The useful life of IGUs with an absorptive ECC may depend on their ability to maintain an acceptable uniformity when used in an IGU for buildings applications. As described in Section 1.2^{2 ,4} (See Appendix X1, Sections X1.4 and X1.5), this test method is intended to provide a means for measuring the uniformity of an absorptive electrochromic coating (ECC) on a glazing surface, which will ultimately be one of two or more of the glazings in a preassembled permanently sealed insulating glass unit (IGU).

Effects of Test Procedures—Data generated using this test method may be used to evaluate and compare the effects of subjecting ECCs in IGUs to the accelerated weathering procedures described in Test Methods E 2141, E 2240, or E 2241 and Practice E 2094. This test method requires the measurement of uniformity as a basis for evaluating changes in one of several performance parameters.

4.2.1 Changes in the uniformity of the test specimens may vary from none to significant. Some physical changes in the specimens may be visible when there are no apparent changes in the performance. Similarly, performance changes may occur with no visible changes in the specimens.

4.2.2 All conditions of measurement in this test method must be described in the report so that an assessment of their significance can be made.

Sequencing—If this test method is performed as part of a combined sequence with other measurements of the ECC perfomance (see 8.2) and visual inspection (see 8.3 in Test Methods E 2141, E 2240, or E 2241) determined at the end of one of the test methods, the result may be used as the initial uniformity measurement for the next test; duplication of these uniformity measurements is not necessary unless so specified.

1.1 The test described is a method for measuring the uniformity of an absorptive electrochromic coating (ECC) in a static colored or bleached state on a glazing surface, which will ultimately be one of two or more glazings in a preassembled permanently sealed insulating glass unit (IGU). Cross sections of typical electrochromic windows (ECWs) have three to five-layers of coatings that include one to three active layers sandwiched between two transparent conducting electrodes (TCEs, see Section ). Examples of the cross-sectional arrangements can be found in "Evaluation Criteria and Test Methods for Electrochromic Windows." (For a list of acronyms used in this Standard, see , Section ).

1.2 The test method is applicable only for layered (one or more active coatings between the TCEs) absorptive ECCs on vision glass (superstrate and substrate) areas planned for use in IGUs for buildings, such as glass doors, windows, skylights, and exterior wall systems. The layers used for electrochromically changing the optical properties may be inorganic or organic materials between the superstrate and substrate and may include laminates.

1.3 The ECCs used in this test method will ultimately be exposed (Test Method E 2141) to solar radiation and deployed to control the amount of radiation by absorption and reflection and thus, limit the solar heat gain and amount of solar radiation that is transmitted into the building.

1.4 The test method is not applicable to other types of coatings on vision glass with other chromogenic coatings that cannot be held in a static colored or bleached state.

1.5 The test method is not applicable to IGUs that will be constructed from superstrate or substrate materials other than glass.

1.6 The test method is not applicable for measuring the uniformity of ECC coatings during the coloring or bleaching processes.

1.7 The test method referenced herein is a laboratory test conducted under specified conditions. This test method is intended for use in assessing the changes in uniformity of an ECC on vision glass, which will be incorporated into an IGU and subjected to a series of tests for assessing the durability of the coating or the IGU unit, or both.

1.8 The values stated in metric (SI) units are to be regarded as the standard.

1.9 There is no comparable International Standards Organization Standard.

1.9 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory requirements prior to use.