Overview
ISO 20492-1:2008 - "Glass in buildings - Insulating glass - Part 1: Durability of edge seals by climate tests" specifies laboratory climate test methods to assess the durability of edge seals in pre-assembled, permanently sealed insulating glass units (IGUs). The standard defines two approaches tailored to different markets: Approach 1 (e.g., North America) and Approach 2 (e.g., Europe). It applies to IGUs with one or two airspaces and to units with intentionally open capillary tubes to equalize pressure, but it excludes IGUs with spandrel coatings and IGUs intended solely for decorative use.
Key topics and technical requirements
- Two testing approaches
- Approach 1 (frost/dew point): Measures final frost/dew point after pre-conditioning, weather cycling (temperature, humidity, UV) and final conditioning. Final frost/dew point of each airspace must be −40 °C or colder when measured per ASTM E546 or equivalent.
- Approach 2 (moisture-penetration index): Uses a moisture-penetration index (I). The average I across five specimens must not exceed 0.20; the worst specimen must not exceed 0.25.
- Test specimen requirements
- Typical specimen size: (355 ± 6) mm × (505 ± 6) mm.
- Double- and triple-glazed configurations with specified glass and airspace thicknesses (examples provided for double- and triple-glazed specimens).
- Marking: manufacturer ID, fabrication date, intended orientation for field installation.
- Vertical storage and support during testing; spare specimens recommended for breakage.
- Test method elements
- High-humidity conditioning, weather-cycling chambers, frost/dew point measurement, and methods for moisture measurement (including desiccant evaluation and Karl Fischer/950 °C drying methods in normative annexes).
- Limitations
- Not intended for IGUs exposed to long-term immersion or for some coated/absorptive products that can exceed sealant temperature limits.
Practical applications and users
- Intended users:
- Insulating glass (IGU) manufacturers for product qualification and quality control.
- Independent testing laboratories performing climate durability tests.
- Façade engineers, architects, specifiers, and building authorities evaluating IGU performance, energy retention and safety.
- Quality assurance and compliance teams preparing CE marking or market-specific regulatory documentation.
- Typical applications:
- IGUs used in windows, doors, curtain walls, skylights, roofs and internal partitions where edge-seal longevity affects thermal performance, vision, acoustic performance and mechanical safety.
Related standards
- ISO 20492 (other parts): Part 2 (chemical fogging), Part 3 (gas concentration & leakage), Part 4 (physical attributes of edge seals).
- Normative references cited: ISO 760 (Karl Fischer), EN 1279-1, ASTM E546, ASTM C1036, EN 572 series, etc.
Keywords: ISO 20492-1:2008, insulating glass, IGU edge seals, climate tests, frost/dew point, moisture-penetration index, durability testing, façade glazing compliance.