Backlight refers to light which is emitted "behind" the fixture (such as into the house side of a streetlight), often into areas which do not need illumination. In such installations, the light output needs to be directed "forward" from the pole. ![]() Many light fixtures are designed to be mounted above and to the side of an area of intended illumination (such as streetlights mounted on poles on the side of a roadway). Founded in 1894 as the American Society of Heating and Ventilating Engineers, ASHRAE is a non-profit trade organization with the mission statement "To advance the arts and sciences of heating, ventilating, air conditioning and refrigerating to serve humanity and promote a sustainable world", with the vision of becoming "the global leader, the foremost source of technical and educational information, and the primary provider of opportunity for professional growth in the arts and sciences of heating, ventilating, air conditioning and refrigerating" (source: Apparently perceiving a lack of leadership in lighting, ASHRAE has also started to issue its own standards and practices for illumination, too. ![]() The American Society of Heating, Refrigerating and Air Conditioning Engineers. In the latter instance, "architectural lighting" generally refers to illuminated architectural features other than windows where indoor illumination is escaping, but if interior illumination is being left turned on specifically to modify the exterior appearance of a building, it may be considered architectural lighting, too. Sometimes only including exterior lighting directed on to those areas, but in other cases also including internal illumination through translucent exterior surfaces. Illumination of buildings, facades, structures, or other architectural features. This effect is demonstrated on a city block where one streetlight is not functioning the space around that fixture won't be totally void of all light - generally, a notable amount of "ambient light" will be found to spread in from the brighter areas on the street. In other words, a city block may have many separate streetlights which each are brightly (directly) illuminating their immediate areas, but all together, the light they each generate ends up creating an ambient light level which suffuses throughout the area (and perhaps beyond). In artificial lighting engineering, the term is also sometimes used to describe indirect artificial light that is light which is being added, but which carries into parts of the area in question by reflection and other scattering, and by leakage from more distant luminaires, rather than shining right from a luminaire which is directly illuminating a particular spot. Originally generally used by photographers/cinematographers to describe the existing light in a scene (as opposed to light which they add). ![]() In any case, when we use any of these terms elsewhere on this website or in our other publications, the definitions below indicate our intended meanings. We have done our best to include the most proper and fitting definitions of the terms listed here, and in the cases where certain terms are commonly used (or misused) to mean multiple things, to explain our definition(s) of choice. On this page, we provide some definitions and explanations of some of this terminology. Some terms are commonly used when talking about lighting practice, but have different meanings to different people this is a frequent source of talking cross-purposes in our field. Some of the terminology used in lighting practice and analysis, and in studying the environmental effects of light, are not commonly used elsewhere, or have different meanings when used in this context. Working toward legislation to curb light pollution in Illinois. Your browser does not support JavaScript, or has "active content" blocked Menu system will not function.
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