Sensitivity of fenestration solar gain to source spectrum and angle of incidence
- Florida Solar Energy Center, Cocoa, FL (United States)
The solar heat gain coefficient (SHGC) is the fraction of solar radiant flux incident on a fenestration system entering a building as heat gain. In general it depends on both the angle of incidence and the spectral distribution of the incident solar radiation. In attempts to improve energy performance and user acceptance of high-performance glazing systems, manufacturers are producing glazing systems with increasing spectral selectivity. This poses potential difficulties for calculations of solar heat gain through windows based upon the use of a single solar spectral weighting function. The sensitivity of modern high-performance glazing systems to both the angle of incidence and the shape of the incident solar spectrum is examined using a glazing performance simulation program. It is found that as the spectral selectivity of the glazing system increases, the SHGC can vary as the incident spectral distribution varies. The variations can be as great as 50% when using several different representative direct-beam spectra. These include spectra having low and high air masses and a standard spectrum having an air mass of 1.5. The variations can be even greater if clear blue diffuse skylight is considered. It is recommended that the current broad-band shading coefficient method of calculating solar gain be replaced by one that is spectral based.
- OSTI ID:
- 433717
- Report Number(s):
- CONF-960606-; TRN: IM9709%%150
- Resource Relation:
- Conference: 1996 annual meeting of the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE), Inc., San Antonio, TX (United States), 22-26 Jun 1996; Other Information: PBD: 1996; Related Information: Is Part Of ASHRAE transactions 1996: Volume 102, Part 2; PB: 836 p.
- Country of Publication:
- United States
- Language:
- English
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