Energy Payback

"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"

There are five reasons foam-panel homes should have lower heating and cooling bills than homes insulated with common wall and ceiling insulation materials:

1. Structural Insulated Panels achieve thermal ratings of between R-4 and R-7 per inch; batt and loose-fill materials are about half that.

2. 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.

3. 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.

4. 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.

5. 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.

Energy Tables

The walls of this Idaho State Liquor Store in Nampa, Idaho (pictured above the tables) 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. The General Contractor on this project was Sage Construction of Caldwell, Idaho.

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. Below is the comparative energy costs for the (2) buildings during the winter of 1997 / 1998: