Investing in a high-performance commercial air conditioning system is a strategic decision for any building manager, business owner, or operations administrator. Yet, a far too common mistake — oversizing the air conditioner — can turn a logical investment into an energy and financial sinkhole. At AirGreen, we’ve observed across our many installations in Montreal, Laval, Longueuil, the North Shore and the South Shore, that this so-called “smart” idea leads to major consequences in comfort, equipment longevity, and operating costs.
The “bigger is better” myth in commercial air conditioning
The common assumption is that a more powerful unit will deliver better comfort. But in the world of commercial HVAC, the reality couldn’t be more different. An oversized air conditioner doesn’t improve performance — it undermines it.
Why an oversized system is a problem
-
Short and frequent cycles: An overpowered unit cools the air too quickly, without having time to properly dehumidify the space. This results in discomfort, despite what the thermostat says.
-
Premature wear of components: Frequent and short start-ups place excessive strain on the compressor, drastically reducing the system’s lifespan.
-
Excessive energy consumption: A system that’s constantly turning on and off uses significantly more energy than a properly sized unit running at a steady rate.
-
Temperature fluctuations: Instead of maintaining a stable temperature, the system creates cold bursts followed by warm spells. A nightmare for both clients and employees.
-
Needlessly high installation cost: A more powerful unit costs more to purchase and install and may require upgrades to your electrical system or ductwork.
Real case study: a business in Longueuil
We were recently called by the owner of a restaurant in Longueuil, who had a 10-ton air conditioner installed for a 2,000 square foot space. During the first summer season, he noticed high electricity bills, constant humidity in the dining area, and customer complaints. After our evaluation, we recommended replacing it with a 6-ton unit better suited to the space, with smart temperature control. The result: a 31% reduction in annual energy bills and finally stabilized indoor comfort.
How to determine the right size for your commercial air conditioner
Thermal load assessment: the foundation of any successful installation
At AirGreen, we always conduct a full thermal load analysis of your building before recommending any equipment. This evaluation takes into account:
-
The square footage to be cooled
-
The orientation of the building
-
The number of occupants
-
The type of commercial activity
-
Internal heat sources (kitchen equipment, servers, lighting)
-
The thermal insulation and building materials
-
Outdoor air inlets and mechanical ventilation
This tailored approach helps optimize your investment, ensure optimal comfort, and guarantee high energy efficiency.
The key role of power modulation
Proper sizing alone isn’t enough. We prioritize commercial models with Inverter technology, which can adjust their output in real time according to thermal load. These systems significantly reduce temperature swings and extend the lifespan of your equipment.
Practical tips to avoid oversizing
-
Don’t rely on rough rules of thumb: “1 ton per 400 square feet” is an oversimplified estimate. Every building is unique.
-
Work with a commercial HVAC professional: Don’t base decisions on general advice from manufacturers or big box store sales reps.
-
Always request a full thermal assessment: It’s the only way to avoid sizing mistakes.
-
Ask for technical documentation with your quote: It should include the estimated required output and a breakdown of the thermal calculation.
-
Prioritize high-efficiency ENERGY STAR certified systems, which are also eligible for local subsidies.
Available subsidies: an incentive to size it right
In Quebec, several programs encourage businesses to choose efficient and properly sized systems. For example:
-
Hydro-Québec’s LogisVert program for small commercial properties
-
Transition Énergétique Québec (TEQ) for energy-efficient renovations
-
Municipal grants available in Laval, Longueuil, Montreal, and the South Shore
An oversized system may be ineligible for these subsidies, as it doesn’t meet energy efficiency criteria. This is yet another reason to trust your commercial HVAC installation to experts like AirGreen.
The AirGreen advantage: precision, reliability, efficiency
We’ve managed dozens of commercial air conditioning projects in Montreal, Laval, the North Shore, and the South Shore. Our commitment: to design systems that are perfectly sized, installed to the highest standard, and with meticulous attention to long-term performance.
Some of our recent projects:
-
Administrative office in Laval: 27% energy savings after proper system downsizing.
-
Dental clinic in Brossard: eliminated excessive humidity caused by an oversized system.
-
Hair salon in Montreal: regulated thermal comfort after replacing a 5-ton unit with a 3-ton Inverter model.
Key takeaway
An oversized commercial air conditioner, far from being a luxury, can become a technical and financial burden. To ensure a comfortable indoor climate, controlled energy use, and maximum lifespan for your system, proper sizing is essential. At AirGreen, we bring our expertise in commercial HVAC to every project, with precision, transparency, and long-term performance in mind.