1.1 This International Standard specifies methods for the instrumental measurement of irradiance on a planar surface. This includes not only natural solar radiation but also intensified natural solar radiation and radiation produced by laboratory light sources. 1.2 For measurement of solar radiation for natural weathering and accelerated natural weathering, instrumental techniques include the continuous measurement of total solar, solar ultraviolet and spectral solar (ultraviolet) irradiance and the accumulation, or integration, of instantaneous data to provide the radiant exposure. 1.3 For measurement of radiation in artificial accelerated weathering or artificial accelerated irradiation exposures, instrumental techniques include the continuous measurement of total or defined wavelength bands of ultraviolet radiation, visible spectral irradiance and/or ultraviolet spectral irradiance and the accumulation, or integration, of instantaneous data to provide the radiant exposure. 1.4 This International Standard does not specify procedures using blue-wool standards, chemical actinometry or polymeric or other film dosimetry.