OUTDOOR MEASUREMENT OF THE TOTAL SOLAR ENERGY TRANSMITTANCE AS A FUNCTION OF THE ANGLE OF INCIDENCE

摘要

An apparatus is described which enables the Total Solar Energy Transmittance (g-value) to bemeasured at any angle of incidence using the sun as the source of radiation. The glazing or shadingdevice to be investigated is placed in front of a cooled absorber plate in which heat flux sensors areembedded. This assembly is mounted onto a tracking device. By tracking the sun it is possible toconstantly maintain any desired angle of incidence with respect to the sample surface.To determine the g-value the optical properties of the sample have to be known. The solarirradiation consists of a direct and a diffuse component. Therefore the results are corrected opticallyand thermally to yield the direct component of the g-value at reference conditions. To do this, eachsample glazing investigated will also be measured in a north-facing position with solely diffusehemispherical insolation. From investigating several glazing systems we conclude that the apparatusdescribed and its evaluation procedures provide a reliable way to measure the angular dependent gvalueof even complex glazings.