Uploaded at Friday, November 17 2017 06:26:09 for Lighting Fixtures by Elizabeth Wortham
In the mid-19th century, as gas lighting caught on, branched ceiling fixtures called gasoliers (a portmanteau of gas and chandelier) were produced, and many candle chandeliers were converted. By the 1890s, with the appearance of electric light, some chandeliers used both gas and electricity. As distribution of electricity widened, and supplies became dependable, electric-only chandeliers became standard. Another portmanteau word, electrolier, was formed for these, but nowadays they are most commonly called chandeliers. Some are fitted with bulbs shaped to imitate candle flames, for example those shown below in Epsom and Chatsworth, or with bulbs containing a shimmering gas discharge. The world's largest English Glass chandelier,(Hancock Rixon & Dunt and probably F. & C. Osler) is located in the Dolmabahçe Palace in Istanbul. It has 750 lamps and weighs 4.5 tons. Dolmabahçe has the largest collection of British and Baccarat crystal chandeliers in the world, and one of the great staircases has balusters of Baccarat crystal. More complex and elaborate chandeliers continued to be developed throughout the 18th and 19th centuries, but the widespread introduction of gas and electricity had devalued the chandelier's appeal as a status symbol.
Extensive luminaire photometric designing calls for consideration of the amount of functional light present, the energy expended, as well as the aesthetic impact supplied by the lighting system. Some buildings, like surgical centers and sports facilities, are primarily concerned with providing the appropriate amount of light for the associated task. Some buildings, like warehouses and office buildings, are primarily concerned with saving money through the energy efficiency of the lighting system.
An important property of light fixtures is the luminous efficacy or wall-plug efficiency, meaning the amount of usable light emanating from the fixture per used energy, usually measured in lumen per watt. A fixture using replaceable light sources can also have its efficiency quoted as the percentage of light passed from the "bulb" to the surroundings.