In a commercial building, a failing ventilation system can quickly become a source of unexpected expenses. Poor air quality, system breakdowns, rising energy consumption or even fire hazards are real and costly consequences. Here are the most common mistakes we see, and more importantly, how to avoid them.
1. Underestimating Ventilation Maintenance Frequency
This is the most common mistake: assuming that ventilation systems can “run on their own” for years. In reality, dust, debris, humidity, and airborne contaminants gradually build up inside the ducts. As a result, air moves less efficiently, the system works harder, and complaints from occupants start piling up (along with sneezing).
A minimum annual inspection should be scheduled, with the frequency adjusted based on how the space is used (schools, daycares, healthcare facilities, restaurants, etc.). A preventive maintenance program will save money in the long run.
2. Forgetting the filters (or changing them too late)
Most commercial ventilation systems are made up of ducts, motors, air intake and outlet grilles and filters, typically located at the air intake or near air handling units. These filters are designed to trap airborne particles (dust, pollen, fibers, etc.) before they circulate throughout the building.
When filters are neglected or forgotten, they become saturated. Air can’t flow freely, motors are forced to work harder to maintain airflow, and overall system performance declines.
Common consequences:
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Unusual noises, whistling or vibration
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Reduced airflow or uneven air distribution
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Increased dust and lingering odours in occupied areas
The solution is to establish a clear schedule for filter replacement or cleaning, based on manufacturer specifications and actual usage conditions. A filter that's too clean never causes problems. The opposite? It does.
3. Neglecting post-disaster cleaning
After water damage or a fire, ventilation ducts can become channels of contamination. Moisture can encourage mold growth, while soot and fire-related particles—highly toxic and sometimes carcinogenic—risk being redistributed throughout the building.
Failing to act quickly increases health risks for occupants and can also cause long-term damage to the system. Following any major incident, a complete inspection and thorough duct cleaning are essential to restore safe and healthy air quality.
4. Neglecting kitchen hoods and exhaust systems
In restaurant or cafeteria kitchens, cooking vapours contain suspended grease particles. These particles are captured by the hood located above cooking equipment, then transported through exhaust ducts.
Over time, grease builds up on the inner surfaces of hoods, filters and ducts, forming a sticky layer that can be highly flammable.
This buildup reduces system performance, causes unpleasant odours, and most importantly, increases the risk of fire if open flames or excessive heat come into contact with the deposits.
Regular cleaning performed by certified professionals, with proper documentation, is strongly recommended. Additionally, insurers are increasingly requiring it.
In practice, minimum cleaning frequency varies based on usage intensity, but a quarterly inspection is recommended for most facilities.
📌 Related reading: When Should You Service Your Business Ventilation System?
5. Not documenting interventions
Without a maintenance log, it’s impossible to know what was done, when, or by whom. This becomes a problem when it's time to:
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Pass an audit
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Handle an insurance claim
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Transfer building management to a new person
The simplest approach is to keep a clear, up-to-date log that’s shared with your maintenance provider. It also serves as a useful communication tool to justify certain interventions.
To learn more about our ventilation services, visit our ventilation system maintenance and cleaning page.
