As spring draws to an end, forward-thinking consumers are already preparing to install air conditioning to combat the hot and humid summer days ahead. But is this really the only answer to the problem? One thing is sure: your electricity bill is going to take a big hit if you plan to have an air conditioner do all the work to cool your home.
Keep the heat from getting in
Before you run to the store to pick out an air conditioner, it’s worth looking at how the heat gets into your home. Alternative methods, including so-called passive cooling, may well improve the situation and bring you the comfort you’re looking for.
Exterior cladding – Dark colours absorb the sun’s rays. In fact, up to a third of the heat captured by a building can be transferred to its interior by conduction.
Tips: If you are thinking of resurfacing your roof or changing or repainting the exterior wall covering, choose light colours, which will reflect a large part of the heat. If you are good at gardening, you can consider a green roof or a vertical garden (living wall), both of which make very effective sunscreens.
Windows – They can make your house feel like an oven, especially if they face south or southwest, in which case they are responsible for about 40% of the sun-generated heat in your home.
- Install opaque, light-coloured blinds or curtains, as close as possible to the windowpane.
- Choose windows equipped with insulating glass and “Low-E” film, which acts as a protective shield against the warm rays of summer sunshine.
- Install sun-control films in your windows. They can reduce heat induction by up to 75% and block virtually all ultraviolet radiation, which causes furniture and coverings to fade.
- Create shade by adding awnings or shutters to your windows.
- Plant hardwood species that grow tall, because the sun’s angle is at its highest in summer.
- Extend the roof overhang, if possible.
Thermal insulation – A poorly insulated house is just as uncomfortable, and wastes as much energy, in winter as in summer. Attending to this problem, at any time of the year, is good for your wallet!
Tips: Add insulation in the attic and make sure it is properly ventilated. More than a third of the heat that enters your home comes through the roof.
Concrete and asphalt – Traditionally used for surfacing driveways, porches and paths, as well as landscaping, these materials behave like open-air radiators whenever the sun comes out.
Tips: If you are planning a new landscaping job, avoid using concrete or asphalt on surfaces directly exposed to the sun. Use materials that absorb less radiant heat, and include green islands and flowerbeds in your landscape design. You can also install awnings, hedges or other architectural elements that can provide beneficial shade in critical areas.
Natural ventilation – Air that is allowed to circulate provides a cooling sensation at all times, and also allows heat to escape to the outside.
- Opt for casement windows, which have the advantage of drawing air into the house.
- Plant hedges or install trellises adorned with vines in strategic areas to direct breezes toward open doors and windows.
- Open your doors and windows wide on the windy side of the house and leave them slightly ajar on the opposite side. Leave all inside doors fully open.
- On days where there is no wind, force the air down below to come up. Open the windows in the basement, where the air tends to be cooler, as well as those on the top floor, where it is usually warmer. Draw the blinds and curtains during sunlight hours. Then, in the evening, open doors and windows again to let cool air in and “store” it.
Heat-generating appliances – These are found all over the house, but you can easily limit their use during periods of particularly hot weather.
- The watchword for using your stove, dishwasher and clothes dryer during a heat wave is “minimum.” Wait until the evening, when the air in the house has cooled down somewhat, to run these appliances. Drying your clothes outside is also a great idea.
- Cooking in the microwave or on the barbecue won’t create additional heat inside – and allows you to vary the menu!
- Choose compact fluorescent bulbs; they generate 90% less heat than incandescents. Still, don’t forget to turn them off when they’re not needed.
- If you return from a fairly long car trip, don’t park in the garage right away: the hot engine will quickly heat up the garage and, in turn, the house, if part of it is located immediately above.
- Find a way to block the heat given off by your water heater and washer-dryer room so that it doesn’t travel to the rest of the house
Make sure you get enough air
When passive cooling methods aren’t enough to ensure your comfort, move on to the next step: helping the air to circulate!
Ceiling fans – Fans won’t cool a room, but they move the air around, creating the pleasant feeling of a refreshing breeze. In summer, ceiling fan blades should rotate to push air downward. They are most efficient if installed 2 to 3 metres (7 to 9 feet) above the floor. Their energy cost is negligible: between $0.08 and $1.50 per month. An air conditioner, on the other hand, will increase your electricity bill by anywhere from $6.75 to $40.50 for the same period!
Pedestal fans – These types of fan are just as energy efficient as ceiling fans, and available in a wide range of portable models. Here’s a trick for really hot days: place a tub of ice water in front of the fan. You’ll have cool air at practically no cost!
Air extractors – Your bathroom fan and range hood can work wonders when it comes to ridding your home of humidity and stale air, especially if your air conditioning or air exchanger system is on and the doors and windows are closed.
Portable dehumidifiers – The relative humidity of ambient air is probably the most unpleasant thing about hot summer days. A portable dehumidifier can be a valuable ally on the comfort front: its use, however, must be limited to a single room, which must be closed off from the rest of the house and from the outside – where the air in summer tends to be just as humid as it is indoors.
When all else fails: use an air conditioner
The heat sets in, the air is muggy and you’re having trouble sleeping… Suddenly, you don’t mind the high cost of running an air conditioner. But be warned: the prices of these appliances tend to vary as much as their energy efficiency. Following is some advice to help keep you from “hitting the boiling point” when your electricity bill arrives in the mail.
Check the EnerGuide label – It provides information on the unit’s performance. The higher the SEER (Seasonal Energy Efficiency Ratio), the less energy the device will consume.
Look for the Energy Star symbol – Products with this certification can mean energy savings of almost 15%. To be Energy Star-approved, an air conditioner must have a SEER of at least 14, but there are some models on the market with a SEER as high as 21. You should also consider buying a programmable Energy Star thermostat to maintain a constant temperature in your home and save energy.
Check the dimensions and power – Surprising as it may seem, a smaller unit that runs for longer is more efficient than a more powerful air conditioner that stops and starts often. With the right-sized air conditioner, relative humidity can be maintained at 30% to 50%, which will improve air quality along with your comfort.
Make sure it has the best possible working conditions – Don’t put a TV or lamps in the vicinity of the thermostat: the heat they give off can trigger the air conditioner when it isn’t actually needed. Set the thermostat to 24°C (75°F) – every degree below that setting results in a surplus energy demand of around 3 to 5%. Clean the air conditioner’s filter every month and replace it as needed. This can reduce energy consumption by 5 to 15%.
Install the compressor away from direct sunlight – Ideally, you should install the compressor on the north or east side of the house, and ensure it is in the shade of a bush or screen. Make sure, however, that you don’t hinder the air circulation necessary for its proper operation.