Using Jet Fans for Underground Parking Ventilation

The development of high-rise hotels & condominiums in urban areas due to space constraints has led to an increase in the number of underground parking garage spaces in cities. Unfortunately, maintaining good air quality in underground or enclosed parking garages has proven to be a challenging task. As a result, most underground parking garages are either under-ventilated or have difficulties maintaining clearances between vehicles and the ceiling as they’re often designed with low ceiling heights.

On the bright side, there is now a new innovative ventilation design concept for garages that reduces the height of these facilities by about 4 ft; Jet fan systems! That’s right! The use of jet fans is a great way to provide adequate ventilation in underground & enclosed parking garages.

In this post, we’ll take you through some notable benefits of using this innovative approach in the ventilation design for your underground parking garage in California. First, let’s look at some of the challenges associated with traditional ducted garage ventilation design!

Challenges of traditional parking garage ventilation

There are several challenges to maintaining adequate ventilation and good air quality in underground/ enclosed parking spaces using traditional ducted systems. 

To start, most underground parking garages in the United States use traditional ducted ventilation systems, with fresh air levels based on a predetermined number of air changes per hour. In short, they use exhaust & supply fans connected to ductwork for air distribution. In addition, the air supply is uncontrolled and extracted through the ducts, leading to poor pollution control.

Secondly, traditional ducted garage ventilation systems are run constantly, even when there are low traffic or ventilation requirements. This leads to a significant increase in the day-to-day costs of running the ventilation system.

Moreover, ducted ventilation systems don’t provide smoke or fire isolation capability. Instead, only about 50% of ducts in traditional ventilation systems can extract smoke at high levels.

Other challenges of traditional parking garage ventilation systems are;

• Air doesn’t reach all areas with the garage, thus resulting in ‘hot spots’ and ‘dead zones’.
• Ducted ventilation systems don’t induce much airflow from a distance
• Supply & extract fans need longer run-time to meet the code requirements recommended by ASHRAE & IMC, which compromises their energy efficiency.
• Ducted ventilation systems waste space

Introducing Jet Fans systems in ventilation design for parking garages

Jat fan system is a cost-effective alternative to traditional ducted ventilation systems in parking garage facilities. It involves putting arrays of jet fans (small ceiling-mounted impulse fans) in strategic locations to direct supply air from the air-supply units towards the extraction points, thus ventilating the entire garage in the process. Moreover, this concept of MEP design for parking garages allows supply air to be delivered in various ways. For instance, you can use supply-air fans, fresh-air openings (grilles), or through vehicle exit/ entrance ramps.

One notable benefit of using jet fans in parking garages is that you can position them between structural elements in the building, Plus, they allow for easier maintenance and lower height requirements since they don’t need any ductwork.

How Jet Fans work

High induction jet fan systems generate a relatively high discharge velocity, causing the discharge air to collide with the air in front of the jet fan to thrust it forward. At the same time, this collision creates friction that draws the surrounding air to create an induction effect that moves it in the airflow direction.

More notability, this induction effect ensures that the quantity of moving air is always considerably larger than the amount of air passing through the jet fan. As a result, the induced air volume is always greater than the airflow rating of the fans.

Types of Jet fan systems for parking garages

There are 2 alternative options for jet fan systems available; the induction thrust fan and the Jet Thrust fan.

• Jet Thrust Fan

As the name suggests, this ventilation system uses Jet Thrust fan technology, together with the main exhaust and supply Fans. For that, it can easily eliminate most of the challenges associated with traditional ducted systems.

The fans are properly installed within the parking facility to control air distribution within the building. More importantly, you can use them to create airflow at both low and high levels within the building, making them more efficient than ducted ventilation systems.

Nonetheless, a jet thrust fan acts the same way as a traditional ducted system. To be precise, it draws air into the fan inlet (louver/ grille) and discharges it at a high level towards the exhaust points (fan/ louver/ duct).

A jet thrust fan system consists of small ceiling-mounted UL-certified devices, with hangers, deflectors, and silencers. The largest fan has an inner dimension of 16”, while the smallest measures 12”. Moreover, it has a UL-rating of 705 temps, so it can withstand 500 deg F for 4 hours, exceeding the NFPA standard of 4282 deg for an hour for tunnel ventilation.

Best of all, a jet thrust fan can offer 10 air changes per air, which is double most traditional ducted systems, thus making it suitable for smoke evacuation purposes. Plus, this system allows the patrons to see the exits and makes it easy for the fire department personnel to get to the fire source since the fans are reversible.

• Induction Thrust Fan

Induction thrust fan systems feature small ceiling-mounted UL-705 devices with a lower height profile compared to the jet thrust fan. However, these ventilation systems are only used for pollutant clearance and ventilation.

Benefits of using jet fans in parking garages

Using high induction jet fans in ventilation design for underground parking provides several key benefits over conventional ventilation systems. Some of these benefits include;

• Energy efficiency

Unlike traditional ducted ventilation systems, induction jet fan systems are controlled by gas detection. As a result, they operate more efficiently, thus reducing their energy consumption.

• Space saving

Jet fans can be attached directly or suspended from the ceiling as they have a small & compact design. For that reason, they’re suitable for car parks with limited space or low ceiling heights.

• Flexible design

The flexibility of the exhaust fan location and jet fan positioning makes this ventilation design a particularly effective option for new construction facilities and renovations.

• Effective ventilation

Induction jet fan systems thrust air throughout the entire parking garage. This eliminates ‘dead zones’, allows effective mixing of air, and reduces the risk of carbon monoxide buildup by ensuring air reaches every corner of the car park.

• Cost savings

Lastly, induction jet fans reduce the costs associated with materials and installation time since they don’t need any ductwork.

Final Words

Although using jet fans in ventilation design for parking facilities is a relatively new concept in the United States, it’s quite common in Europe, where it’s used for life and fire safety. And as you’ve seen it offers other benefits like improved air quality, increased number of parking spaces and reduced construction & running costs.

To learn more about this innovative concept, contact Innodez Design & Engineering today!