Closed-Cell Foam Excels in Whole-Wall Thermal Performance Testing

March 06, 2008 |

Whole-wall thermal performance testing conducted on behalf of the Spray Polyurethane Foam Alliance (SPFA) by Architectural Testing, Inc. shows that wall assemblies that include closed-cell polyurethane foam insulation deliver superior insulation performance.

For the tests, performed in accordance with ASTM C 1363-05 Standard Test Method for Thermal Performance of Building Materials and Envelope Assemblies by Means of a Hot Box Apparatus , a series of wall assemblies was constructed using various combinations of insulating materials and weather barriers. Each specimen was tested in a guarded hot box for thermal resistance performance, including the effects of air leakage. A pressure differential was maintained throughout all the tests to induce air leakage through the system and simulate real-world conditions.

The test specimens were built with 2 x 4 framing members 16-inch on-center, with no exterior weather barrier. The exterior sheathing was half-inch polyisocyanurate board and the interior sheathing was half-inch gypsum board. 1.5 inches of closed-cell polyurethane foam comprised the cavity insulation.

Test Results Summary -- Architectural Testing Inc. (09-01-06 valid through 08-06-10)

  Exterior Temperature

(Deg F)
Interior Temperature

(Deg F)

(in WC)
Overall Thermal Resistance Air Flow Heat Flow (BTU/hour
No Wind 25.03 70.00 0.026 15.695 0.00 188.210
15 mph wind 25.01 70.01 0.114 13.643 0.36 216.623
15 mph wind -14.99 70.00 0.125 12.384 0.53 450.753
15 mph wind 70.01 115.01 0.096 11.521 0.62 256.522

The concept of whole-wall thermal performance testing was developed by Oak Ridge National Laboratory (ORNL) in 1994, with the goal of a nationally-accepted procedure for estimating the whole opaque wall R-value (whole-wall R-value), independent of system type and construction materials. Whole-wall R-value includes the thermal performance of not only the clear-wall area, with insulation and structural elements, but also typical envelope interface details, including wall/wall (corners), wall /roof, wall/floor, wall/door, and wall/window connections. Results from these detailed computer simulations are combined into a single whole-wall R-value estimation and compared with simplified center-of-cavity and "clear wall" R-values.

How does closed-cell polyurethane foam's performance compare with traditional systems?

ORNL's website features whole-wall interactive calculators as part of its material database for whole-wall building energy calculations. The results for closed-cell polyurethane foam from the Architectural Testing Inc. study are consistent with those listed in the ORNL database.

By setting the ORNL interactive calculator to specific framing and structural parameters, then simply switching the cavity insulation material, visitors can compare different systems and assemblies. Results returned*:


  Whole-Wall R-Value Exterior Corners Wall/Slab on Grade Wall/Partition Wall Wall/Roof Window Header Window Sides Window Sill Door Header Door Sides
Closed-Cell Polyurethane Foam 15.1 12.31 11.1 17.1 14.23 8.78 8.08 8.21 7.79 8.05
Glass Fiber (R-11 batts) 11.59 9.44 9.02 12.61 11.89 7.93 7.48 7.44 6.96 7.31
Cellulose 12.32 10.09 9.44 13.44 12.4 8.12 7.48 7.61 7.21 7.48

Values for Wood Frame, 2 x 4 16 o.c., 0.5” Foam Sheathing, Wood Siding

For a direct link to the ORNL interactive whole-wall calculator, or to download a copy of the Architectural Testing Inc. report, visit

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