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Alternative-Heating-Info.com
Radiant Attic Barriers (Eligible for 30% Energy Tax Credit)
Research done by the Florida Solar Energy Center (FSEC) shows an attic radiant
barrier can save 10% to 15% on the heating and cooling portion of electricity costs in a
typical Florida home. This would translate to annual savings of 3% to 6% on the entire
electric bill.
The installation of an attic barrier is relatively simple making it an ideal DIY project.
Basically you have two installation choices: Over the attic floor, or between the rafters
supporting the roof. Of the two, over the attic floor is the easiest. Simply roll out the
sheets, shiny side up, from one end of the attic to the other overlapping the sheets as
you go along.
No stapling is required because you want the reflective sheets to float freely above
the insulation allowing an air space underneath the barrier as well as above. If the
barrier is compressed against the underlying layer of insulation it will lose its
effectiveness.
One concern frequently voiced with "over the attic floor" installations is dust
accumulating on the surface of the barrier and degrading its effectiveness over time.
But some attics just aren't as dusty as others; it's really up to you.
In any case, take a minute to spend some quality time with your attic and have a look
around. You may have forgotten how much stuff is up there rendering an over the floor
installation ineffective as well as impractical.
If you decide to proceed with the over the floor application make sure you purchase a
perforated barrier specially designed to allow moisture to pass through, and be careful
not to cover kitchen and bathroom vents or recessed lights.
barrier can save 10% to 15% on the heating and cooling portion of electricity costs in a
typical Florida home. This would translate to annual savings of 3% to 6% on the entire
electric bill.
The installation of an attic barrier is relatively simple making it an ideal DIY project.
Basically you have two installation choices: Over the attic floor, or between the rafters
supporting the roof. Of the two, over the attic floor is the easiest. Simply roll out the
sheets, shiny side up, from one end of the attic to the other overlapping the sheets as
you go along.
No stapling is required because you want the reflective sheets to float freely above
the insulation allowing an air space underneath the barrier as well as above. If the
barrier is compressed against the underlying layer of insulation it will lose its
effectiveness.
One concern frequently voiced with "over the attic floor" installations is dust
accumulating on the surface of the barrier and degrading its effectiveness over time.
But some attics just aren't as dusty as others; it's really up to you.
In any case, take a minute to spend some quality time with your attic and have a look
around. You may have forgotten how much stuff is up there rendering an over the floor
installation ineffective as well as impractical.
If you decide to proceed with the over the floor application make sure you purchase a
perforated barrier specially designed to allow moisture to pass through, and be careful
not to cover kitchen and bathroom vents or recessed lights.
When you install the barrier between, or along the rafters, the gable ends should also
be covered. If the attic roof extends over the garage, the Dept. of Energy recommends
extending the barrier by 8 feet over the garage to achieve the same effect as covering
the gable end. However, covering the gable ends is not necessary if the barrier is
installed over the attic floor.
Radiant barrier foil is not insulation per se and therefore has no inherent 'R' value
rating.
Prices for radiant barriers vary by function and durability (tensile strength). Perforated
barriers, and high tensile strength barriers (80.4 lb/in) both sell for around $0.15 per
square foot. Standard strength barriers (14.1 lb/in) are slightly less at $0.12 per
square foot.
The cost an attic barrier can be further reduced with the new Energy Tax Credits. The
maximum credit is now 30% of the cost of the material up to $1,500. Installation is not
covered.
be covered. If the attic roof extends over the garage, the Dept. of Energy recommends
extending the barrier by 8 feet over the garage to achieve the same effect as covering
the gable end. However, covering the gable ends is not necessary if the barrier is
installed over the attic floor.
Radiant barrier foil is not insulation per se and therefore has no inherent 'R' value
rating.
Prices for radiant barriers vary by function and durability (tensile strength). Perforated
barriers, and high tensile strength barriers (80.4 lb/in) both sell for around $0.15 per
square foot. Standard strength barriers (14.1 lb/in) are slightly less at $0.12 per
square foot.
The cost an attic barrier can be further reduced with the new Energy Tax Credits. The
maximum credit is now 30% of the cost of the material up to $1,500. Installation is not
covered.
The second installation option is
with the reflective side facing
down from the rafters.
Diagram #1 illustrates between
the rafters. Diagram #2 illustrates
rafter to rafter horizontally across
the attic.
Of the two, across the rafters
would obviously be easier to
implement.
In either case make sure the
shiny surface is facing down
towards the attic floor.
Now you have to be asking
yourself, "How can the foil side
work if it is facing downwards?"
It may seem counterintuitive, but
a radiant barrier works just as
well with the reflective side facing
toward the roof or away from it.
This is because a radiant barrier
not only REFLECTS INFRARED
ENERGY, it also does not EMIT
RADIANT HEAT.
These two qualities are known as
Reflectivity and Emissivity and
work together as one; not
exclusive of each other.
with the reflective side facing
down from the rafters.
Diagram #1 illustrates between
the rafters. Diagram #2 illustrates
rafter to rafter horizontally across
the attic.
Of the two, across the rafters
would obviously be easier to
implement.
In either case make sure the
shiny surface is facing down
towards the attic floor.
Now you have to be asking
yourself, "How can the foil side
work if it is facing downwards?"
It may seem counterintuitive, but
a radiant barrier works just as
well with the reflective side facing
toward the roof or away from it.
This is because a radiant barrier
not only REFLECTS INFRARED
ENERGY, it also does not EMIT
RADIANT HEAT.
These two qualities are known as
Reflectivity and Emissivity and
work together as one; not
exclusive of each other.
| Diagram 1. Between the rafters vertical installation |
| Diagram 2. Rafter to rafter horizontal installation |
The attic radiant barrier was originally
designed as a means to reduce attic heat in
southern climates where air conditioning is
prevalent.
Lowering the temperature in your attic
suppresses heat gain on lower floors and in
turn reduces the cooling load on the air
conditioning system.
A reduction in the cooling load means the air
conditioner requires less energy to provide
the same amount of cooling; saving you
money.
designed as a means to reduce attic heat in
southern climates where air conditioning is
prevalent.
Lowering the temperature in your attic
suppresses heat gain on lower floors and in
turn reduces the cooling load on the air
conditioning system.
A reduction in the cooling load means the air
conditioner requires less energy to provide
the same amount of cooling; saving you
money.
