Attic Ventilation
Attic fans work to reduce heat and moisture from your attic space. The air must be moved quickly enough to prevent heat and moisture buildup. The air movement is enhanced by attic fans crucial at preventing this buildup. However, a barrier between your attic and living space is also necessary to prevent pulling air from the living space. Additionally, several intake points through soffits or gables are necessary to have air exchange for proper attic ventilation.
Heat and moisture can lead to roof degradation, overtaxed HVAC system, mold, wood rot, and in certain climates, ice dams. Excessive heat in your attic is not energy efficient. Consequently, it can create a strain on your air conditioner and increase your energy consumption.
Daily activities in your living space create most of the moisture found in the attic. This warm moist heat easily rises and transfers into the attic space. Furthermore, once in the attic space, condensation can occur. If left untreated, it can lead to mold and wood rot of your structure, and in some geographic areas with heavy snow, ice dams can form.
Attic fans very simply exchange the air in the attic. Specifically, this expels moisture and reduces heat. One of the keys to ventilation in the attic is that the air has to exchange quickly and frequently to keep the temperature from rising. The attic fans work to keep that air moving much faster than through passive ventilation. The fans draw the air from the outside into the attic and then push out the hot or humid air.
Are Attic Fans Effective?
The effectiveness of your attic fan is limited by the type of fan system you install. Attic fans assist with air movement from an intake point, such as your soffits, to the highest exhaust point in your attic. The concept is to remove the hot and/or wet air and replace it with drier fresh air, thus, helping prevent moisture and heat related issues.
Seal, Insulate and Ventilate
In order for your attic fans to be effective, there needs to be a barrier between the attic space and your living space. This barrier specifically limits the transfer of heat and moisture between your living and attic spaces. “A tight, well-insulated house saves energy,” according to Smarter House.
Firstly, ensure proper insulation and sealing are in place to create this barrier. It is an important aspect of your attic ventilation and the energy efficiency of your home. Secondly, consider which type of fan is best for your home.
Key considerations when choosing an attic fan:
- How quickly will the fan exchange the air to reduce the attic temperature?
- Does the fan provide a balanced airflow in the attic? or is it overpowered?
- When will the fans run?
- Does the attic fan sensor measure the air outside?
- How loud are the fans?
- Where are they installed?
- How are they powered?
- Are the fans energy efficient?
Solar Attic Fans
How do Solar Attic Fans Work?
Solar fans tend to be quiet and are an energy efficient attic fan option for removing heat from your attic. A thermostat typically regulates the solar fan to come on in high heat. Some models have a humidistat option. Most solar fans focus only on attic heat reduction. However, it is important to consider how both heat and moisture will be addressed. Moisture becomes more of an issue in colder climates.
Powering Solar Fans
The fans have solar panels that convert the sun’s rays into solar energy. Therefore, they use no electricity. However, some solar fans have the capability of storing some solar energy in a battery backup. Unfortunately, even with a battery backup, longer periods of weather without sun may leave you without attic ventilation.
The solar fan has limitations to consider. First, the fan’s ability to run when solar energy is not present. Secondly, the fan’s inability to consistently and effectively exchange the air. For example, at night the air is typically cooler and may be a better time for the fans to run, but without the sun they are unable to use this beneficial air. Some solar fans will even cut off when shadows from trees or clouds block the sun from the actual solar panel, and they certainly won’t operate with a snow covered roof.
The solar fan can waver in the amount of energy output to spin the fan blades. When the sun is not direct, such as early morning and early evening, the fans slow because they are not receiving full power. These times are often the most beneficial for cooling the attic space, yet these fans will not work without the sun.
Therefore, consider the climate and typical weather patterns before installing solar fans in your home.
Installation of Solar Fans
There is virtually no wiring to this fan since it is not connected to an electric source. Some fans may have a solar panel that can be moved and mounted in an area of the roof that receives more direct sunlight. With the need for sun, these fans install directly onto your roof. Therefore, there is a greater potential for roof leaks.
Electric Attic Fans
How do Electric Attic Fans Work?
Electric fans are regulated by a thermostat, and sometimes a humidistat will be installed as well. However, these sensors are only measuring conditions within the attic space. Without measuring the conditions of outside air, the fan could be running when outside air is not beneficial to your attic space. Unlike the solar fans, electric fans can run at night, cloudy days or any other time when cooling for an attic would be beneficial.
The attic fans tend to be oversized and noisy. Additionally, these powerful fans require a proper barrier. It is important to prevent pulling air from the living space directly into the attic. Also, there tends to be a lack of balanced airflow as the fan is pulling from one location.
The primary focus of an electric attic fan is on reducing heat, but let’s not forget the importance of decreasing moisture in the attic. However, if a humidistat is installed with the attic fan, it can run during the winter months when mold and moisture issues are more prevalent.
Powering Electric Fans
Electric fans are powered by electricity. The fans are often quite powerful using quite a bit of energy. For this reason, the electric fan’s energy efficiency is sometimes brought into question. In theory, the fans reduce your electrical cost, because they reduce the demand of your AC. However, some may argue that the cost to run these types of fans offsets the savings from reduced usage of AC.
Installation of Electric Attic Fans
Electric fans are often installed in gables, but some may be roof mounted as well. Generally, the attic fan is one large, powered fan. This can therefore lead to pulling air from inside the home and lacks the ability for a distributed airflow within the attic space. With traditional electrical wiring, an electrician will install this type of fan.
ATMOX Fans
How do ATMOX Attic Fans Work?
ATMOX is a sophisticated controller that accurately measures the inside and outside conditions of your attic before running its fans. Sensors inside the attic and outside measure temperature and humidity. Then, the controller uses these measurements to determine whether the fans should run to exchange the air in the attic. Therefore, the fans will run only when the air outside is beneficial to replace the inside air with drier fresh air.
Powering ATMOX Fans
ATMOX uses multiple fans to avoid an oversized noisy attic fan. The fans are energy efficient using only 15 watts of power per fan when running. The fans exhaust air using the available intake airflow from the outside to avoid pulling air from the living space. Therefore, these energy efficient fans create a distributed airflow, which is especially important in addressing moisture concerns to avoid winter condensation.
Installation of ATMOX
These fans can be installed in a ridge vent or gable vent without cutting into the roof. Since the roof can remain untouched, there are no concerns for roof leakage due to the installation of these fans.
ATMOX uses low voltage wiring often found in landscape lighting. The ATMOX controller provides power to the fans from one electrical outlet. Each fan attaches to the low voltage wiring to receive power and operational information from the controller. Accordingly, this eliminates the need for an electrician for installation.
Attic Fan Comparison
| ATMOX | SOLAR | ELECTRIC | |
|---|---|---|---|
| Heat Reduction | Yes | Yes | Yes |
| Moisture Reduction | Yes | No | Varies |
| Energy Efficient | Yes | Yes | No |
| Power Source | Electric | Solar | Electric |
| Typical Watts Used | 120-150w | 0w | 500-900w |
| Decibels | 49dB | 30-45dB | 40-70dB |
| Consistent CFM | Yes | No | Yes |
| Measures Outside Conditions | Yes | No | No |
Attic Fan Goals and Priorities
In some ways, all attic fans work in the same manner to exchange cooler and drier air from the outside with the air within the attic. However, choosing the right style of fans for your house will depend on your goals and priorities. For example, are you concerned about moisture or only heat? Go back through the Key Considerations questions above to determine your best attic fan fit.
