R-value vs. Time HFMA results of five insulation materials exposed to accelerated testing at 150 °F (66 °C) at 90% RH for up to 35 days.

R-value vs. Time HFMA results of five insulation materials exposed to accelerated testing at 150 °F (66 °C) at 90% RH for up to 35 days.

The U.S. Army Engineer Research and Development Center’s Construction Engineering Research Laboratory recently released new and innovative research investigating the long-term degradation of insulating materials based on short-term laboratory testing.

“Advanced insulation materials provide resistance to heat flow. Properly insulating shelters can reduce heating and cooling costs, as well as improve comfort. However, the long-term performance of insulation materials is relatively unknown. This research investigated the long-term performance of five commercially available insulation materials including nonwoven insulation liner, aerogel blankets, closed cell spray polyurethane foam (ccSPF), extruded polysterene (XPS), and fiberglass batt. Accelerated aging simulation experiments were conducted in an environmental chamber. All materials were subjected to 5 weeks in the chamber and exposed to various temperature and humidity conditions. Thermal conductivity using a heat flow meter apparatus (HFMA) and corresponding Rvalues of each material were calculated. The results indicate that moisture absorption was a major contributor to changes in the thermal properties of the materials. Additional degradation in R-values in ccSPF was caused by loss of blowing agent over time. The results of this research are expected to help formulate an accelerated aging methodology that allows reliable prediction of long-term advanced insulation materials performance.”

Of the four types of insulation evaluated, fiberglass and extruded polystyrene were only slightly affected by aging, retaining over 97% of their initial R-values, while the aerogels and closed cell polyurethane degraded by 15% and 27.5%, respectively. Even though they lost significant R-value, the aerogels still had the highest R-value after aging under high humidity conditions at elevated temperatures. These results indicate that the reduction in R-values over time for closed cell polyurethanes and aerogel blankets follows an exponential decay law.

Download the final report:

L. D. Stephenson, Andrew Heffron, Brenda B. Mehnert, Jedediah B. Alvery, Veera Boddu, Elizabeth J. Gao, Debbie J. Lawrence, and Ashok Kumar, Prediction of Long Term Degradation of Insulating Materials, ERDC/CERL TR-15-8, Construction Engineering Research Laboratory (CERL), U.S. Army Engineer Research and Development Center 2902 Newmark Dr., Champaign, IL 61822-1076 (May 2015).

National Center for Preservation Technology and Training
645 University Parkway
Natchitoches, LA 71457

Email: ncptt[at]
Phone: (318) 356-7444
Fax: (318) 356-9119