This means drafts don't stand a chance and a typical room with 4" SIP walls used less heating energy than a typical stick built room. The testing protocol used allowed the two rooms, one stick built and one with SIPs, to be depressurized 15 to 50 pascals of pressure.

Oak Ridge reported, "We were able to go below 35 pascals because the SIPs were so airtight."

At 50 pascals of negative pressure, the stick built room leaked 121 cubic feet of air per minute (CFM), while the SIP room leaked only 8 CFM.

In Comparison of R-value

Wood and R-19 fiberglass batt requires a full 6 3/4" area to achieve its advertised heat resistance value.

2" x 6" wood framing is actually 5 1/2" deep (not the required 6 3/4" depth). The resulting compaction equates to a 19% loss of R-value, or a degradation of 3.61

The direct thermal link of the framing lumber (conduction) results in a 28% loss of R-value, or another degradation of 5.32.

The loss of heat resistance due to aging (at only five years) is 18%, or further degradation of 3.42.

If all other related factors are perfect :

• No over compaction of batts at electrical boxes or wires, at plumbing, blocking, bracing, etc.
• The installation of the batts was exact
• The craft backing is contiguous with the drywall
• No damage done by follow-on trades resulting in voids which create convective loops.
• The vapor barrier was installed exactly as specified by the manufacturer.

The MAXIMUM resulting R-value is only 6.65

The ENTEK system walls are largely immune to the above deficiencies:

• Solid EPS foam has no convective voids.
• The splined panel keyways prevent air leakage.
• The EPS R-value does not degrade over time.
• The EPS Foam itself creates a nearly impervious vapor barrier.
• Deficiencies caused during installation of mechanical components can be easily corrected by applying spray polyurethane foam.

While whole wall values are difficult to precisely quantify; (because of the number, size and nature of openings.) The performance of the ENTEK system is far superior to conventional construction in all other respects.