ISO 20492-1:2008 establishes two methods for testing the durability of edge seals of insulating glass units by means of climate tests. The two methods are designated as approach 1 for markets such as North America and approach 2 for markets such as Europe. ISO 20492-1:2008 is applicable to pre-assembled, permanently sealed, insulating glass units with one or two airspaces, and with capillary tubes that are intentionally left open to equalize pressure inside the unit with the surrounding atmosphere. ISO 20492-1:2008 is not applicable to sealed, insulating glass units that contain a spandrel glass coating. ISO 20492-1:2008 does not apply to insulating glass units whose function is decorative only.