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Energy Savings
"If you are not using SIPs as your core building material
you are not serious about energy efficiency."
Michael Morley, Builder & Author - "Building with
Structural Insulated Panels"
Energy Payback
There are five reasons foam-panel homes should have lower heating and
cooling bills than homes insulated with common wall and ceiling insulation
materials:
- Structural Insulated Panels achieve thermal ratings of between R-4 and
R-7 per Inch; batt and loose-fill materials are about half that.
- With less wood, panels reduce thermal bridging (the transfer of heat
into or out of a structure through a solid piece of lumber). A 16-foot SIP
wall section with one 3 x 4-foot window contains 5 percent wood and 95
percent Insulation. The same wall framed with 2 x 4s 16 o.c. has 20
percent wood and a variable amount of insulation.
- If not installed properly, batt insulation is susceptible to voids.
Batts are either jammed into narrow cavities, improperly split around
wiring or around electrical boxes, or cut too short or too long. In some
remodeling jobs, insulation is removed, but not replaced. When used with a
trussed roof system, batts won't cover up the bottom chords, allowing heat
to transfer directly from the interior of the house into the attic area in
the winter and from the attic into the house in the summer. A solid foam
panel eliminates these problems.
- Any air moving within a conventionally insulated wall or ceiling
decreases the energy performance of batt insulation. When properly sealed,
foam panels do not allow air movement.
- Depending on proper installation and effective sealing of joints and
openings, Structural Insulated Panel (SIP) construction lends itself to
tighter-than-average construction. This is especially true when SIPs are
used for both walls and ceiling because the systems are engineered to
connect to each other easily and tightly.
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| R Value |
Panel Thickness |
Weight (PSF) |
| 16.87 |
4.50" |
3.31 |
| 25.60 |
6.50" |
3.47 |
| 33.20 |
8.25" |
3.61 |
| 41.90 |
10.25" |
3.78 |
| 50.60 |
12.25" |
3.95 |
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CASE STUDY 1
Place: Watertown, S.D.
Heating degree days: 9,000
Size of home: 1,040
square feet with a full basement, identical floor plans
Energy source: Natural gas, forced-air furnace |
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Conventional frame |
Panel frame |
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| Walls |
6' fiberglass batts with 1" foil
sheathing; R-24 |
5"EPS-core panels, R-24 |
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| Ceiling |
12" fiberglass; R-38 |
71/2" EPS-core panels, R-32 |
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Heated
area |
Main floor |
Main floor and basement |
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Heating bill
Jan.-March |
$263 |
$85 |
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| CASE STUDY 2 Place: El Jebel,
Colo.
Heating degree days: 7,635
Size of home: 1,336 square feet
Heating source: Electric baseboard; HRV |
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Conventional 2 x 6
frame |
Panel frame |
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| Walls |
51/2" fiberglass batts plus
1/2"exterior Insulated, R-22 with airtight drywall (5/8") |
R-22 |
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| Ceiling |
Fiberglass batts, R-38 (R-30 in
slope) |
R-38 |
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| Heated area |
Whole House |
Whole House |
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Heating bill
Oct.-Dec. |
$450 |
$112 |
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| CASE STUDY 3 Place: Ludlow, Mass
Heating degree days: 5,600
Size of home: 2400 square feet
Heating source: Electric |
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Conventional 2 x 6 frame |
Panel frame |
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| Walls |
51/2" fiberglass
batts, R-19 |
R-25 |
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| Ceiling |
9"Fiberglass batts, R-30 |
R-33 |
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| Heated area |
Whole House |
Whole House |
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Heating bill
Oct.-Dec. |
$131/mo |
$30/mo |
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Building 1 |
Building 2 |
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2 x 6 Stick Frame |
6.5" Precision Panel |
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December 1997 |
$158.92 |
$38.45 |
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January 1998 |
$176.46 |
$64.85 |
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February 1998 |
$112.85 |
$29.36 |
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March 1998 |
$72.81 |
$22.07 |
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Totals |
$521.04 |
$154.73 |
| Savings
over a 4 month period = $366.31 The walls of an Idaho
State Liquor Store in Nampa, Idaho are 6.5" thick (R 25.6) and
9' high. Most panels measured 8' wide x 9' high. The total square
footage of this building is 2,990 square feet and the walls were
installed in one day. .
According to the Idaho State Liquor Dispensory, the
building saves them operating expenses every month. There is a similar
building located approximately 10 miles away in Caldwell, Idaho that has
a total of 3,010 square feet and was framed using 2 x 6 studs at 16" on
center. Above is the comparative energy costs for the (2) buildings
during the winter of 1997 / 1998: |
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For further independent evidence, a
recent study of R-value of walls was conducted by the
Oak Ridge
National Labs (for complete stats check here) . Researchers here found
that a 4" SIP wall outperforms 2" x 4" stick construction, and even edges
out 2" x 6" construction in terms of thermal performance. Our 6" panels far
exceed any conventional construction methods in both R-Value and air
infiltration tests. |
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