For facade applications a lifetime of about 20 years is expected. Observations and measurements have shown that some performance parameters can deteriorate over time by the influence of weathering factors. Important stress factors for electro-active dynamic windows are solar radiation (especially the UV part), high temperature because of heating, thermal shock (day/night), high humidity, shock rain, and last but not least electrochemical stress due to switching. Because it is impractical to wait for results from real time testing, durability of electro-active switchable windows is tested by accelerated aging tests. The electrical switching behavior of EC samples can be described with current - time relationships. Any aging effects or degradations result in a change of electrical switching characteristic quite earlier than they are visible with human eye.
The test procedures covered in the PM&VL4 include:
- rapid but realistic cycling between high and low light transmission states.
- environmental parameters that are typically used in weatherability tests such as simulated solar exposure and high temperature, which are realistic for the intended use of electro-active glazings.