Carbon monoxide control is a major challenge in covered car parks. In absence of proper ventilation system, parking facility presents several Internal Air Quality problems. Most serious is the emission of high levels of Carbon-Monoxide (CO) as it is easily absorbed by Hemoglobin in Human Blood inhibiting Oxygen delivery to body causing adverse health effects varying from headache to death. Thus ventilation system should have adequate air movement inside the basement when operating under normal conditions; should be able to satisfactorily dilute/extract CO produced from vehicles.
By using CFD analysis we ensure that the ventilation system meets the NBC, ASHRAE and WHO guidelines for CO exposure and contaminant control etc. The working of staircase pressurization, zone modelling for CO removal can also be analysed. For a large car park the zoning can also be done to utilize lesser fans to control the CO. This optimizes the system for energy saving in the long run.
The main objectives of any such typical study are listed below:
-Investigate the performance of the system, so that there is adequate air movement throughout the car park under normal operating conditions.
-The event of a CO high level (>100 PPM) is avoided at short term exposure of 30 min [3].
The acceptance contaminant level criterion for parking garages is recommended in ASHRAE 2007 Handbook. According to ASHRAE, the main criterion for car park is the carbon monoxide level, which is to remain below a designated peak value. ‘Parking garages ventilation rate designed to maintain a CO level of 40 mg/m3 (35 ppm) for 1 Hour exposure, with a maximum of 130 mg/m3 (120 ppm) for 15 minute exposure’.
The output of analysis in in the form of report containing velocity profiles, temperature and CO profiles at different planes. In addition the compliance summary with the standards is also provided.
Some images are given below showing the results of CO simulation in Car park.