In high school, I remember watching the track team race around the track. One runner Peter, a farm kid, was fascinating to watch as he always grabbed the early lead. Peter always looked so fast but in the end he would typically finish in 3rd or 4th place. In that moment, early in the race, Peter looked like a world class athlete that would easily win gold at the Olympics. In those early moments, that frozen time, the measure of performance was perfect.
Thirty-six years later and I see the same thing happening in the rigid insulation market. Its like watching Polyiso, and XPS insulation running just like Peter, getting off to a tremendous lead regarding R-value, but then fading out at the end. That perfect moment in time is when that R-value gets measured and they look like superheroes but in reality they just “blowhards.” Pardon the pun as the blowing agent escapes and lowers the r-value. (LEARN WHY)
When it comes to below grade or roofing insulation, Polyiso and XPS start out with really good R-value numbers but they don’t last (LEARN MORE). Unfortunately, you pay for these early performance numbers, sometimes as much as 50% more. Paying for performance isn’t bad but not knowing that the product will fade out is a different matter.
The old idiom, “slow and steady wins the race” really holds true in insulation. EPS might start out slow (or lower r-value) but is consistent through its life and ultimately wins the race. Not only does EPS (Expanded Polystyrene) have a steady consistent R-Value but when compared with XPS and Polyiso, it also performs better in the field. XPS and Polyiso, when wet, hold the moisture and loss much of its r-value. EPS has the ability to hold its r-value and even expel moisture under exsiccate conditions.
Next time, when you’re looking to specify or install insulation on a project, remember that Polyiso and XPS look great at the beginning but EPS is the steady performer and the best value in rigid insulation. Your customer deserves the winner - EPS.
Early this year, the National Roofers Contractors Association, made a recommendation to it's members that Polyisocyanurate Insulation revise "its design in-service R-value recommendation to 5.0 per inch thickness." This declaration was the second time Polyisocyanurate's R-value was downgraded in the last 2 years. For some of us "Energy Aficionados," who understand the principles of insulation off-gassing, determined it was time to re-examine LTTR testing (View Technical LTTR Bulletin).
LTTR really looks at Long-Term Thermal Performance of insulation as 5 years. Do we expect a building to last only five years? How is 5 years a true quantitative analysis of R-value performance?
We do not replace insulation in a building every 5 years, why would we think that is long-term? Most building in the U.S. are built to last 50 years, some 100 years. Long-term R-value should be figured at 50 years… right? We know off-gassing continues to happen after 5 years. Let's re-evaluate what we are doing as an industry and modify Long-Term Thermal Resistance to at least 50 years.
The real question maybe why? and why another change after last year’s change? The answer is independent testing. According to research conducted by BSC (Building Science Corporation) and others, “the thermal performance of some insulation materials changes as they age. The R-Value of Polyisocyanurate decreases as some of the gasses … diffuse out and are replaced by air.” This is known by several names - Thermal Drift, Gas Replacement Process or Off Gassing.
What the research has shown is that unlike EPS (Expanded Polystyrene) Insulation that increases its R-Value when the temperature decreases, ISO Insulation R-Value actually goes down. Bottom line: In the north, when you need the r-value the most, its not there like we thought.
• If you need to use ISO - the BCS Recommendation is to use it in a “hybrid insulation approach” with a cold stable R-Value insulation like EPS.
• Try to substitute out ISO Insulation and use EPS or the New Neopor Plus Insulation.