October 12, 2021
A burning hot attic is one of the most common problems homeowners face in the summers. A hot and stuffy attic can make your entire house unbearable and even cause long-term damage to the structure. Many homeowners see attic ventilation fans as a possible solution.
However, before buying any attic cooling equipment, there are a few factors to consider, such as the noise level of any equipment you use. If you have been thinking of taking the plunge and installing one, read ahead to know whether it is the right choice for you.
What Is an Attic and Why Does It Get So Hot?
An attic is a space directly below your roof and above the ceiling of your top floor. Though it is usually uninhabitable, you can convert it into a room after remodeling it with respect to current building codes. During summers, when direct sunlight hits your home, the roof easily heats up. This heat is then transferred, through conduction, to the attic sheathing and other structural components. These structural components then radiate heat as well, which heats all the items in the attic and the surrounding space.
Why Does an Attic Need Ventilation?
The attic plays an integral part in regulating the temperature of the entire house. A sweltering attic will heat the top floor of the house and lead to increased energy costs. Moreover, attics often contain electrical wiring, plumbing pipes, exposed framing, heating ducts, etc. An extremely hot attic can damage all this equipment and shorten its lifespan.
How Attic Ventilation Fans Work
Attic ventilation fans take advantage of the fact that hot air rises while cold air sinks. They push out hot air that has risen to the top while drawing in cold air from the outside, which slowly cools the attic.
Types of Attic Ventilation
Attics are mandated by law to have some sort of ventilation. This is usually of three main types:
- Non-Mechanical Attic Ventilation
Non-mechanical attic ventilation consists of intake vents, which draw in cool air from the outside, and exhaust vents that allow hot air to escape from the top.
- Electrical/Solar Attic Fans
Electrical/solar attic fans are typically more powerful than passive ventilation systems. They are quicker at replacing hot air with cold air; however, they only work correctly when there is adequate passive ventilation.
- Whole House Fans
Whole house fan systems pull cold air throughout the house and are a good solution for milder climates.
Benefits of Attic Ventilation Fans
Attic ventilation fans offer numerous advantages:
- Prevent Ice Damming
During the winters, conditioned warm air can leak into the attic and cause the snow on the roof to melt. When this snow refreezes, it turns to ice on the roof edge.
This ice on the roof edge acts as a dam, preventing the rest of the snow from falling off. As a result, snow on the roof can damage roofing materials and lead to mold growth. A properly insulated and ventilated attic will help prevent ice damming.
- Improved Ventilation Cools the House
A hot attic also heats up the top floor. A warmer top floor can lead to discomfort and higher energy costs. Due to the heat radiating from the attic, your air conditioners must work harder to cool the top floor, causing wear and decreasing their lifespan. A properly ventilated attic will cool down the entire house and reduce energy usage.
- Prevent Mold Growth
Trapped air and heat in the attic can cause condensation. Trapped moisture due to poor ventilation, combined with darkness and a food source such as wood, can lead to mold growth.
Mold damage can cost as much as $10,000 and is not covered by most insurance carriers. An attic ventilation fan allows the circulation of fresh air, which prevents mold and protects your wallet.
- Can Increase the Lifespan of Roofing Materials
Most roofing shingles are of asphalt, which is derived from crude oil. When your attic gets too hot, it can overheat the shingles and prematurely age them. A well-ventilated attic will keep your roof looking brand new for longer.
Drawbacks of Attic Ventilation Fans
Despite their numerous benefits, attic ventilation fans are a hotly contested topic among homeowners because of some significant disadvantages.
- Carbon Monoxide Poisoning
Attic ventilation fans can remove too much air and create negative air pressure. Negative air pressure mainly occurs when there isn’t sufficient passive ventilation.
For example, if the fan cannot pull air through the soffit/intake vents, it will pull air through gaps in the attic floor. When this occurs, attic fans can pull dangerous combustion gases from furnaces or water heaters into the house.
- Can Cause Loss of Conditioned Air
Similarly, attic fans can also pull in conditioned air from the living space when there is negative air pressure. Loss of conditioned air can warm up the entire house and increase energy costs.
- Faster Air Exchange Does Nothing to Combat the Radiant Heating Process
Though attic ventilation fans increase the air exchange rate, they cannot prevent the sun’s rays from heating the roof. During the height of summers, a faster air exchange rate is often not enough to cool the attic because of the intense heat from the sun.
Attic fans work by pulling cool air in and pushing hot air out. Unless the outside air is significantly colder, attic ventilation fans will not reduce the temperature by a lot.
- Roof Leak Risk
When installing an attic fan, there is always the risk of a roof leak. Most attic fans are not installed to prevent water intrusions during extreme weather. Having an expert install your fan and regular maintenance of roof penetrations can reduce the risk of water intrusions. A gable fan also reduces the risk of water intrusions as it is on the side of the roof.
Enhancing the Efficacy of Your Attic Ventilation Fan
An attic ventilation fan has some advantages; however, on its own, it is not enough to cool the attic sufficiently. There are some other things you need to consider to improve the performance of your attic ventilation fans.
- Radiant Barriers
Install radiant barrier sheets between the rafters to prevent the sun’s heat from warming up the roof.
- Adequate Insulation
Install additional insulation to prevent heat from entering in the summers and leaving in the winters.
- Passive Ventilation
Your attic ventilation fan will not work as it should unless there is sufficient passive ventilation. Make sure you have enough intake and exhaust vents, and they are unobstructed. You can read more about passive ventilation and roof vents here.
What to Do if Attic Ventilation Fans Are Not Meeting Your Needs?
If attic ventilation fans cannot cool your attic sufficiently, you will do well with a ductless air conditioner. A ductless air conditioner, such as a mini-split, in your attic, is an effective cooling solution, especially if you also use it as a living space. If you are worried about costs, you can use a smart AC controller to reduce energy usage.
Attic ventilation fans have many advantages and disadvantages. However, to reap their full benefits, there are many things you have to keep in mind. Used alongside adequate insulation and passive ventilation, they are a viable solution for preventing mold growth, damage to roofing materials, and stuffiness.