Top Safety Considerations of Enclosed Parking Garages
Reading time: 3 minutes
Mechanical engineers responsible for designing underground and enclosed parking garage ventilation systems juggle many challenging demands. From code requirements and safety concerns to space limitations and design aesthetics, there are numerous considerations when designing an effective system.
While there are many factors to consider, all car park ventilation systems are guided by one primary goal: Keeping people safe.
It is easy to lose focus of this primary goal, assuming that building codes and standards provide a safeguard against safety risks. However, there are instances in which these guidelines fall short.
Learn how to effectively address the top safety concerns of enclosed parking garages and improve indoor air quality with these insights in mind.
Safety Considerations of Enclosed Parking Ventilation Systems
A poorly designed car park ventilation system can literally cost the lives of inhabitants. Smoke and gas from a fire can cause lung contamination, dangerous heat levels, and reduced visibility of evacuation routes. In this scenario, it is up to the garage ventilation system to effectively extract the smoke, reduce heat and prevent any injuries or casualties.
But safety risks are not limited to extreme disasters like sudden fire outbreaks. In fact, some of the biggest safety risks of enclosed parking garages are those that occur every day.
Exhaust gases from the cars operating inside the garage include toxic fumes like Carbon monoxide (CO) and Nitrogen oxide (NO). CO is completely odorless, tasteless, colorless, and causes the most non-drug poisoning deaths per year in the U.S.. Without proper ventilation, these fumes can accumulate to dangerous levels throughout the space, endangering the health of inhabitants and increasing the risk of fire.
Safety Guidelines Outlined by Codes and Standards
In an attempt to improve safety, building codes outline specific requirements to ensure ventilation systems effectively remove pollutants from enclosed parking garages.
The International Mechanical Code (IMC) and ASHRAE 62.1 both stipulate that garage ventilation systems run continuously during building-occupied hours to a minimum ventilation rate of 0.75 CFM per square foot of parking deck. However, these standards can vary based on local jurisdiction. For example, the City of Chicago requires 1.0 CFM.
If the ventilation system uses a carbon monoxide sensor-based, demand-controlled ventilation (DCV) system, then the Continuous Ventilation Rate may be reduced to 0.05 cfm per square foot of parking deck with the ability to increase to 0.75 CFM. Similarly, this can vary based on local jurisdiction. The State of California requires the reduced ventilation rate to be no less than 0.15 CFM.
Where the Codes Fall Short
While building codes have moved the industry in the right direction, there are common challenges that are not clearly addressed by these standards. John Gramke, National Sales Manager of Commercial Car Park Ventilation at Systemair, explains:
“Selecting a fan to better circulate and optimize an underground parking garage ventilation system should not be based solely on airflow CFM. More accurately, it should be based on a combination of the fans rated ability to induce airflow, mix and dilute the contaminants while being moved towards evacuation.”
Traditional sweep or ducted systems can meet the minimum CFM rate required by the code but fail to provide fully effective ventilation. The most common pitfall is the inability to move air far distances. When ventilation systems are unable to move air throughout the entire space, exhaust gases can build up in particular areas and create dangerous “dead zones” or “hot spots” of toxic fumes.
How to Minimize Safety Risks
Induction jet fans offer an ideal solution for improving both safety and efficiency in enclosed car parks. These fans produce a high velocity airstream that induces and moves a larger volume of air than traditional ventilation systems, eliminating the risk of dead zones.