2. Introduction
Ventilation strategies
Natural ventilation
Types of Natural Ventilation Openings
Cooling sensation from airflow
Wind-driven cross ventilation
Buoyancy-driven stack ventilation
Underfloor air distribution (UFAD)
Breathing building
Wind Turbo Roof Air Ventilator
Conclusion
References
5/9/2015
2
3. Ventilation strategies
Natural ventilation
flow driven by wind and temperature
Forced air – mechanical ventilation
fan-driven through ducts
Traditional HVAC
mechanical cooling, overhead distribution
Unconventional HVAC
mechanical cooling, unconventional distribution
Hybrid ventilation
combinations of the above systems
5/9/2015
3
4. Natural Ventilation
Ventilation driven by natural pressure forces
• wind
• buoyancy - due to temperature differences; the ‘stack effect’
The ventilation of indoor environments is also necessary to maintain
the required levels of oxygen and air quality in a space.
For breathing and general fresh air require about 10 ls-1 per person
5/9/2015
4
5. Types of Natural Ventilation
Openings
Windows :
Windows sliding vertically, sliding horizontally, tilting,
swinging
Doors, monitor openings and skylights.
Roof Ventilators (weather proof air outlet).
Stacks connecting to registers
Specially designed inlet or outlet openings.
5/9/2015
5
6. Cooling sensation from airflow
0
2
4
6
8
10
0 0.5 1 1.5 2 2.5 3 3.5
Airflow (m/s)
Coolingsensationdeg.C
Source: Natural Ventilation in Buildings, Tony Rofail,
NEERG seminar, 31 Aug 2006, Windtech Consultants
5/9/2015
6
7. Wind-driven cross ventilation
Wind-driven cross ventilation occurs via ventilation
openings on opposite sides of an enclosed space.
The building floor span depth in the direction of the
ventilation flow must be limited to effectively
remove the heat and pollutants from the space by
typical driving forces.
5/9/2015
7
9. Buoyancy-driven stack ventilation
Buoyancy-driven stack ventilation or displacement ventilation (DV)
relies on density differences to draw cool, outdoor air in at low
ventilation openings and exhausts
A chimney or atrium is frequently used to generate sufficient
buoyancy forces to achieve the needed flow.
5/9/2015
9
12. Underfloor air distribution
(UFAD)[3]
Underfloor air distribution (UFAD) is an air distribution
strategy for providing ventilation and space conditioning in
buildings as part of the design of an HVAC system.
UFAD systems use an underfloor supply plenum located
between the structural concrete slab and a raised
floor system to supply conditioned air through
floor diffusers directly into the occupied zone of the
building.
5/9/2015
12
15. Wind Turbo Roof Air Ventilator[2]
5/9/2015
15
It spins with the slightest breeze, creating
an upward draft which draws hot air,
odor, smokes, dampness and other
pollutant particles upwards.
Creat invisible convection current, and in
the process extract them together with
pollutant particles, which has become
hot due to the buildings exposure to long
hours of sunlight and manufacturing
processes and due to other pollutants
particles within the building.
16. Contd..[3]
5/9/2015
16
As the stale and hot air is extracted by the Air
ventilators, it is replaced by fresh air at ambient
temperature entering through the natural openings
18. Conclusion
Low cost
Easy installation
Protect from high heating
No water leakage
Anti-corrosion, anti-acids and bases, anti-oxidation
Light weight
Long use
5/9/2015
18