合宜的自然光照明和良好的照明系統設計，可減少建築物照明用電需求，有助於節約能源；此外自然光照明的環境，對於健康、情緒，學習效能和工作效率皆具有正面影響。稜鏡具有改變光行進軌跡之特性，使用稜鏡結構於自然光照明系統中，可達到利用稜鏡引導日光與增加收集效率的功用；將稜鏡結構架設於建築物的屋頂或外牆上，使之位於日照側，收集和引導日光，可作為自然光照明系統的集光元件，兼具減少眩光產生和增加自然光照明效率，並達到節約能源的功能。光路計算與精確的集光能量分布，可提高導光的精確性與集光效率，有助於自然光照明系統設計。
日光照射稜鏡型集光器表面，穿透光經過反射與折射過程，主要射出光的特性與組成集光器之直角稜鏡單元的頂角有關，且隨日照角度而有所不同。本文在幾何光學原理基礎上，建立一套簡易的矩陣光學追跡模式，利用此模式，可精確計算不同角度入射直角稜鏡的平行光束，穿透稜鏡之後的射出光強度分布。應用此模式與邊緣光線原理可精確計算白天時，直接照射集光器的陽光，經稜鏡架構穿透的主要射出光強度、行進方向特性。對日照於45°頂角的稜鏡型集光器計算，得出上午與下午時段直接日照條件下的稜鏡射出光，以直接朝向稜鏡架構以外之空間射出為主，可直接導引作為照明應用，而接近正午時分之射出光，則主要射向相鄰的稜鏡單元。本文亦對日照於不同頂角的直角稜鏡型集光器，進行詳細的射出光特性計算，發現日光照射稜鏡型集光器表面時，射出光主要由稜鏡單元的斜面射出，且其分布狀態隨稜鏡頂角而有所不同。而使用的稜鏡單元頂角增加，則直接朝向稜鏡架構以外之空間射出，可直接導引作為照明應用的整體射出光強度水平將降低。直接日照稜鏡型集光器的主要射出光由稜鏡單元斜面射出，利用此特性，可作為作為提高自然光照明系統效能與系統設計過程之參考。分析由斜面射出光的分布情形，得到組成稜鏡集光器的稜鏡單元數大於10的情況下，斜面射出光中，直接朝向稜鏡架構以外空間射出的射出光所佔比例趨於穩定，因相同集光面積下，使用之材料隨稜鏡單元數增多而減少，可以用較少的材料實現穩定的日光收集，更為經濟與環保。本文提出了一種可提高太陽能利用效率的自然光照明系統的模型。這個模型是由一個稜鏡型的日光集光器，重新導引日光進入室內的反射面和進行室內照明的漫反射面組成。稜鏡型的日光集光器和遮陽架構除了可降低眩光造成的不適外，同時作為自然光照明系統的集光元件。

In buildings, efficient lighting systems and excellent design of interior natural light illumination can contribute to energy savings; meanwhile, natural light illumination systems have the potential to improve human health, mood, performance and productivity. Prismatic elements are widely used in natural light illumination systems for redirecting and collect daylight. Prismatic elements can be part of a daylight illuminate system located on the roof or façade of buildings and can be used as collectors to collect and guide daylight to reduce glare and save energy. An analysis of the distribution of the energy and ray-tracing can improve the performance of daylight guiding systems and aid in the design of natural light illumination systems. The characteristics of the light that emerges from the surface of a right-angled prism vary with the apex of the prism and the incident angle of the sunshine illuminating the surface of the prismatic daylight collector. Based on the principles of optics, this article presents a simple mathematical three dimensional matrix ray-tracing methodology through which a detailed intensity distribution of parallel light beam incident onto a right angled prism from different incident angles can be calculated precisely. The direction, concentration and distribution of intensity of the emerged light from the parallel light incident onto a surface of the right-angle prism, as well as daylight illuminate on a prismatic collector are precisely calculated. The detailed calculation of the emerged light re-incident onto the adjacent prism or emerged out of the right angled prismatic element with a 45° apex angle presented that most of daylight are directly emerged out and are confined in some directions at earlier morning and afternoon; the emerged light re-incident into the adjacent prism at noon around. This paper also investigates the effect of the apex angle of a right-angled prismatic collector on the performance of the collector using this matrix ray tracing model and the edge principle. It was found that the majority of the light emerges from the hypotenuse of the right-angled prism when sunshine is incident on the surface of the prismatic daylight collector; furthermore, the distribution of the light can be shifted by changing the apex of the right-angled prismatic collector. The direct illumination level of the light emerging from the hypotenuse decreases as the apex of the right-angled prism is increased. The intensity distribution of the majority of the light emerging from the hypotenuse of a right-angled prism can be used to guide the design of natural light illumination systems and enhance their performance. The percentage of light emerging from the hypotenuse decreases with the number of prismatic elements because the relative area of the emerging light that reaches the adjacent prism increases with the number of prismatic elements. The analysis of the relative area of the emerging light that reaches the adjacent prism according to the edge ray principle shows that the total area is constant when the number of prismatic elements is greater than 10; an economical prismatic daylight collector can be realized with less material due to the larger number of smaller prisms with the same apex. This detailed calculation model of parallel light beam incident to a prismatic element can be applied to the hybrid natural light illumination system as well as to the prism-relative solar illumination system for the improvement of efficiency. This paper proposes a model of a natural light illumination system that would improve the efficiency of solar energy use. This model is composed of a prismatic daylight collector, a reflector for re-directing daylight into the room and a diffuse reflector for indoor illumination. The prismatic daylight collector and the daylight canopy not only decrease the discomfort of glare but also collect daylight for the natural lighting system.

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