How to Measure the U-Value: Temperature Based Method vs. Heat Flux Based Method
In a study performed by students at East Bavarian Technical University, the measurement quality of U-values measured with a Temperature Based Method (TBM) versus a Heat Flux Based Method (HFBM) were compared. It was found that the HFBM U-value measurement not only stabilised more quickly, but was also more accurate.
By measuring the U-value of a refrigerator’s insulation wall, it was found that TBM-derived U-value varied with day and night temperature cycles across 41 hours, while the U-value obtained with the U-value Kit stabilised after 12 hours. The report explains the underlying reason for the difference between the two results: A constant convective transfer coefficient is assumed for the TBM, while this coefficient is measured in the HFBM.
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