Guide to Choosing an Energy Efficient Air Conditioner

When summer rolls around, your air conditioner is your home’s MVP. Everyone appreciates shelter from Alberta’s summer heat and humidity, but that relief shouldn’t come at an unaffordable price. One of the most effective ways of controlling cooling costs is to use an energy-efficient air conditioner. If you have a watchful eye on Alberta electricity rates as the heat and humidity rise, it might be time to consider an efficiency upgrade to your cooling system. 

Let Direct Energy walk you through the most important steps to evaluating your cooling needs and choosing the best energy-efficient air conditioner for your home.

Different Types of Air Conditioners

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Central air conditioning, mini-split systems, and window units all make use of the same cooling technology, but they're designed for different living situations. Depending on your home and budget, one type of air conditioning may be a much better fit than the others.

Central Air Conditioner

A central air conditioner is designed to cool multiple rooms, and usually an entire home, at one time. Homeowners control these systems with a wall-mounted thermostat, and the air conditioner circulates cool air through a system of ducts and vents until the indoor air reaches the temperature set on the thermostat.

Central air conditioners consist of three main components: a condenser, a compressor, and an evaporator. Liquid refrigerant circulates through copper tubing between the outdoor condenser and the indoor evaporator, where it absorbs heat from inside the home. The heat vaporizes the refrigerant and sends it to the compressor, where it is pressurized to allow the heat to be expelled outdoors. From there, the refrigerant is depressurized and converted back into a liquid, where it cools on the way back to the evaporator. A fan blows air over the cold evaporator coils and into the duct network, sending cool air all over the home.

Pros of central air conditioning:

  • Whole-home comfort: A professionally installed unit should keep the entire space a consistent temperature.
  • Quiet operation: Because the noisiest parts of the system are typically located outdoors and in attics, basements or utility rooms, central air systems are generally quieter than window units and mini-split systems.
  • Cleaner air: Central air conditioners are constantly filtering and replacing the indoor air, removing irritants, allergens, dust, and even pet hair.

Cons of central air conditioning:

  • Requires ductwork: The cost of installing ductwork is often greater than the cost of installing a central air system, which can make central air a pricey solution for modernizing older homes.
  • Purchase cost: Compared to window units and small-scale mini-split installations, central air conditioning is generally the most expensive option in terms of purchase and installation.
  • Wasted energy: Because central air systems are designed to cool an entire home to the same temperature, you can’t save money by focusing on cooling on occupied rooms and leaving unoccupied rooms warmer.

Mini-Split Systems

Mini-split systems absorb heat and produce cool air using the same basic technology as central air, but their design is significantly different. With this system, each cooled room has its own evaporator and fan unit, usually installed high on the wall. These units then share a single outdoor condenser and compressor unit.

Pros of mini-split systems:

  • Zone control: Each evaporator and fan has its own thermostat, allowing you to save money by adjusting the temperature higher in unoccupied rooms.
  • No ductwork needed: Because there’s no ductwork, mini-split systems may be a more affordable solution for home additions or for retrofitting older homes with a central air experience.
  • Unobtrusive design: The wall-mounted units may be more aesthetically pleasing than window units and won’t take up the whole window.

Cons of mini-split systems:

  • Energy efficiency: In general, mini-split systems are less efficient than central air systems. However, because there’s no cooling loss through ductwork and users have zone control ability, homeowners may be able to make up this difference by being disciplined with the thermostats.
  • Installation costs: The costs increase with each evaporator unit, so depending on how many rooms you want to cool, installation may also be more expensive than with central air.
  • Design tastes vary: While sleeker than window units, mini-split systems don’t offer the nearly invisible cooling of central air. For homeowners who don’t want any visible cooling equipment at all, central air is a better fit.

Window Units

Window units are air conditioners you can buy at many hardware and department stores.

Pros of window units:

  • Low cost: Window units are significantly less expensive to buy than central air or mini-split systems, and they don’t require professional installation.
  • Affordable efficiency: High-efficiency window units generally don’t cost substantially more, yet they can really help you save over time.
  • Flexibility: Window units can be placed anywhere with an exterior window and an electrical outlet within reach.

Cons of window units:

  • Aesthetics: Window units obstruct your view of the outdoors and drip condensation down below, which not all homeowners love.
  • Noise: Because all of the components are so close to your living space, expect window units to be louder than the alternatives.
  • Warm air infiltration: Improper installation can result in a poor seal around the window unit, which will let warm air and potentially even pests inside.
  • Security concerns: A window with an air conditioner is less secure than one that is closed and locked.

