Natural and forced ventilation in an underground car park

The video shows the analysis of a two-storey underground parking lot conducted using the CFD Vento software. The IFC model, shared by Nikolin Risilia from HYDRO&ENERGY, represents three buildings on top of the parking area, which is spread over two underground levels. The simulation included natural ventilation, ensured by two access ramps that connect the first underground level to the ground level, in addition to a light well and several staircases that go from the second underground level up to the ground level. This system is supported by mechanical ventilation, with the use of various Jet Fans and air extractors distributed in the underground floors.

To analyze the effectiveness of a ventilation system in a parking lot, it is crucial to perform accurate design calculations and fluid dynamic checks to ensure that the system is suitable for the size and configuration of the project area. The analysis of a specific case study can provide concrete data on the operability of the proposed system.

Using Vento's Air Exchange feature, it is possible to monitor the evolution of air exchange, identifying areas of ideal exchange and those that require design interventions.

After the first 10 seconds of the video we have shrunk 20 real time minutes in 35 seconds which correspond to the evolution over time of the air exchange. After 35 seconds, a steady state of exchange is reached that remains constant over time.

The three different colors of the clouds indicate three ranges of concentrations between new air and initial old air, expressed in grams per cubic meter. The remaining volume of analysis has a concentration lower than 50 g/m3.

The area colored in blue indicates the minimal presence of old air, primarily located in an area of the -1 floor. However, the majority of this level is occupied by new air, with a percentage of nearly 100% new air.

By removing the blue cloud from the display, the yellow cloud can be seen more clearly extending in small parts of level -1, and covering about half of level -2. The highest concentrated old air (red cloud) is primarily located in the most remote part of the second basement, far from external accesses and devoid of mechanical extraction systems. Despite the air circulation achieved through Jet Fans, in these areas the stale air is unable to exit towards the outside for proper air exchange.