To cool a home, you need to take advantage of active and passive cooling strategies. Active strategies require electricity to operate correctly. Running your AC unit falls into this category. Passive strategies, as you might have guessed, do not require electricity. Proper shading falls in this category. By using shade strategically around your home, you can improve the performance of your AC unit and save money on your cooling bills.
Beating Heat Gain with Awnings
Heat gain is the term used to describe how your home heats up during the day. Most of the heat your AC unit has to contend with comes from the sun in one way or another. For example, 30% of the heat gain in your home comes through your windows. You have an opportunity here to make your AC unit's job easier in that if you block the sun from shining through your windows, you can keep your home cooler. Window awnings will shade your windows without blocking off your view of the outside worlds. If you think awnings are just clunky canvas structures you find on older buildings, there are a ton of modern awning designs that can actually improve the the looks of your home and still reduce your cooling bills by at least 17%.
Evapotranspiration—Trees Are Good for More Than Shade
On a 90 degree day, it is common for an attic to reach temperatures of at least 125 degrees. Some of that heat will seep into your home and cause your AC unit to work longer and harder than it should. You can improve your insulation and use attic fans to prevent that heat from entering your home, but it is important to understand why your attic heats up in the first place. The sun beating down on your roof heats up your shingles, and they, in turn, heat up your attic. Thus, by planting shade trees, you can prevent the sun from reaching it in the first place and keep your roof up to 45 degrees cooler than it otherwise wood be. Shade can help, but trees will also cool the air through a process known as evapotranspiration. As water vapor escapes tree leaves, it absorbs heat from the surrounding air, and this cooler air settles onto your house and yard, keeping the air up to 9 degrees cooler than it would be without trees.
As you can see, shade can play a supportive role for your AC system. If you can keep your home cooler to begin with, your AC system doesn't have to run as often and hard as it does on a super hot day. This saves wear and tear on your system and reduces your cooling costs. Passive cooling may not be enough to keep your home comfortable on its own, but that doesn't mean it doesn't have a place alongside a modern air conditioning system.