Air Conditioner Efficiency – Choosing the Right Size

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When shopping for a new air conditioner of any type, size matters. And that doesn’t just mean physical size “size” is also shorthand for the unit’s cooling power, typically expressed in British thermal units or BTUs.

Size is important for two reasons. If an air conditioner is too small, it will run constantly without ever fully cooling the space. That will leave you with both a high energy bill and an uncomfortable house. If it is too large, it will cool the house too quickly. That might sound nice, but air conditioners dehumidify the air at the same time they cool it, and you can’t speed up the dehumidification process. So, when an oversized air conditioner cools a home too quickly, it leaves excess moisture behind, leaving the air feeling damp and clammy.

When buying a central air conditioner or mini-split system, you should have your home measured and inspected by a professional who can recommend the proper size. These systems are high-involvement purchases that require professional installation and typically cost a few thousand dollars, so you definitely want an accurate size calculation, not a ballpark estimate.

But since you wouldn’t hire a professional to install a window unit, you'll have to calculate the size of these units yourself. Measure the dimensions of the area you want to cool and use this ENERGY STAR chart to see how many BTUs you need. Take note of the tips to adjust the BTU count if the room you're cooling is shady, sunny or a kitchen.

How to Choose the Right Energy Efficient Air Conditioner

It pays to choose an energy-efficient air conditioner, so how do you make sure you get a good one? The answer is to pay close attention to the product labels.

Window Units

All new window units come with an EnerGuide label which tells you how much energy the model uses. If it’s an especially efficient model, it will also come with an ENERGY STAR symbol attached.            

  • EnerGuide Label

The EnerGuide label helps consumers compare models. You’ll likely see information about how much energy the model uses in kilowatt-hours and how it compares with other more efficient and less efficient models.

  • ENERGY STAR Symbol

On average, an ENERGY STAR certified window unit uses 10 percent less energy than a standard model. Lower energy consumption means a lower energy bill and savings in your wallet.

Window units earn the ENERGY STAR symbol based on their Combined Energy Efficiency Ratio, or CEER. The higher the CEER, the more energy-efficient the unit. The minimum CEER to qualify for ENERGY STAR certification varies based on the size of the unit, but it ranges from about 12 for smaller units to about 10 for larger units. You can browse certified units on the ENERGY STAR website.

Central Air Conditioners

Central air conditioners use the Seasonal Energy Efficiency Ratio (SEER), which is similar to CEER. The higher the SEER, the greater the efficiency. Central air conditioners with a SEER of 15 or greater qualify for ENERGY STAR certification and use eight percent less energy on average than systems that do not qualify.

The easiest way for most homeowners to identify and compare ENERGY STAR certified central air conditioners is to work with a reputable professional installer. But if you want to browse equipment online to see detailed efficiency data and identify ENERGY STAR certified units, use the Consortium for Energy Efficiency (CEE) online database.

Best Features of an Energy Efficient Air Conditioner

There are several energy-saving features to look for when shopping for a new energy-efficient air conditioner.

Programmable Temperature

Most modern window units have a digital temperature display that allows you to set your temperature. The unit will automatically shut off when it reaches that temperature. Generally, the recommended temperature is between 25° and 27° C.  You’ll likely appreciate the energy savings too, as the unit won’t run when it isn’t necessary.

Energy-Saving Mode

Some window units also have an energy-saving or economy mode that will turn off the fan when the area is sufficiently cooled down. This may provide less breeze and air circulation, but if the unit allows you to program your desired temperature, the fan will turn back on automatically when cooling mode resumes.

Wifi-Enabled Smart AC

The most sophisticated air conditioners can connect directly to your home wifi network, allowing you to control the system from anywhere with a smartphone or tablet. If this feature isn’t built into your system, you can get the same functionality with a smart thermostat. Smart systems make it easy to customize cooling schedules, and some can even learn your preferences over time to intuitively save you money. An ENERGY STAR certified connected or “smart” thermostat can save at least 8 percent of energy used in heating and cooling your home.


Air conditioner technology is constantly improving to make modern units more energy-efficient and user-friendly. Planning an upgrade in your cooling equipment is a smart way to save money, but you can save even more by shopping around for the best energy deal. Be sure to compare different energy companies in Alberta, and, explore Direct Energy’s electricity and natural gas rates.

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