改裝現有的室外照明 Modifying the Existing Lightings

香港有部分室外照明(例如街燈、大廈室外燈光裝飾等)的設計並不對減少光害有利。以街燈為例,它們的主要作用是照亮地面,提供保安和引路等作用。可惜由於街燈燈罩設計不良,令部分光線會向上照耀。向上照耀的光線沒有實質作用,只有浪費和增加光害。

Some of the outdoor lightings in Kong Hong, for example street lamps and lighting decorations on buildings' walls, have poor designs in term of dark-sky friendly. For street lamps, their main purpose is for security and guiding by illuminating the road. However their lampshades are poorly designed so that a portion of light energy is scattering up instead of down. Upward lighting is useless and wasteful, and also causes light pollution.

優良的燈罩設計,例如「截光型燈具」將光線聚焦在向下0至65度範圍內,盡量消除向天照耀的光線、
減少光害。

The better design of lampshades, like the so-called "Full-Cut-Off Lighting" or "Down Lighting", should focus the light energy to 0 to 65 degrees downward, meaning that minimum light is pointing upward and hence reduce light pollution.


左:截光型燈具的設計;右:非截光型燈具的設計

Left: The design of Full-Cut-Off Lighting;Right: The design of non-Full-Cut-Off Lighting.

香港大部分街燈的燈具設計沒有阻攔光線向天照耀:從圖中所見,街燈上面的樹葉都被照光了;

Most of the street lamps in Hong Kong hadn't blocked the light shining upward: from the picture we know that the tree above the lamp is illumined

但香港有少部分的街燈,具備截光型燈具的特性:留意圖中箭頭的位置,明顯見到截光型燈具發揮作用,減少光射向上方照耀。

Part of the street lamps in Hong Kong equipped with the properties of full-cut-off: pointed lamps show how the full-cut-off reduced the upward shine.