Ug-value and edge heat loss of triple glazed insulating glass units:A comparison between measured and declared values
Triple glazed low-e coated insulating glass units with argon filling of five different suppliers on the European market with a declared thermal transmittance in the undisturbed centre of glass (Ug-value) of 0.6 W/m2K have been purchased from resellers and tested in a guarded hot plate at vertical po...
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| Published in: | Journal of Building Engineering Vol. 44; p. 103031 |
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| Main Authors: | , , , , , |
| Format: | Journal Article |
| Language: | English |
| Published: |
Elsevier Ltd
01-12-2021
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| Subjects: | |
| Online Access: | Get full text |
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| Summary: | Triple glazed low-e coated insulating glass units with argon filling of five different suppliers on the European market with a declared thermal transmittance in the undisturbed centre of glass (Ug-value) of 0.6 W/m2K have been purchased from resellers and tested in a guarded hot plate at vertical position. The measured results showed deviations towards higher values for all 5 types. These have been analysed by recurring to the determination of the two main factors namely the gas mixture in the two cavities and the emissivity of the coated glass panes. Non-destructive measuring methods for gas mixture analysis and standardized calculation methods for the Ug-value have been used to analyse the influence of these two factors. In a further step the edge heat loss due to the spacer of the insulating glass units has been measured by using two “halves” of each glazing type with a double edge running through the middle of the measured sample. This was done following a standardized test method for the determination of the edge heat loss of Vacuum Insulation Panels (VIP). Finally, pieces of the coated glass panes were cut out of the glazing units and their emissivity measured with both an infrared spectrometer and an emissiometer. Results showed an increased emissivity value for the coated surfaces leading to higher Ug values than measured. This is partly due to the exposure to air and the possible degradation of the coating. The investigation shows non-destructive emissivity determination is needed to get more accurate in-situ emissivity values of the coatings.
•Comparison of measured and declared Ug-Value of low-e coated triple glazing units.•Measurement and calculation standards to be complementary not mutual replacing.•Difficulties for measuring the emissivity of coatings according to the relevant standard. |
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| ISSN: | 2352-7102 2352-7102 |
| DOI: | 10.1016/j.jobe.2021.103031 |