ASTM G197-08(2012)由美國材料與試驗協會 US-ASTM 發布于 2008。
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5. Significance and UseTop Bottom
5.1 This standard does not purport to address the mean spectral irradiance incident on tilted or vertical fenestration or building-integrated systems over a day, a season, or a year. The spectral irradiance distributions have been chosen to represent a reasonable near-upper limit for solar radiation when these systems are exposed to clear-sky conditions similar to those used to calculate solar heat loads of buildings. The diffuse spectral irradiance distributions can also be used to represent conditions when these systems are shaded from the direct sun.
5.2 Absorptance, reflectance, and transmittance of solar radiation are important factors in studies of light transmission through semi-transparent plates. These properties are normally functions of wavelength, which require that the spectral distribution of the solar flux be known before the solar-weighted property can be calculated.
5.3 To compare the relative performance of competitive products by computerized simulations, or to compare the performance of products subjected to experimental tests in laboratory conditions, a reference standard solar spectral distribution for both direct and diffuse irradiance is desirable.
5.4 The table provides appropriate standard spectral irradiance distributions for determining the relative optical performance of semi-transparent materials and other systems. The table may be used to evaluate components and materials for the purpose of solar simulation where the direct and the diffuse spectral solar irradiances are needed separately.
FIG. 1 Plot of Direct Spectral Irradiance on 20?? Tilted Sun-Facing Surface (Dotted Line) and 90?? Tilted Sun-Facing Surface (Solid Line) Computed Using SMARTS Version 2.9.2 Model with Input File in Tables 1 and 2 FIG. 2 Plot of Diffuse Spectral Irradiance on 20?? Tilted Sun-Facing Surface (Dotted Line) and 90?? Tilted Sun-Facing Surface (Solid Line) Computed Using SMARTS Version 2.9.2 Model with Input File in Tables 1 and 2A:污染程度是指窗玻璃的污染折減系數,污染折減系數主要是指,按照6個月清洗一次窗戶估計,該地區該房間實際窗玻璃的透射比與為污染玻璃透射比的比值。與窗戶所在房間類型和玻璃安裝的角度(水平、傾斜、垂直),一般情況下水平玻璃污染最嚴重,傾斜次之,但在南方多雨地區(長江以南),水平天窗的污染折減系數可以按傾斜天窗的數值選取。Q:采光計算里的窗地面積比怎么計算?...
光合作用測量系統的光源一般由LED組成,這種人工光源會安裝在葉室頂部,光照入射時可認為其方向與葉片表面垂直。而在自然條件下,植物葉片接受的光照既有直射,也有各個角度的散射。大氣中的氣溶膠態污染物或云會將太陽光“打散”,這直接改變了光照的入射角度。即便是在晴朗的天氣條件下,散射光的比例也能達到15%,在正午時甚至能達到30%-40%。...
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