Dilution Ventilation Strategy

When it comes to enclosed and underground parking garage ventilation, the effectiveness
of the system can profoundly impact the health and safety of occupants. With severe
contamination from exhaust gases, CO and NO2, mechanical engineers are tasked with the
daunting challenge of keeping the space healthy with proper ventilation.
But safety isn’t the only consideration mechanical engineers must weigh when designing
their ventilation systems. From energy efficiency to code requirements, each application has
unique design needs and challenges.
Challenges of Traditional Car Park Ventilation
In North America, code requirements according to the International Mechanical Code (IMC)
and ASHRAE stipulate that garage ventilation systems run continuously while occupants are
present to ensure a safe environment. These codes outline specific ventilation rates and
sometimes varying based on local jurisdiction. Sweep ventilation systems are part of an
effective design strategy but oftentimes additional solutions are required to optimize
performance.
“It’s easy to move the correct volume of air specified by the codes,” explains John Gramke,
National Sales Manager of Commercial Car Park Ventilation at Systemair. “The challenge is
how to mix, dilute and evacuate the contaminated air in an effective and efficient manner.”
There are a number of additional challenges posed by traditional car park ventilation
systems:
1) Traditional ventilation systems do not induce much airflow from a distance
2) Air cannot reach all areas within the car park, resulting in “dead zones” and “hot spots”
3) Supply and exhaust fans require longer run-time to be code compliant, compromising
energy efficiency
4) The effective life of gas monitoring systems is often reduced
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Makeshift Solutions Compromise Performance