Choosing the Right Power for Your Wall-Mounted Air Conditioner: A Crucial Step for Your Comfort
At AirGreen, we know that selecting the power of a wall-mounted air conditioner is not a simple task. It’s a key factor in ensuring optimal comfort while also avoiding energy waste. An underpowered unit will struggle to cool your space, while an oversized air conditioner will lead to excessive consumption and inefficient cycling. That’s why we provide a complete guide — illustrated with real installation cases from Montréal, Laval, Longueuil, Rive Nord, and Rive Sud — to help you understand how we calculate the perfect power for each client.
Why Is the Power of a Wall-Mounted Air Conditioner So Important?
Balancing Energy Efficiency and Comfort
A properly sized wall-mounted air conditioner ensures:
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A stable and pleasant indoor temperature
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A longer lifespan for the unit
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Controlled energy consumption
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Optimal eligibility for subsidies like Hydro-Québec's LogisVert program
The Technical Criteria Used by AirGreen to Size a Wall-Mounted Air Conditioner
We use a rigorous method based on several key parameters:
Room Size
This is the starting point. In general:
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For a 15 to 25 m² room, we recommend a 9,000 BTU unit.
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For 25 to 35 m², a 12,000 BTU model.
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For 35 to 50 m², we opt for an 18,000 BTU unit.
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For larger spaces of 50 m² or more, a 24,000 BTU unit or higher is usually required.
Room Orientation
A room facing south receives more sunlight, so:
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We increase the estimated power by about 10 to 15%.
Ceiling Height
Rooms with high ceilings require more power to achieve the same thermal comfort, so we adjust the calculation based on the room's volume.
Insulation and Window Type
A well-insulated home with energy-efficient windows will need less power than a building with poor insulation.
Appliances and Heat Sources
The presence of appliances, strong lighting, or even computers in a room contributes to the heat load.
Real Examples of AirGreen Installations with Power Calculations
Montréal (Rosemont) – 60 m² Apartment Facing South
Problem: The client had an old, inefficient portable air conditioner. High summer temperatures and excessive consumption.
AirGreen Solution: After inspection:
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Room size: 60 m²
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Orientation: South
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Good insulation
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Regular kitchen appliance use
👉 Model Chosen: Gree Lomo 24,000 BTU
👉 Result: Quick cooling, stable cycles, client eligible for a $1,860 LogisVert subsidy.
Laval (Chomedey) – 40 m² Condo, Average Insulation
Problem: The old 12,000 BTU mini-split couldn’t keep up during heatwaves.
AirGreen Assessment:
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Room size: 40 m²
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Orientation: North-West
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Average insulation, large single-pane window
👉 Proposed Installation: Fujitsu KZAH 18,000 BTU
👉 Benefit: Better temperature control, reduced short cycles.
Longueuil (Vieux-Longueuil) – Open Living Room and Kitchen, 35 m²
Context: New family wanting a quiet, energy-efficient wall-mounted air conditioner.
Analysis:
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Room size: 35 m²
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Orientation: West
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Good insulation
👉 Recommendation: Sharp ZU1 15,000 BTU, inverter technology
👉 Result: Efficient performance, quiet operation, eligible for $2,172 in subsidies.
Practical Tips to Avoid Common Mistakes
Don’t Rely Only on Room Size
A common mistake is to base the decision solely on square footage. Always consider all thermal factors.
Avoid Overpowered Air Conditioners
Oversized units lead to frequent on/off cycles, which:
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Reduces the unit's lifespan
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Increases consumption
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Affects comfort by causing temperature fluctuations
Hire a Certified Professional
At AirGreen, our technicians conduct a free on-site evaluation, consider all your home’s specifics, and recommend the most suitable unit, maximizing potential subsidies.
Why Choose AirGreen for Sizing and Installing Your Wall-Mounted Air Conditioner?
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Recognized expertise in installing heat pumps and wall-mounted air conditioners across Montréal, Laval, Longueuil, Rive Nord, and Rive Sud
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Access to top brands on the market: Gree, Fujitsu, Sharp, Senville, etc.
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In-depth knowledge of government subsidy programs
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Transparent, personalized customer service
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Compliance with safety and aesthetic standards (duct installation, discreet housing, optimal positioning)
A Few Differentiators in Our Installations
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Comprehensive thermal analysis offered before installation
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Strategic positioning of the indoor unit for optimal air distribution
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Discreet outdoor wall installation, compliant with municipal regulations
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Post-installation follow-up and personalized maintenance advice
In Conclusion
Calculating the right power for a wall-mounted air conditioner is not just about numbers — it’s a technical skill that requires experience, precision, and an understanding of each client’s specific needs. At AirGreen, we combine technology, expertise, and personalized service to guarantee sustainable and energy-efficient comfort.