Air Conditioning

Central air conditioning systems generally cost $3,000 and upwards to buy and install, while room units start at less than $300 (uninstalled). Typical Alberta operating costs are $100 a year for central systems and $30 a year for each room air conditioner.	Involves meeting with a contractor, at least for a central system, and figuring out your needs if you install a room air conditioner yourself.	A central air conditioner used 300 hours a year emits about 0.7 tonnes of greenhouse gases, though energy-efficient units will produce less.

Should I consider installing air conditioning, or replacing an existing system, in my house?

Given our relatively short, moderate summers, air conditioning is not a necessity for the large majority of Alberta homeowners. If your home is uncomfortably hot in the summer, the best, and most cost-effective, remedy may be to upgrade the insulation in your attic and external walls if it is thin. Other ways to keep out the summer heat include replacing old, leaky windows with energy-efficient models (especially ones that open, helping improve circulation), installing light-blocking curtains or external shades, mounting ceiling fans and planting shade-providing trees and shrubs. You can also keep the furnace fan running, pushing cooler basement air through the house, though this can consume considerable electricity. Only if such measures fail to cool your house sufficiently should you consider air conditioning, which often requires large amounts of energy to operate.

Is a ground-source pump another alternative to air conditioning?

It can be. These so-called geothermal heating systems can be reversed in the summer, pumping warm house air into the ground and thus keeping the house cool. But they are expensive to install (roughly $25,000) and use a fair amount of electricity to operate the pump.

If I still want to purchase a new air conditioner or replace an old one, are there energy-efficient options?

Yes. Since the 1970s, the amount of electricity used by residential air conditioners has dropped by about 15 per cent per decade, thanks to improvements in such things as coil designs, compressors and circulation systems. Indeed, today’s most efficient air conditioners use 30 to 40 per cent less energy than models sold 10 or 15 years ago.

How can I find these efficient new air conditioners?

One way to identify and compare the energy efficiency of different models is to check the EnerGuide rating label on any new air conditioner. On central air conditioners, the energy efficiency is measured by a seasonal energy efficiency ratio (SEER) and an energy efficiency ratio (EER); room air conditioners just have an EER measurement. For both ratios, the higher the number, the more energy efficient the model – the reverse of the EnerGuide rating for most appliances.

High-efficiency room units, for example, generally incorporate efficient rotary compressors, large evaporators and condensers with louvered fins and internally rifled tubes, as well as efficient fans and a slinger ring to deposit water collected from the evaporator onto the hot condenser. Minimum-efficiency units tend to use small conventional heat exchangers and standard compressors and fans.

The most efficient air conditioners are awarded an ENERGY STAR® symbol. To earn that distinction, central air conditioner systems must be about 20 per cent more efficient than standard models, while room air conditioners must be at least 10 per cent more efficient. Hundreds of models now meet these ENERGY STAR criteria, with top-end units now reaching a maximum SEER number of 17 and approaching EER numbers of 13 (by comparison, typical EER numbers in the 1970s were only around 6). ENERGY STAR units don’t cost a lot more than non-qualifying models and will more than pay for themselves, in energy savings, over their lifespan – 15 or more years for a central system and about 10 years for a room air conditioner.

What kind of air-conditioning system do I need?

There are two primary types – central and room air conditioners. Central air conditioners are designed to cool, and dehumidify, the entire house, typically with a large outdoor compressor and coil connected by refrigerant lines to an indoor coil mounted in the furnace; the air conditioner uses the furnace’s duct system to distribute cool air. Central air conditioner systems are more efficient than room air conditioners, but if only one or two rooms need cooling, it probably makes sense to use room air conditioners, normally mounted in an open window and plugged in.

How much do they cost to buy and operate?

Expect to pay upwards of $3,000 to buy and install a central air conditioning system – the price can go up considerably if much ductwork is required. By contrast, room air conditioners start at less than $300, though the installation price will be somewhat higher if it’s a through-the-wall unit, instead of a simple window-mounted model.

Depending on how much you use it, air conditioning can account for up to 50 per cent of your summer electricity bill. A room air conditioner typically consumes one kilowatt of electricity per hour, while a central system uses about 3.5 kWh. According to Enmax Utilities, a typical central air conditioner in Alberta operates for about 300 hours per year, thus consuming some 1,050 kWh of electricity, at an annual cost of more than $100 (at 10 cents per kWh).

What do I need to know about sizing and installation?

It’s important to choose an air conditioner with the proper cooling capacity for your needs. For example, an oversized unit will be more expensive to buy and may not stay on long enough to properly dehumidify the space, while an undersized one may be unable to handle the cooling load in extremely hot weather. Ideally, the unit should be sized by a qualified air conditioning contractor, using detailed calculations that take into account factors such as the size of rooms, insulation levels, size and orientation of windows and doors, shading, number of occupants, appliances, lighting and climate. The contractor should also be able to tell you if additional wiring, ductwork or other modifications are required. While a simple window-mounted room air conditioner can be installed by the user, central systems generally require an experienced, professional installer.

Where can I find a qualified air conditioning contractor?

The Heating, Refrigeration and Air Conditioning Institute of Canada (HRAI) maintains a list of qualified, licensed member contractors. Click here to find a contractor in your area.

What operating tips should I follow to maximize the energy efficiency of an air conditioning system?

• Keep your air conditioning thermostat set at 25 degrees Celsius or higher, and you’ll save up to five per cent on electricity use for every higher degree. If you’re away for more than four hours, set the thermostat to 28 C. (a programmable thermostat can automatically make these adjustments).
• The simultaneous use of ceiling fans (make sure they’re blowing downward in the summer) allows you to set the A/C thermostat higher and still feel comfortable. Ceiling fans use considerably less electricity – about a penny an hour – than air conditioners.
• Turn the air conditioning off at night and keep the windows open. You can also use the fan-only mode, on some units, to draw cooler evening air into the house.
• Try to place room air conditioners in a shaded window – exposing them to direct sunlight can increase their energy consumption by five per cent.
• Don’t let the heat build up all day and then turn on the A/C at its maximum setting. It’s much more energy efficient to start the unit earlier in the day and let it gradually cool and dehumidify the space.

What maintenance is required?

Follow the manufacturer’s recommendations for regular cleaning and maintenance. For optimal performance, clean or change air filters regularly and ensure the airflow through indoor and outdoor vents is not blocked.

How do I properly dispose of an old air conditioner?

Never send an old air conditioner to a landfill. Many older units contain environmental contaminants such as chlorofluorocarbons (CFCs) in refrigerants as well as mercury and hydrochlorofluorocarbons (HCFC). Consult your Yellow Pages™ or your municipality about appliance collection and recycling programs, especially for room air conditioners; qualified technicians are needed to recover and reclaim older refrigerants. Note: All new air conditioners must use refrigerants that meet increasingly strict environmental standards.