture problem. It results in the breakdown

of surface materials such as concrete. Different building materials have different salinity

values. Modern porous building materials such as Portland cement contained a high content

of salinity value which is sodium chloride. The salt that remains on the surface of concrete

wall leads to the occurrence of salt weathering after the moisture is evaporated. After time,

materials decay by abrasion,

erosion, crumbling and loss of

the surface.

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Figure 2

Another pollutant is dust. Dust Mites are a species that prefer warm and humid

climate. Dust is generally found on the floor, corner or other surfaces. For this building, we

found that it is mostly accumulated in the mechanical ventilation system such as air

conditioner diffusers and fan and architectural structures such as cornices. When a person

inhales too much of dust, the enzymes that contained in dust can kill cells within the human

body. It is not only degrade the indoor air quality, it will also affect one’s health.

Figure 3

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Recommendations After conducting our research on Town Hall, Penang, we have discovered that the

ventilation system as well as air quality in this heritage building was deemed unacceptable

and we then furthered our research to pinpoint the problems that causes the poor indoor air

quality and we have made several recommendation to improve the ventilation system in this

building.

First and foremost, one of the main problem discovered which caused the building to

have poor air quality is due to the fact the mechanical ventilation systems were not properly

cleaned nor maintained throughout its’ reuse as an office building as observed from diagram

1 and 2. Therefore, one of the methods to improve the air quality in Town Hall, Penang is by

giving regular maintenance for the mechanical ventilation present in this building. The

pictures gathered on the mechanical ventilation in Town Hall, Penang proves that they did

not clean the fans and the air conditioners for a period of time as layers of dust and mould

have already been laid on the fans and air conditioners. Hence, to improve the ventilation in

Town Hall, Penang, the mechanical ventilators should be regularly cleaned to allow the

ventilators to operate smoothly and efficiently.

Diagram (1) and (2)

Besides that, my group noticed the presence of local obstructing objects preventing

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the wind from entering into the building. This sort of circumstances will reduce the natural

ventilation of a building as fresh air cannot properly enter the opening of the building. It was

observed that the buildings and trees located nearby this heritage building have blocked the

path of the prevailing wind direction. To overcome this predicament, we suggest to build

include architectural elements such as wingwall or parapets which can help redirect the

direction of the prevailing wind into the openings. This can not only help improve the

ventilation but it can help save the cost of the building. This is because they do not have to

rely solely on the mechanical ventilators as much if the natural ventilation of this building

improves.

Furthermore, this heritage building has been reused as an office building. Like every

other office buildings, there are the presence of machines such as computers and printing

machines which increases the temperature of the building and emits harmful chemicals to

the office workers. In addition, the building has a high percentage of humidity and moisture,

this means that the restrooms are not properly ventilated which can cause the environment

of the building to feel uncomfortable. Exhaust Ventilation system should be install in this

building to overcome this problem. The function of exhaust ventilation system is to ventilate

the harmful fumes, excess heat and moisture content from the building. The target areas for

these exhaust ventilators are to be placed at the printing room which emits harmful gases

such as ozone and generates large amount of heat and as well as the wet rooms such as

restrooms found in the building. With the presence of the exhaust ventilators nearby these

areas, the air quality of the building will drastically improve as the unwanted chemicals and

bacteria in the air will be quickly removed and will be replaced with fresh air.

Last but not least, solar chimneys should be installed in this building to improve the

natural ventilation of the building. A solar chimney carries the function of regular chimney but

is powered by solar energy. The solar chimney will increase the heat of the air on top of the

roof. This will cause the hot air to exit the building due to the pressure difference and the

cold air below it will rush in to take its’ place and the process is repeated. This greatly

improves the natural ventilation of the building and helps replenish the indoor air which can

help remove harmful bacteria and dust from the surrounding environment. Diagram 3 shows

an example of how a solar chimney works when installed into a building.

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Diagram (3)

In a nutshell, these are one of the few recommendations to improve the ventilation

system in Town Hall, Penang with hope that these recommendations can improve the air

quality of this heritage building to ensure that this building can be reused and preserved for

many years to come.

Conclusion

In the nutshell, ventilation for a particular building is keen important in preserving the thermal

comfort, healthy and fresh recycle of air quality in the indoor of a building and available the building to be

more sustainable. Both natural and mechanial ventilation works as a chemistry together to strengthen

and improve the indoor air quality of the heritage building, so the building can be preserved, used as an

economical profit to the country (tourist spot) and to bring down another few hundred years for the future

generations because these heritage buildings symbolize an occurance happened on the past like our

building were once built by the British when we are under control by Britain in the 90’s.

Through the case studies we examined, observed and investigate, it doesn’t only tell us about how

important the ventilation is, the factors and also the effects of both natural and mechanical ventilation. It

also teaches us on how to apply these ventilation system to our own building and how to advise people

on installing these mechanical ventilations in their respective building because these knowledge will bring

us and assist us especially after we graduated and enroll in the construction field. Hence, in the future,

we will be able to be assign and handle with more task and job which are related to ventilation.

Furthermore, our group mates had contributed each topic in order to complete this report. By using

the knowledge that the lecturer taught in class about ventilation and also a bit of finding in the library and

referencing through online, we are able to present a completely filled report of our topic. This required

good co-operation between group mates and also appreciate the guidance, ideas and opinions

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contributed by our class lecturer to avoid putting false information and knowledge about ventilation in this

report.

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Citation

1.) Prihatmanti, R., & Bahauddin, A. (2014). Retrieved October 16, 2015, from http://web.usm.my/jcdc/vol19_1_2014/JCDC 19(1) 2014-Art. 5 (69-91).pdf

2.) Natural Ventilation Explained. (2010). Retrieved October 19, 2015, from http://www.breathingbuildings.com/products/natural-ventilation-explained

3.) Walker, A. (2014, April 11). Natural Ventilation. Retrieved October 19, 2015, from https://www.wbdg.org/resources/naturalventilation.php

4.) Mechanical Ventilation. (n.d.). Retrieved October 21, 2015, from http://new-learn.info/packages/clear/thermal/buildings/active_systems/mv/index.html

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