Why These Misconceptions Harm Your Comfort, Your Health, and the Efficiency of Your HVAC System in Greater Montréal
During our many service calls with clients in Montréal, Laval, Longueuil, the North Shore, and the South Shore, we consistently notice the same issue: residential ventilation is still widely misunderstood. Many people make major decisions about their ventilation system based on old misconceptions, often passed down by neighbors, forums, or outdated practices. At AirGreen, we want to set the record straight using our on-site expertise and the hundreds of air exchanger installations we’ve completed in recent years.
Here are the 7 most dangerous myths about residential ventilation, and why you need to forget them immediately.
Myth 1: “Opening windows is enough to ventilate a house properly”
This is one of the most widespread myths, and also one of the most dangerous. Opening a window does not ensure effective air renewal, nor does it control humidity. Outdoor air can be polluted (pollen, fine particles, urban CO2) and doesn’t circulate evenly throughout different rooms.
A mechanical ventilation system (such as an HRV or ERV air exchanger) does the job by:
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Providing continuous air renewal, 24/7.
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Recovering heat or humidity to minimize energy loss.
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Filtering out contaminants, improving indoor air quality.
Myth 2: “You don’t need an air exchanger if you have a heat pump”
False. A heat pump or wall-mounted air conditioner provides heating and cooling, but does not renew indoor air. Air exchangers are essential to:
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Remove humidity from bathrooms, kitchens, and basements.
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Prevent mold growth.
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Maintain healthy indoor air by eliminating pollutants.
Myth 3: “An air exchanger wastes energy”
This myth is based on a misunderstanding of how modern HRV (heat recovery ventilators) and ERV (energy recovery ventilators) work. These units:
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Recover up to 80% of the heat from the outgoing air.
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Reduce the need for heating in winter and cooling in summer.
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Are eligible for LogisVert subsidies if ENERGY STAR certified and achieving a Sensible Recovery Efficiency (SRE) of 65% or more.
Myth 4: “Outdoor air is more polluted than indoor air”
In many cases, it’s the opposite. Indoor pollutants (VOCs, mold spores, fine particles, formaldehyde, CO2, dust mites) can reach concentrations 3 to 5 times higher than outdoor levels. Without ventilation, these pollutants accumulate, especially:
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In building materials.
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Household cleaning products.
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Stagnant moisture in basements and bathrooms.
Myth 5: “All air exchangers are the same”
That’s like saying all cars are the same. Low-end models don’t filter well, are noisy, wear out quickly, and often fall short of performance standards required for government programs.
At AirGreen, we only install models that are:
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HVI and ENERGY STAR certified.
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Equipped with quiet ECM motors.
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Featuring enthalpic or sensible heat recovery based on specific needs.
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Compatible with high-efficiency filters (up to MERV 13).
Myth 6: “Air exchangers don’t need maintenance”
Big mistake. Without regular maintenance:
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Filters become clogged, restricting airflow.
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Energy performance drops significantly.
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Mold and mildew can form in the core or ductwork.
Our HVAC maintenance service includes:
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Complete core cleaning.
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Filter replacement or washing.
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Airflow and pressure checks.
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Duct inspection to prevent contamination.
Myth 7: “New homes don’t need mechanical ventilation”
Not only is that false—it’s against regulations in many cases. Since the Québec Construction Code came into effect, every new home must be equipped with a compliant mechanical ventilation system. Modern homes are so well insulated that they no longer breathe naturally like older buildings.
A properly sized air exchanger helps:
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Meet RBQ and Novoclimat standards.
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Maintain air quality despite tighter building envelopes.
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Access available energy efficiency subsidies.
Real Examples: Recent Installations by AirGreen
Project in Laval
Installation of a Venmar AVS® E15 ECM in a fully renovated bungalow. The client had allergies and was looking for a quiet, high-performing system. After installation:
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Humidity maintained at a constant 45%.
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Improved air quality measured by VOC sensor.
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Nearly silent operation.
Project in Longueuil
Replacement of an old noisy PSC motor air exchanger with a Venmar EVO5 700 HRV featuring an ECM motor:
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Balanced ventilation in all rooms.
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Eligible for a $1,200 LogisVert subsidy.
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Full integration with existing HVAC system.
The Mistakes We Often Correct During Service Calls
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Unit installed too close to a bedroom = nighttime noise.
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Poor duct orientation = polluted air returns to living spaces.
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No slope in the condensation drain line.
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No airflow test performed after installation.
These issues reduce system efficiency and increase health risks for occupants.
Conclusion: It's Time to Let Go of These Misconceptions
These residential ventilation myths may seem harmless, but they can cause serious long-term problems: discomfort, mold, high energy bills, poor air quality. Choosing a high-performance ventilation system, properly installed and maintained, is an investment in:
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Your family’s well-being.
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The durability of your property.
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And substantial energy savings.
At AirGreen, we support you from the initial evaluation to the installation, including grant applications. Contact us for a free quote.