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Hotbox Test R-value Database

Agriboard Wall Systems



During January 1998, the steady-state thermal performance of the Agriboard wall system was measured in the ORNL BTC Rotatable Guarded Hot Box using ASTM C-236 experimental procedure. Steady air temperatures (90 deg.F on one side and 50 deg.F on the other) and air velocities were set on both surfaces of the tested wall during the test.

Description Of Wall

The Agriboard wall system is based on the structural insulating panel technology. During the test double-core Agriboard panels (7-7/8-in. thick) were used. They consisted of two 3.5-in. thick core panels made of compressed straw and two OSB skins. Agriboard panels were joined using laminated OSB profiles. During the Hot box testing, the Agriboard wall was not covered by any finish materials.

Thermal conductivity of Agriboard core insulation was measured at the ORNL BTC Laboratory using ASTM C518 method.  Density of Agriboard core material was about 14.0 lb/ft3 [224.0 kg/m3].  Thermal conductivities for the Agriboard Straw panel are presented in the table below for different mean temperatures.

Thermal conductivities of straw-core panels tested in the hot-plate apparatus using ASTM C518 procedure.


Sample thickness

in. [m]

Test mean
Temperature F [C]

Conductivity k a

Btu-in./hft 2F [W/mK]

Agriboard straw-core panel #1


39.90 [4.39]

0.52 [0.07493]

Agriboard straw-core panel #1


75.04 [23.91]

0.57 [0.08183]

Agriboard straw-core panel #1


109.98 [43.32]

0.65 [0.09296]

Agriboard straw-core panel #2


39.88 [4.38]

0.49 [0.07071]

Agriboard straw-core panel #2


75.00 [23.89]

0.54 [0.07836]

Agriboard straw-core panel #2


109.94 [43.30]

0.62 [0.08976]



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