Building Services I :Ventilation problem in heritage building

Group member: Mok Po Yi (0318207) Ng Wai Khong (0317980) Lee Ern Hui (0319703) Hiew Li Ming (0319941) Lim Chuning (0320369) Lee Jian Ru (0318132)

Introduction

• What is ventilation ?• Ventilation is the process of changing air to the outside and circulation of air

within an enclosed space• Back to past, when human brought fire into their shelter, they discovered that

the need to have an opening to let oxygen in and carbon dioxide and unwanted gases out .

• Function of ventilation• maintain the air purity of an enclosed space. Examples :

• preservation of oxygen content• Removal of carbon dioxide• Control of humidity• Removal of pollutant gas and air, etc.

• Types of ventilation • Natural ventilation• Mechanical ventilation

Natural ventilation• Ventilation system which relies on wind and thermal buoyancy

as natural driving forces

• Natural ventilation requires a good relationship between the building structure and the system itself

• 3 ventilation principles : • Single-sided ventilation• Cross ventilation• Stack ventilation.

Single-sided ventilation : relies on only one side opening

Cross ventilation : allows air flows between two sides of a building

Stack ventilation : driving force which promote an outflow from the building to let fresh air enter thru openings at a lower level to higher level

Mechanical ventilation• electrical fans which are often part of air conditioning system

to provide the artificial airflow supply.

• required energy to generate the machines in the building

CASE STUDYCITY HALL, PENANG

• Located at George Town, the north of Penang Island.• Municipal Building.• Constructed in 1903 and opened in 1906.• Appointed as a national memorial hall by the Antiquities

Act of 1982 and as a Category 1 building.

Application

Natural ventilation system

Definition • The process of driving in fresh air through an enclosed

space by natural means (without the use of any mechanical system such as fans)

Types of systemWind driven ventilation - pressure variations is produced by the natural forces of

wind

Ventilation caused by stack effect - pressure generated due to differences in temperature

between outdoor and indoor of the building.

Wind driven ventilation

•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. •Infiltration and ex-filtration occur.

Stack ventilation• affected by the difference between the temperature• warm air - less dense while cool air – denser• warm air rises within a building, while cooler air exists

outside enters from any openings and replaces it.

Installation ProcessCity Hall, GeorgeTown Penang

Installation process

Installation processNatural ventilation• The room are designated and installed

narrowly to allow natural ventilation to be effective.

• More fresh air will be distributed.• Most of the room have more than 2

separated supply and exhaust openings.• Windows are also operable by the

occupants.

Installation process

Results: The building should remain the same temperature to reach thermal comfort.

Installation process• Installing opening above the doors

important role of wind and stack effect.• Opening above the door ensures fresh air to

enter the building without usage of the doors.

• The door is left open during working hours or day time.

• Receive full circulate air of the whole building,

Advantages and Disadvantages

Mechanical ventilation

AdvantagesFan• Keep the room in a comfortable condition• Does not required a lot of energy

Air Conditioner• Provide very clean and germ free atmosphere

DisadvantagesFan• Noisy at times• Difficult to be cleaned

Air Conditioner• Costly

Natural Ventilation

Advantages• Lower in cost

Disadvantages• Unsuitable for noisy and clustered areas

Ventilation problems in City Hall

Moisture Problem Located by the sea Results in the effect of ground water level and

salinity Leads to uncontrolled moisture problem. Dampness, rotting, molding and destruction of materials, finishes

and building structures. Growth of microbial agents like fungi will degrade indoor air quality.

Salt Crystallisation Degrade the freshness of indoor air quality. Salt weathering moisture problem. Breakdown the surface of materials. Different materials have different salinity values. Materials decay by abrasion, erosion, crumbling and loss

of the surface after times.

Example : Concrete Wall• Portland cement has high salinity value which is Sodium

Chloride.• After the moisture is evaporated, the salt remains on the

surface of concrete wall Salt Weathering.

Dust Dust Mites prefers warm and humid climate. Generally found on the floor, corner or other surfaces. Degrade indoor air quality. Enzymes that contained in dust can kill cells within the human body. When a person inhales too much of dust affect one’s health. For this building mostly accumulated in air conditioner diffusers ,

fan and cornices.

Recommendations to improve the ventilation in Town Hall, Penang

Recommendation• Clean the mechanical ventilators present in the building

Recommendation• Construct a wind wall to redirect the path of the

prevailing wind direction to the openings

Recommendation• Install exhaust ventilators to remove excess heat

Recommendation• Install solar chimneys

Thank you