The same goes for attic ventilation. It’s essential for reducing moisture and preventing excessive heat.
However, in pursuit of attic ventilation, some people choose to install attic power ventilators. In theory, these are excellent tools for circulating air in the attic and keeping the attic temperature low.
In practice, however, attic power ventilators may not be as useful as we might hope.
In fact, they can be harmful to your energy bill.
What is an Attic Power Ventilator?An attic ventilator is essentially a port where air can escape to the outdoors. While it may seem silly to meticulously cover a home with insulation, only to leave a place for air to escape, the attic vent serves a few important purposes. It allows hot air to escape in the summer, and can also help reduce the chances of ice damage in the winter by allowing a natural flow of outdoor air to ventilate the attic.
While a simple vent is sometimes used to allow for the passive flow of air, it’s also possible to add a powered attic fan, commonly called an attic power ventilator.
Attic power ventilators are mounted to the roof of the home and are connected electronically to a power source and, in most cases, the home’s thermostat.
When connected to the thermostat, they can turn on and off automatically depending on the current household temperature and the specific settings. These fans draw air from the attic and send it outdoors.
In theory, the air is then replaced by outdoor air, creating a healthy cycle of airflow. If the outdoor air is cooler, then it stands to reason that the home will be cooler because of this cycle.
The Issue? What Air is Being Forced Out?There is a potential risk with powered attic ventilators. Because the units forcefully pull air from the attic, they can create depressurization in your home.
It also hard to predict where exactly the new air, which is replacing the air forced out by the ventilator, will come from. It’s expected that the air will come through the soffit vents into the attic space, but that’s not always the case. If your roof has a slope, then it should have a ridge vent at the peak of the roof to naturally allow hot air to flow out of the attic.
Many homes do not have air-tight barriers between the attic and the living space. If the air being forced out by the fan is coming entirely from the outside, then yes, powered attic fans can be extremely effective.
But most experts agree that this is not always the case. What happens more often is the air from the living space of the house comes up to replace the air being forced out of the attic.
This is where the problem exists.
In many cases, the air being pulled into the attic and then out the ceiling is air conditioned air. This means you are spending money (through your utility bill) to cool the air, only to have it expelled by the attic power ventilator.
In some cases, it’s reasonable to believe that an attic power ventilator can increase your utility bill by forcing the A/C to work harder to replace the outgoing air.
Attic Power Ventilators’ Energy ConsumptionWhile the specifics will change with each home, the general consensus is that attic power fans actually use more energy than they save.
Sources such as The Billings Gazette, Energy Vanguard, and Home Power all have articles that essentially say the same thing: attic power ventilators are simply not worth the cost and effort.
In fact, the Home Power article states that a “typical 250-watt fan would use 180 kWh per month if run continuously.” The entire home, however, only uses about 950 kWh per month, so the ventilation system can encompass a significant amount of energy consumption.
What About Solar-Powered Attic Ventilators?There is, however, a popular option for attic ventilation: the solar-powered attic fan.
These units are often less powerful than ones plugged into your home’s system (which could be a good thing) but are generally much easier to install, as you don’t have to run wires to the unit.
However, the issue of an attic ventilator is not where the energy for the fan comes from, but what the unit is doing to your indoor air.
So, while solar-powered units may not be plugged into your home’s electrical system, they are still pulling up cooled air, once again forcing the A/C unit to work harder.
Do Attic Ventilators Effect the Home’s Temperature?In general, it’s widely believed that an unpowered attic ventilation system will result in a cooler home. This appears to be true, as the hot air will naturally flow upward and eventually escape out of the vents.
So, if you’re not running the A/C, then yes, it’s reasonable to assume that a powered or unpowered system could help lower the inside temperature during the summer.
Once again, however, the issue comes when the A/C is being used. When the A/C pumps out comfortably-cool air, the powered ventilation will simply draw that cool air up and push it out the roof.
The A/C, therefore, will maintain a cool home, it will just have to work harder to make it happen.
Attic Power Ventilators and Roof Protection?Another important element of attic ventilation is protection for the roof’s shingle. It’s believed that good ventilation in the attic will help prolong the life of shingles by reducing heat, which maintains the shingles’ quality and durability. Heat in the attic can roast shingles from below, causing them to wear prematurely.
This is another benefit of proper ventilation in the attic, but it appears that unpowered ventilation is enough to control the heat, at least to a level that will help maintain shingles.
Are Radiant Barriers an Alternative?Imagine an attic covered on every square inch with aluminum foil. This is, essentially, a radiant barrier. Radiant barriers are used to reduce summer heat in the attic, with the goal of reducing cooling costs. They are made of highly reflective material (not tin foil) that reflects the radiant heat from the sun.
While they do not provide thermal insulation, they can be effective for reducing energy consumption during hot months.
To be effective, the material must face an air space; you can’t cover them with plywood or sheetrock.
While these materials do not affect air flow (which is the goal of attic powered ventilators), they can be an important addition to the energy-friendly cooling methods for your home.
What are the Risks of Attic Ventilators?There are other risks for attic ventilators that have been assessed by researchers in North Carolina and Florida. Although the article from Home Energy dates back to 1995, it remains an important part for examining powered attic fans. According to the article, powered attic fans can create excess moisture, structural problems, and combustion safety in a home.
The research concluded that if a powered attic ventilator will be used, there must be a good air barrier between the living space and the attic. It also concluded that a bigger attic fan is not always better, as pushing out more air should not always be the goal.
What if my Attic is Hot?This brings up to an important part of the discussion. Does it really matter if your attic is hot?
If you have good insulation between the attic and the living space, the answer is no.
However, if you have ductwork running through your attic, the ductwork should be insulated as well; otherwise the heat in the attic could warm the air moving through the ducts.
Yes, heat on the shingles can wear them down, but rarely will the heat be so high and prolonged that it causes significant premature damage to shingles or roof sheathing or materials.
Whole House FansIf you are looking to enhance the ventilation in your home for any reason, a better option may be a whole house fan. These systems are used as an alternative to AC units (and can complement the A/C) when the outdoor temperatures cool down.
They can be especially effective in the spring and fall months or if you live in a drier area where temperatures cool down at night.
While the extreme heat of summer and frigid chill of winter will call for different measures, you may be able to get the comfortable air and attic circulation you want without the negative effects of an attic power ventilator.
Enhance Your Home’s Indoor Air Quality with OransiIf you want more information on indoor air quality and the benefits of circulation, contact Oransi’s friendly team today.
We’ll work with you to make sure you have everything you need for a healthy home, including quiet and efficient air purifiers with advanced HEPA filters.