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Introduction | Details of Test Section Construction
Instrumentation and Test Procedures |
Test Results | Conclusion
Test Results
The air temperatures of 50°F imposed in the climate chamber and 100°F imposed in the metering chamber yielded a mean insulation temperature of about 75°F and a temperature difference of 45°F to 48°F from the bottom to the top of the insulation.
Depending upon the configuration, 125 Btu/h to 270 Btu/h flowed upwards through the test sections.
The severe thermal bridges present in the “over the purlin” configuration are evident not only in the large heat losses, low R-values and high U-values, but also in the relatively higher temperatures of the top surface over insulation, the top surface over purlins, and the bottom surface under purlins compared to these temperatures for the Simple Saver configuration. The Simple Saver configuration had the bottom surface of the liner at the level of the bottom of the purlins. The “over the purlin” configuration had the bottom surface of the liner closer to the top of the purlins. Therefore, the temperatures of the bottom surface under insulation for the “over the purlin” configuration are slightly cooler than for the Simple Saver configuration.
At the conclusion of each test, before the test section was moved out of the LSCS, holes were drilled through the roof panels to admit a pin probe. It was used to determine depth from the bottom of the roof panels to the top of the liner or purlins. Eight holes were drilled parallel to the purlins at each location shown in Fig. 4. Each set was two holes in flat parts of each of the four roof panels within the vertical projection of the metered area. The numbers in Fig. 4 are the average of the eight measurements at each location for the fiberglass insulated Simple Saver configuration. The results are added to Fig. 4. It is assumed that the entire cavity was filled by the fiberglass insulation since it was free to expand.
Figure 5 shows the depth from the bottom of the roof panels to the top of the liner for the “over the purlin” configuration. Again, eight holes were drilled parallel to the purlins at each location shown in Fig. 5, with two of each set in flat parts of each of the four roof panels in the metered area. The numbers in Fig. 5 are the average of the eight measurements at each location for this configuration with fiberglass insulation. Unlike in the fiberglass-insulated Simple Saver configuration, the insulation is severely compressed between the roof panels and the liner. The average gap from the roof to the purlins is 1.43 in. for the R-30 Simple Saver and 1.66 in. for the R-19 fiberglass draped over the purlins. The Simple Saver with fiberglass has an R-11 blanket between the clips and purlins. The draped R-19 fiberglass is between the clips and purlins. Therefore, the average gaps of 1.43 in. and 1.66 in., respectively, are also reasonable.
