In the summer heat, our air conditioning systems work tirelessly to keep our homes cool and comfortable, but their energy consumption can send electricity bills through the roof.
But what if there are ways to mitigate this?
Can attic ventilation save cooling costs?
With sufficient intake and exhaust vents in the roof, attic ventilation can save cooling costs. Proper ventilation will reduce attic heat and remove some of the burden on the AC system, potentially saving energy costs. However, using electric ventilation systems could negate potential savings.
Whether you're redoing your roof or building a new home, understanding the impact attic ventilation has on your home's ability to breathe is essential. As you install the necessary vents in the new roof, you can expect optimal temperatures and air circulation in your attic, which can lessen your energy bill and ensure your roof's long-term health.
Can Attic Ventilation Make a Difference to Your Cooling Costs?
Approximately 75% of US homes have air conditioning systems installed, and research indicates that families spend 35% - 42% more on their energy bills when using ACs to cool their homes. In today's harsh economic climate, finding ways to decrease these costs is essential.
Attics trap the hot air.
If you've ever wondered why your attic is unbearably hot, it's primarily due to a lack of ventilation, causing hot air to stay trapped inside. These often-neglected spaces absorb heat in different ways, and if there is nowhere for it to escape, temperatures can reach up to 50°F hotter than they should be. Attics can trap the heat in the following ways:
Poorly ventilated attics affect home temperatures.
If you have a poorly ventilated attic with a substantial heat buildup, the heat will transfer to the living areas inside your home, forcing your AC to work harder. Of course, this uses extra energy, upping the costs of your energy bill.
When you consider that cooling forms 6% of your energy bill, it becomes evident that poor ventilation can cause an unnecessary waste of money.
Proper ventilation can drop attic temperatures.
Having a well-ventilated roof is preferable when you move into a new home, but it doesn't always happen. But if you need to replace your roof or are building a new home, building a ventilation system into your attic can make a significant difference in keeping your house cool.
Attic ventilation works on the simple principle of convection. Intake vents draw the fresh outside air into the attic, while the exhaust vents expel the hot air. The result is an attic temperature that doesn't force the AC to work extra hard.
Although it might seem counterintuitive to ventilate the attic in an insulated home, fresh air must flow through it throughout the year. In the summer, proper attic ventilation reduces the heat. In winter, it provides an escape for the moist, warm air seeping in from below.
Good attic ventilation mainly benefits your energy bill in the summer, but during the winter, proper attic ventilation will prevent ice dams from forming on your roof. These can damage the roof, leading to expensive repairs, and can facilitate mold and mildew growth inside.
How to Ventilate Your Attic to Save Cooling Costs
Attic ventilation is divided into two main categories: passive (or natural) and active. If done correctly, passive ventilation is the most cost-effective way to circulate the air in the attic and reduce the excessive heat.
Passive ventilation depends on natural forces.
Passive ventilation depends on natural forces such as convection and wind to circulate the air in the attic and expel the hot, humid air when it reaches the exhaust vents. Working on the principle that hot air naturally rises, professionals will install intake vents at the roof's lowest point and exhaust vents at the peak.
For passive ventilation to be effective, you must install enough vents to ensure balanced airflow. Most building codes recommend 1 square foot of vent per 300 square feet of floor area. In many older homes, the number of passive vents built into the roof is insufficient for adequate ventilation, and cooling costs can soar rather than decrease.
Another factor to consider with passive ventilation is whether the vents in your roof are open. Sometimes, when homeowners insulate their houses, they unwittingly close up soffit vents or their equivalent passive cousins. While the vents are still present, they are blocked and unable to facilitate the necessary ventilation. Examples of passive roof vents include soffit vents, gable vents, dormer vents, static or turtle vents, gooseneck vents, and ridge vents without baffles.
Active ventilation uses mechanical means.
Active ventilation uses mechanical means to pull fresh, cooler air into the attic and force the hot air out through the exhaust vents. They use blades, motors, or turbines to circulate the air. Examples of active ventilation systems include the Whirlybird and ridge vents with baffles (plastic flaps that open to allow warm air to escape).
Some ventilation systems, such as power roof vents and attic fans, use electricity to cool the attic. Power roof vents sit near the roof's ridge and suck out the hot attic air. They are very effective, but the energy consumed to run the motors may negate the energy saved by their use.
Final Thoughts
Attic ventilation is essential for your roof's health and can save on cooling costs. However, we must add some caveats to this statement.
If you install sufficient passive vents, you will enjoy efficient ventilation and savings on your energy bill. Using electricity to power mechanical vents may nullify these savings, so it's best to seek professional help for long-term, cost-effective attic ventilation. (Related article: Explained: Active, Passive, and Mechanical Roof Ventilators)