Principles of ventilation for parking lots (Parking Garage Ventilation)

Drawings actually used by engineers, covering design principles, ACH values, air volume,

CO Control, Pressurization, and calculation examples

🔵 1) The main purpose of parking lot ventilation
1. Reduce the concentration of toxic gases.
• CO (Carbon Monoxide) from automobile exhaust.
• NOx (especially in diesel cars)
2. Prevents smoke accumulation in the event of a fire.
3. Control temperature and air circulation.
4. Maintain the comfort of building users.

Main standards referenced:
•
•
• Local Code (Thai building law)

🔵 2) Types of ventilation used in parking lots.
A) Mechanical Ventilation — air duct system + suction/blowing fan

Advantages
✔ Can control the wind direction
✔ Supports large buildings

Disadvantages
✘ Many pipes
✘ Electricity costs are higher.

😎 Jet Fan Ventilation — system without pipes
Use a Jet Fan to blow air horizontally to the air suction point.
Advantages
✔ Reduce pipe work 90%
✔ Wind spreads throughout the area.
✔ Save energy

Disadvantages
✘ Must design CFD
✘ The price of the Jet Fan is high.

🔵 3) Required ventilation rate value (according to standard)
• 0.75 CFM/ft² (≈ 13.5 L/s·m²) or
• 6–10 ACH for Mechanical Ventilation
• 3 ACH (min) when there is a CO Control system

: Standard for Parking Structures specify that
• Enclosed Garage = 4–6 ACH
• Use the CO Sensor to turn on the fan according to the CO level.

🔵 4) CO Sensor control system (Demand-Control Ventilation)
to save energy The fan will operate according to the CO level.
CO level control command
< 25 ppm turn off fan
25–50 ppm fan running low (50%)
50–100 ppm high working fan (100%)
> 100 ppm notification + fully working

Advantages of CO-Based Control
✔ Reduce energy consumption 40–60%
✔ Extends fan life
✔ Fresh air all the time

🔵 5) Principles of air flow analysis in parking lots.
1. Fresh Air must enter from one side.
2. The exhaust fan (Exhaust Fan) must be on the opposite side.
3. There must be no “Dead Air Zone” Areas where the wind does not move, such as blind corners.
4. Avoid whirling wind (Short Circuiting). Fans facing each other → Reduced efficiency.
5. Air should move at least 0.5–1.0 m/s.

🔵 6) Simple way to calculate air volume (ACH Method) Assume:
• Area = 40 × 30 m = 1,200 m²
• Height = 3 m
• ACH Value = 6 ACH (according to ASHRAE)

1) Volume = 1,200 × 3 = 3,600 m³
2) Total air volume = Volume × ACH
= 3,600 × 6
= 21,600 m³/hr

Convert to CFM (if desired)
1 m³/hr = 0.5886 CFM
→ 12,715 CFM

3) Number of fans
If using a fan 10,000 m³/hr (suction direction)
Number of fans = 21,600 ÷ 10,000 = 2.16 → Use 3

🔵 7) Fan placement principles (Layout)
✔ Exhaust Fan installed on a high wall ~2.5 m
✔ Fresh Air Intake opposite side
✔ Jet Fan mounted on the ceiling, blowing air to the suction point.
✔ The area under the beam must not obstruct the wind direction.

🔵 😎 Special requirements for fire cases
According :
• Must be able to vent smoke (Smoke Control).
• The fan electrical circuit must be separated into Fire Mode.
• Jet Fan must withstand heat 250°C – 300°C (2 hours)