Spectral effects on the transmittance, solar heat gain, and performance rating of glazing systems
Spectral effects on the transmittance, solar heat gain, and performance rating of glazing systems
复制标题
DOI：
10.1016/j.solener.2008.12.012
复制
发表时间：
2009-06
期刊：
影响因子：
6.7
通讯作者：
C. Gueymard;W. Dupont
中科院分区：
文献类型：
--
作者：
C. Gueymard;W. Dupont
这项研究调查了垂直或倾斜玻璃系统的太阳热增益系数(SHGC)和可见光透过率(VT)额定值的潜在变化，这些变化可能会导致用作光谱加权函数(SWF)的参考光谱的变化。这种SWF是根据它们的光谱值来评估宽带平均光学性质，并获得所需的整体性质的评级所必需的。欧洲和北美评级机构目前为SHGC和VT指定的主权财富基金现在已经过时，并讨论了它们的不足之处。描述了ASTM最近采用的6种潜在替代方法，包括3种直接辐照度光谱和3种入射到不同倾角(20°、37°和90°)倾斜表面上的全局辐照度光谱。其中一些光谱是为建筑能源应用量身定做的，包括建筑集成光伏(BIPV)。利用37个玻璃系统试件的典型数据集，讨论了倾斜度对屋顶天窗用玻璃系统U系数和SHGC的影响。该数据集还获得了当前北美SWF变化对SHGC的光谱影响，并显示出与当前额定值的小到中等偏差(窗的−为2%至+7%，天窗的−为3%至+11%)。对于大多数玻璃系统，VT的变化在±2%以内。要消除当前用于SHGC和VT的SWF中的不一致，建议对这两个属性使用单个SWF。为了提高准确度和对现行标准的依赖，还建议SHGC和VT的SWF为最近两个ASTM G197-08全球辐照度光谱之一，具体取决于应用(入射到垂直表面的入射用于窗户应用，入射到20°倾斜表面的入射用于天窗应用)。但是，建议不要更改色度计算(基于D65光源)。
This study investigates the potential changes in Solar Heat Gain Coefficient (SHGC) and Visible Transmittance (VT) ratings of vertical or tilted glazing systems that would result from a deliberate change in the reference spectrum used as Spectral Weighting Function (SWF). This SWF is necessary to evaluate broadband-average optical properties from their spectral values, and obtain the desired rating of such bulk properties. The SWFs currently specified by rating institutions in Europe and North America for SHGC and VT are now outdated, and their inadequacies are discussed. Six potential replacements, which have been recently adopted by ASTM are described, including three direct irradiance spectra and three global irradiance spectrum incident on tilted surfaces of various tilts (20°, 37° and 90°). Some of these spectra have been tailored for use in building energy applications, including Building-Integrated Photovoltaics (BIPV). The effect of tilt on the U-factor and hence SHGC of glazing systems used for skylights on roofs is discussed, using a representative dataset of 37 glazing system specimens. The spectral effects on SHGC induced by a change in the current North American SWF are also obtained for this dataset, and show small to moderate deviations from current ratings (−2% to +7% for windows, and −3% to +11% for skylights). The variations in VT are within ±2% for most glazing systems. To remove the current inconsistency in the SWFs used for SHGC and VT, it is recommended that a single SWF be used for both properties. For improved accuracy and reliance on active standards, it is also recommended that the SWF for SHGC and VT be either one of the two recent ASTM G197-08 global irradiance spectra, depending on application (incidence on a vertical surface for window applications, and incidence on a 20°-tilted surface for skylight applications). No change in colorimetric calculations (based on the D65 illuminant) is recommended, however.