GC: n
CT: Daylighting is recognized as an important and useful strategy in the design of energy efficient buildings. It is particularly useful in hot climates since it reduces the use of artificial lighting and thus electricity demand.
Luminous efficacy is the parameter used to determine outdoor illuminance. In fact, many regions of the world work on this parameter to meet the needs imposed by problematic environments (from a meteorological point of view). For example, illuminance values (in lux or lm.m-2) can be simulated from the solar irradiance (W.m-2) and luminous efficacy. Therefore, it is important to know theses values of luminous efficacy for a given location and this is the reason for this study at Reunion Island.
S: http://arxiv.org/pdf/1212.5259 (last access: 13 February 2015)
N: 1. luminous (adj): early 15c., “full of light,” from Latin luminosus “shining, full of light,” from lumen (genitive luminis) “light,” related to lucere “to shine” (see light (n.)). Related: Luminously.
efficacy (n): 1520s, from Latin efficacia “efficacy, efficiency,” from efficax (genitive efficacis) “powerful, effectual, efficient,” from stem of efficere “work out, accomplish”. Earlier in same sense was efficace (c.1200), from Old French eficace (14c.), from Latin efficacia; also efficacite (early 15c.), from Latin efficacitatem.
2. The luminous efficacy is a light engineering term for the measure of the rate at which a lamp is able to convert electrical power (watt) to light (lumen). The luminous efficacy is therefore expressed in lumens per watt (LPW).
3. The luminous efficacy of a light source is defined as the light source’s lumen value against energy consumption. When the consumption of other components in the luminaire is included (ballast, emergency lighting etc.) we call this the “system efficacy”.
Symbol: H.
Unit: Lm/W.
Symbol: Η = φ/P.
4. The light sensitivity of the normal human eye has been studied extensively. The response of the eye as a function of frequency is called the luminous efficacy of the eye. It has been tabulated for both the light-adapted (photopic) case and the dark-adapted (scotopic) case.
S: 1. OED – http://www.etymonline.com/index.php?allowed_in_frame=0&search=luminous+efficacy&searchmode=none (last access: 13 February 2015). 2. TERMIUMPLUS. 3. http://glamox.com/uk/lighting-technical-definitions (last access: 13 February 2015). 4. http://hyperphysics.phy-astr.gsu.edu/hbase/vision/efficacy.html (last access: 13 February 2015).
SYN: light efficacy
S: TERMIUMPLUS
