This paper presents and analyzes the experimental results from a full-wall (guarded hot box) thermal testingstudy performed by Architectural Testing, Inc., of York, PA. The tests were performed on 8 ft. x 8 ft. wood frame wallsinsulated with three types of cavity insulations: fiber glass batts, open-cell spray polyurethane foam (ocSPF) andclosed-cell spray polyurethane foam (ccSPF). In addition, thermal performance of a combination of ccSPF andpolyisocyanurate insulated sheathing is also measured. This full-scale test method goes beyond simple thermalconductivity testing of insulation materials and includes real-world effects of air infiltration and meantemperature. Specifically, it includes the effect of air infiltration by simulating a 15 mph wind applied to the outsidesurface of the test walls. In addition, the effect of mean test temperature on wall thermal performance is measuredusing outdoor temperatures of -15oF, 25oF and 115oF. A Wall Performance Index (WPI) is determined for thedifferent walls tested, providing a rating of actual versus expected thermal performance. Results show WPI isdependent upon mean temperature and air infiltration. The WPI for fiber glass insulated walls are significantlyreduced by wind loading and changes in the mean test temperature. Walls made from open-cell foam show consistentWPI values that are lower than expected, but relatively unaffected by wind load and external temperature. Closed-cellspray foam shows WPIs that are consistently at or above expected values, regardless of mean temperature and airinfiltration. Reasons for these observed effects are discussed.
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