Solar Attic Fans
Save Energy And Protect Your Roof
A solar powered attic fan is an efficient and cost effective way to reduce your energy
use and protect roof structures from damage caused by the build-up of heat and moisture.
Most attics are vented passively, that is with openings but no forced air flow. In
many cases this is not enough to prevent heat and moisture build-up.
Solar attic ventilation fans are now available that use a small solar panel to power an
exhaust fan from sunrise to sundown every day.
In summer, attic temperatures can easily exceed 160 degrees. This trapped heat
transfers down to your living space and makes it uncomfortably warm and/or increases cooling costs. Adding more
insulation can actually make things worse because the insulation traps the heat.
Also, an inadequately vented attic can shorten the life of asphalt shingles because
it allows the roof decking to overheat.
In summer, solar attic fans are a huge benefit because they provide forced air
movement through your attic to:
- reduce heat build-up
- reduce air conditioning costs
- extend the life of your asphalt shingles
In winter, if heat is trapped in the attic due to inadequate ventilation, it
can melt snow on the roof. It runs down to the eaves where it refreezes, creating a dam of ice. Further snow melt can
back up under your shingles or whatever covers your roof, wetting insulation and perhaps even damaging drywall inside
the house. Damage from this can be extensive and very costly to repair.
We were mystified one winter when the light fixture in our laundry room started to fill
up with water. Logic dictated that there must be water above the ceiling to run down into the light, and a trip
up the ladder to the roof showed us where it came from.
An ice dam had formed at the eave and water had backed up under the steel roof,
soaking the insulation on top of the laundry room ceiling. We hadn't noticed it from outside because it all
happened under the snow where it wasn't easily seen. What a mess that was!
During cold weather, moisture in the attic can be even more damaging than heat.
Moisture finds its way into the attic via small air leaks around light fixtures and exhaust fans (of course if you
downloaded our free report about sealing air leaks you'll know how to minimize that problem).
If the moist air is not moved out of the attic quickly, condensation will form on
structural components and the underside of your roof, encouraging the growth of mold, mildew and rot. Moisture can also
infiltrate your insulation, decreasing its insulating value.
Over time, the insulation may become saturated leading to fungal decay of the ceiling
joists.
In winter, a solar attic ventilation fan protects your home because it:
- prevents heat build-up
- prevents moisture build-up and condensation
- protects your insulation
Solar attic fans keep your attic cool and dry with no operating costs. They're
designed to run even in less than ideal solar conditions and are not affected by wind, rain or hail.
In the summer of 2007, Solatube International, Inc. introduced its Solar StarŪ
Conversion Kit (pictured below in various applications) to boost performance of passive vents or transform energy-consuming attic fans to
solar powered attic fans. You can find them at www.solatube.com.
A couple of precautions before installing a solar powered attic fan - because
solar attic fans are so efficient, they can draw air through any openings between your living space and your attic
if there is not enough enough air entering the attic directly from outdoors. This could actually increase your energy
use in winter if you're heating air only to have it drawn up into the attic and exhausted.
Also, the risk of moisture problems in the attic is increased when air is drawn from
the house.
Even worse, in situations where there is not enough outside air entering the attic
and there is substantial air leakage between the living space and the attic, there is a risk that the fan can actually
reverse the air flow up vents and chimneys, exposing your family to toxic byproducts of combustion.
So, before you install a solar powered attic fan:
- seal air leaks between living space and attic
- ensure adequate air enters the attic from outdoors
If you don't know how to find and seal the air leaks in your home, you can find out
by downloading our free report.
