TASKPropose an appropriate ventilation system of

new hypermarket mall on a very congested underground transportation tunnel

Re-establish the ventilation system by considering the existing underground facilities

FACTS1) Hypermarket mall at UK

2) Re-establish ventilation system

3) Congested underground transportation

IDEA1) UK climate

2) Upgrade ventilation system

3) Eco-friendly system

LEARNING ISSUE1) Fundamental theory of ventilation

2) How to circulate fresh air

3) Theory air change

MECHANICAL VENTILATION

Importance of mechanical ventilation

• To get enough air – quality and quantity• To control ventilation systems• To control environment air – air velocity,

location, way of use• To remove heat and dirty air

4 types of whole-house mechanical

ventilation system:• Exhaust system

• Supply system

• Balanced system

• Plenum system

SUPPLY SYSTEM• Slightly pressurizes a house by drawing

outdoor air into the house• This pressurization pushes indoor air through

small openings in the building• Hence, preventing outside moisture and

pollutants from getting in • Also protects against back drafting or backflow

of polluted air/moisture flow

Supply rich mode• Raising the air supply maintains proper room

pressure• This prevent back-flow of toilet/kitchen odors

or moisture inflow• Eg: In an office

Mechanical Air Supply with Natural

Air Exhaust• Overpressure in building occurs when air

supply is controlled mechanically and air exhaust takes place on a natural way by ventilation openings

• To prevent drought:Place air supply as high as possibleAir inlet grid must be regulated

• By preheating incoming air, drought problems can be decreased

• The ventilator controls air supply and outdoor air is transported into the building

• In supply system, a fan pulls outside air into the house, creating positive pressure

EXHAUST SYSTEM• Consist of single fan that is located in a

hallway or top of stairs

• Function: To ventilate the whole house

• Raising exhaust air decreases room pressure to prevent leaking of odors or floating bacteria into other rooms

Natural Air Supply with Mechanical Air

Exhaust• A popular form of ventilation in residential

buildings and offices

• The system is less dependent on the whether than fully natural ventilation

• The under pressure creates a pressure difference, so air is suck in

• However, a high wind pressure or temp. difference can result in drought problems

• To prevent drought, air supply openings must be placed as high as possible

• In residential: suction takes place at the kitchen, bathroom and toilet

• In non-residential: suction takes place from corridor

• An exhaust ventilation system typically consists of 1 fan and an outlet vent but may consists of a remote fan