The more cool air you lose, the harder your air conditioning unit works and the higher your electricity bill will be. Install blinds, hang curtains or get storm windows made to keep cool air from seeping out. Even mesh screens, on the outside of your home, will help deflect solar radiation. You might even consider replacing old windows that leak cold air and let in heat.
Canadian electricity is cheap at 10 US cents per kilowatt hour, which is reflected in their high average electricity usage. US electricity prices at 0.12 $/kWh are also quite cheap internationally. In India and China they are very cheap. The UK is in the middle at 20 cents. It’s relatively expensive globally but not too bad for Europe, where most countries pay a high share of tax on their power.
You can organize and shop by pricing at YOUR individual usage level, which allows you to shop and compare energy plans based on the rates you’ll actually see appear on your bill, inclusive of taxes and hidden fees. You won’t be misled by the “teaser rates” tied with higher usage levels that many homes never experience, as their usage level never reaches that pricing tier.