Importance of Ventilation Systems for Underground Parking

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Car parking in shopping malls are usually underground and are almost closed in all directions. So, these places in malls require a good ventilation system for removal of exhaust gases produced and to provide fresh air inside the parking space before a person gets suffocated. Most of the shopping complexes in Hyderabad lack a good ventilation system in the parking space. Apart from ducted ventilation, there is one more type of ventilation system consisting of jet fans and exhaust fans which can be used in car parking for removal of exhaust gases. These type of ventilation systems are called as ductless ventilation systems. It is latest system of ventilation and are being used in ventilating road tunnels, metro tunnels etc, where the availability of space is less.

Ductless ventilation system in car parking

Ductless ventilation systems use series of jet fans and exhaust fans for removal of exhaust. Jet fans provide a high velocity to the gas stream entering into it and propagate it to the next jet or exhaust fan. The gas stream received by the exhaust fan is then released into the outside surroundings. Ductless ventilation system has many advantages over the ducted system. Some of the advantages are as follows.

- As ductless ventilation has no channeled parts, it is easy to install when compared to long ducts in ducted system. The overall installation time and cost for ductless system is less.
- The total weight of installation is very less because there are no ducts available, the impeller of jet fan is made of light weight corrosion resistance aluminum which has less density and the outer casing is made of stainless steel instead of cast iron.
- In some situations, installation height of duct restricts the overall height of the basement, which is convenient to park only small and medium cars causing difficulty for bigger vehicles like SUVs. In the case of ductless system, we will not face this issue.
- Ducted system have fresh air fan and exhaust fans, which are operated all day and consumes more power. In case of ductless systems, jet fans are synced with CO2 detector, which operates according to the amount of CO2 in the parking space.

In case of fire accidents inside the parking space, ducted systems will operate in the same conditions as they do not have any CO2 sensor. Having CO2 sensor for ductless system helps to adjust its speed and it removes smoke inside the space with higher rate than ducted system.
Ductless systems that have EN 12101-3 certification and their jet fans can function for 2 hours at 300^oC. This high temperature is obtained only if there is a fire accident in the space and operating for 2 hours facilitates the evacuation of people from the parking space. In case of ducted system, ducts are made of low melting point materials and it easily melts in case of fire accident.
Jet fans used in ductless ventilation system can be operated in single direction or in both directions.
Computational fluid dynamics (CFD) is employed before the installation of each jet fans in the parking region. In case of ducted system no CFD analysis is performed before installation.