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Sources such as the billings gazette energy vanguard and home power all have articles that essentially say the same thing.
We closed off eliminated the ridge vents and installed powered vents on thermostats.
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Posted by allison bailes on september 10 2020.
However as a very old builder 70 years i have known cases where roof mounted attic fans have helped tremendously where the roof is a full hip and the ratio of ridge vents to soffit vents was way out of whack.
The problem is solar power attic fans are basically worthless as far as real cfm ratings go.
Here in the southeastern us open cell is most often the spray foam of choice.
A standard a c powered fan using 400w to get 1200cfm is only 3cfm per watt.
During workdays would leave air conditioner off when leaving in the morning.
Does anybody actually believe that a 20 watt motor can move 800cfm of air blowing into a solid dome.
Gable fans fit into the gable vent and can be set to operate only within a preset temperature range.
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They seem to be about the only people that are getting 40cfm per watt.
Temp 92 f at 5pm.
David butler optimal building systems.
Energy vanguard llc 533 west howard avenue suite e decatur ga 30030.
After attic fan installation ac still off during day.
An attic that s brought inside the building enclosure is a beautiful thing.
This is most often done with spray polyurethane foam spf insulation either open cell or closed cell.
Many are solar powered and require no other wiring so they don t cause any additional charges on your electricity bill at all.
In fact the home power article states that a typical 250 watt fan would use 180 kwh per month if run continuously.
The attic fan kept my house cooler by 8f compared to pre fan installation days.
Temp 84f at 5pm.
This was observed on numerous days following the installation.
Understanding manual j occupant loads.
Attic ventilation fans also tend to be quite energy efficient in terms of their own operation.
Yes using fans to put positive pressure in the house would eliminate pulling conditioned air into the attic but if the ceiling has leaks you ve now turned the problem from exfiltration to infiltration and are pushing hot attic air into the house there s also still the problem of using all that power for something that s not necessary.
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Attic power ventilators are simply not worth the cost and effort.
