Home > Energy Efficiency Tips & Tools > Heating and Cooling

Heating and Cooling

Cooling Strategies

When the heat hits, keep your cool!

In Ontario, we're subjected to extremes of climate, in both winter and summer. Many of us have taken steps to ensure that our homes are heated as efficiently as possible in the winter. It makes sense to reach the same level of efficiency for summer cooling. Here are some useful cooling ideas and tips on buying air conditioners. A more complete shopping checklist for buying both heating and cooling equipment is here.

Why is there so much heat? Before looking for cooling solutions, consider where the heat actually comes from. In the summer, there are three main sources of heat in a house:
The sun shining through the windows Heat that builds up in the attic Heat from appliances and lights

Your home may get heat from one or more of these sources. Take time to analyze it to find out what your best cooling solutions will be.

In addition to air conditioning and ventilation, you should also consider these low-cost passive cooling ideas to keep your home comfortable.

Choosing the right room air conditioner

If you've decided on a window air conditioner, it's worth doing some planning in advance. Measure the area you wish to air condition. Draw the room floorplan with measurements and window location. Make a sketch of the actual window you plan to use for the air conditioner so the dealer can help you choose a model that fits. Calculating the proper size air conditioning unit is important. An undersized unit will stay on most of the time and not cool sufficiently. A unit rated higher than you need will lower the temperature quickly, but will not stay on long enough to remove the humidity which will leave you feeling cold and clammy. And an oversized unit will usually cost more to buy. Air conditioners are rated in British Thermal Units per hour (Btu/h). Generally, it will take about 18 Btu/h to cool and dry 0.09 m2 (1 ft.2) of floor space.

Here are some rough guides you can follow:

• A 9,000 Btu/h unit will cool up to 45 m2 (500 ft.2)
  
• A 12,000 Btu/h unit will cool about 59 m2 (650 ft.2)
  
• An 18,000 Btu/h unit will cool about 90 m2 (1,000 ft.2)

The benefits of room air conditioners:

• Ideal for cooling one room of a house
  
• Easy to control and adjust
  

Maintenance:

• The filter behind the grill should be washed monthly. Unplug the unit. Remove the filter and wash it, allowing it to dry completely before reinstalling.
  
• In the spring and fall, clean all dirt from the coils. In the fall, unplug the unit, remove it from the window and store in a dry area after cleaning. Replace the storm window.

back to top

What to look for in central air conditioning
A central air conditioner is added to an existing forced air system and uses the ductwork to provide air at a comfortable temperature and humidity. Cooling is controlled by a central thermostat.

Although the initial cost of central air may be relatively high, it is more efficient than operating a number of window air conditioners at once.

Since central air is a major purchase, it is advisable to get a number of quotes from reputable dealers. The dealers can assist you in choosing a unit that is the right size for your home.

It's also a good idea to compare the sound ratings of different units, since some are noticeably quieter than others.

Also, look at the SEER (Seasonal Energy Efficiency Ratio) ratings, since some are considerably more efficient than others. Typical SEER ratings range from 10 to 14, with the higher number representing the more efficient model.

The benefits of central air conditioning:

• Increased comfort throughout the home
• More efficient and quieter than a number of room air conditioners
  

Maintenance:

• Check filters monthly and replace or clean if necessary
  
• Have a professional inspect your unit annually
  
• Keep the outdoor unit free of leaves and grass and cover in winter
  

If you are thinking of adding central air conditioning and replacing a furnace, you should consider a heat pump since it provides both heating and cooling.

back to top

Power ventilation can be an effective alternative
As an alternative or an addition to air conditioning, think about power ventilation systems. There are two types of central units: exhaust-only systems and packaged ventilators.

In homes with an adequate air supply, exhaust-only systems and packaged ventilators are effective for reducing heat and humidity in the summer and providing ventilation year-round. However, in the winter, these systems will exhaust the warm air which will increase your heating costs.

A power ventilator in the attic is one of the most economical methods of reducing indoor summer temperatures. The initial cost is relatively low and so are the operating costs. However, the attic must be perfectly sealed for the unit to operate properly.

In some cases, power ventilation will be enough to provide you with a comfortable interior environment without having to add air conditioning. If you already have air conditioning, the addition of a power ventilator may reduce the amount of time the air conditioner runs.

The benefits of ventilation:

• An economical way to reduce heat build up in your home

Maintenance:

• Regularly clean or replace both intake and exhaust filters.
  
• For heat recovery ventilators, clean the heat exchanger core annually. If the unit has a condensation drain, clean the drain line to make sure it's open and free flowing. Clean the outside intake and exhaust vents of any debris.
  
• Clean and vacuum vent grills in each room periodically.

back to top

Attic ventilation can make a big difference
If your home seems unreasonably hot in the summer, the real culprit may be the attic. The attics of older homes are often under-insulated and unventilated which can lead to a build-up of air as hot as 54°C (130°F).

Good insulation will not only keep your house warmer in the winter, but cooler in the summer. Remember though, to air seal your attic floor before insulating, in order to separate the attic from the heated part of the house. Air that leaks into the attic through cracks and penetrations can account for substantial heat loss in the winter and can lead to moisture related problems.

With passive attic ventilation, roof vents allow air to circulate and the heat to escape. Adequate ventilation requires a combination of vents located as high and as low on the roof as possible. This type of attic ventilation system includes ridge, roof, soffit, and gable end vents. For maximum air flow, the area of high roof vents should equal the low vent area.

Vents should be located to give good cross ventilation from end to end and from bottom to top of the attic space. Take care to ensure that eaves vents are not blocked by insulation. A contractor can help with advice on proper size vents.

Benefits:

• Proper insulation and venting of your attic improves your home's comfort levels year-round

Maintenance:

• There should be no regular maintenance required once the work is complete

back to top