This International Standard specifies the test method for passenger car (ISO3833:1977, 3.1.1) windscreen defrosting and demisting systems, when these are fitted.
This International Standard does not specify reference areas or levels of performance.
The test condition of −18°C±3°C specified for defrosting systems will meet the majority of cold climatic requirements.
The tests for demisting systems are conducted at a temperature of −3°C±1°C, since this is the practical minimum temperature at which mist, as defined in 3.7, can normally occur.