STP1200

    Fraction of the Global Normal Irradiance Incident from the Northern Part of a Clear Sky

    Published: Jan 1992


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    Abstract

    The luminous flux received from a clear blue sky at the north side of a building was determined relative to the global normal illuminance with a commercial photometer using a hemispherical diffusor. Measurements with narrow band interference filters were also made to obtain information on the ratio of these quantities in the violet and blue parts of the visible spectrum. It was found that the blue sky provides 6.3% of direct sunlight at a wavelength of 370 nm. In comparison, a value of 4.7% was found for the luminous flux (not spectrally resolved).

    It is concluded that materials which degrade principally by absorption of UV light will last approximately 15 times longer on the north side of a building than when fully deployed on a southern exposure.

    Keywords:

    Sunlight, blue sky radiation, UV absorption, sealant degradation, Northern and Southern exposure


    Author Information:

    Pernisz, UC
    Senior Research SpecialistScientist, Sealants department of the Dow Corning Corporation, Midland, MI

    Klosowski, JM
    Senior Research SpecialistScientist, Sealants department of the Dow Corning Corporation, Midland, MI


    Paper ID: STP14893S

    Committee/Subcommittee: C24.40

    DOI: 10.1520/STP14893S


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