Lighting Technologies - Revision history

Ranisha: /* Power of the Lighting Device */

2015-09-08T14:51:24Z

Power of the Lighting Device

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Ranisha: /* Repetitive Summary */

2015-09-08T14:46:23Z

Repetitive Summary

Ranisha: /* Luminous Flux */

2015-09-08T14:42:15Z

Luminous Flux

Ranisha: /* Opt for an Ideal Lamp Type */

2015-01-28T08:30:22Z

Opt for an Ideal Lamp Type

Ranisha: /* Consider the Lighting Options */

2015-01-28T08:30:07Z

Consider the Lighting Options

Ranisha at 08:29, 28 January 2015

2015-01-28T08:29:09Z

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Wiki Gardener at 11:03, 19 January 2015

2015-01-19T11:03:36Z

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Wiki Gardener: /* Further Information */

2014-12-29T13:52:54Z

Further Information

Wiki Gardener: /* Light Emitting Diodes (LEDs) */

2014-12-29T13:52:09Z

Light Emitting Diodes (LEDs)

Wiki Gardener at 13:45, 29 December 2014

2014-12-29T13:45:08Z

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@@ Line 36: / Line 36: @@
 *The total light flux in transit is measured in lumens (1 lumen = 1 candela X steradian);
 *The amount of light received per unit of surface area is measured in lux (1 lux = 1 lumen/square meter).
 <br/>
@@ Line 44: / Line 45: @@
 ''Tab.1: Typical lighting levels in day to day life''
-<div style="text-align: center">
+{| cellspacing="0" cellpadding="0" border="1" style="width:100%;"
 |-
-| style="width: 59%;  background-color: rgb(204, 204, 204)" | '''Outdoor'''
+| style="background-color: rgb(204, 204, 204)" | '''Outdoor'''
-| style="width: 40%;  background-color: rgb(204, 204, 204)" | '''Illuminance (lux)'''
+| style="background-color: rgb(204, 204, 204)" | '''Illuminance (lux)'''
 |-
-| style="width: 59%" | Bright sun
+| Bright sun
-| style="width: 40%" | 50,000 – 100,000
+| 50,000 – 100,000
 |-
-| style="width: 59%" | Hazy day
+| Hazy day
-| style="width: 40%" | 10,000 – 50,000
+| 10,000 – 50,000
 |-
-| style="width: 59%" | Full moon
+| Full moon
-| style="width: 40%" | 0.05 - 0.2
+| 0.05 - 0.2
 |-
-| style="width: 59%;  background-color: rgb(204, 204, 204)" | '''Indoor'''
+| style="background-color: rgb(204, 204, 204)" | '''Indoor'''
-| style="width: 40%;  background-color: rgb(204, 204, 204)" | '''Illuminance (lux)'''
+| style="background-color: rgb(204, 204, 204)" | '''Illuminance (lux)'''
 |-
-| style="width: 59%" | Office or workshop
+| Office or workshop
-| style="width: 40%" | 200 - 300
+| 200 - 300
 |-
-| style="width: 59%" | Reading Area
+| Reading Area
-| style="width: 40%" | 300 - 500
+| 300 - 500
 |-
-| style="width: 59%" | Class Room
+| Class Room
-| style="width: 40%" | 300
+| 300
 |-
-| style="width: 59%;  background-color: rgb(204, 204, 204)" | '''Health Centres'''
+| style="background-color: rgb(204, 204, 204)" | '''Health Centres'''
-| style="width: 40%;  background-color: rgb(204, 204, 204)" | '''Illuminance (lux)'''
+| style="background-color: rgb(204, 204, 204)" | '''Illuminance (lux)'''
 |-
-| style="width: 59%" | Examination Area (Spot Light)
+| Examination Area (Spot Light)
-| style="width: 40%" | <font size="2">500</font>
+| <font size="2">500</font>
 |-
-| style="width: 59%" | Surgery Room (Spot Light)
+| Surgery Room (Spot Light)
-| style="width: 40%" | 2000
+| 2000
 |-
-| style="width: 59%;  background-color: rgb(204, 204, 204)" | '''Domestic Lighting'''
+| style="background-color: rgb(204, 204, 204)" | '''Domestic Lighting'''
-| style="width: 40%;  background-color: rgb(204, 204, 204)" | '''Illuminance (lux)'''
+| style="background-color: rgb(204, 204, 204)" | '''Illuminance (lux)'''
 |-
-| style="width: 59%" | Living Room
+| Living Room
-| style="width: 40%" | 100 - 300
+| 100 - 300
 |-
-| style="width: 59%" | Kitchen Working Area
+| Kitchen Working Area
-| style="width: 40%" | 300
+| 300
 |-
-| style="width: 59%" | Corridors
+| Corridors
-| style="width: 40%" | 50 - 100
+| 50 - 100
 |-
-| style="width: 59%" | Good street light
+| Good street light
-| style="width: 40%" | 20
+| 20
 |}
-</div><br/><br/>
 = Lighting Technologies<br/> =

@@ Line 15: / Line 15: @@
 == Luminous Flux ==
 Luminous flux (or luminous power) is the quantity of light energy emitted in all directions. The unit of luminous flux is '''''lumen (lm)'''''. One lumen is the luminous flux of the uniform point light source that has luminous intensity of 1 candela (cd) and is contained in one unit of spatial angle (or 1 steradian).
 Steradian is the spatial angle that limits the surface area of the sphere equal to the square of the radius. If the radius of the sphere is 1 metre, which implies its area to be 4πr², then the luminous flux of the point light source of 1 candela is 4π lumens, as shown in Figures 2 & 3.
+[[File:Steradian.jpg|left|500px|thumb|Figure 2 & Figure 3|alt=Figure 2 & Figure 3]]<div style="clear: both"></div>
 For instance, a light source can be emitting light with an intensity of one candela in all directions, or one candela in just a narrow beam (as in most LEDs). The intensity is the same but the total energy flux from the lamp, in lumens, is not the same. The output from a lamp is usually quoted in lumens, summed over all directions, together with the distribution diagram in candela.

@@ Line 585: / Line 585: @@
 The lower power requirements, higher durability and rapid advancements, are projected to offer competitive long-term operating costs, making LED technology more attractive for lighting solutions in the developing world.
-<br/></div>
 == <span><span><font size="3">Preview the Costs Involved</font></span></span><br/> ==
 Having considered various selection criteria for different technologies, it is important to have a preview of the costs involved in considering a specific option. It would be of advantage to calculate the total operating costs for one full year, for each lighting option, which would reflect the cost of the lamp, cost of energy, cost of labour and maintenance, as shown in Tab. 5 (see attached excel calculation sheet).Tab. 5 serves as a guide with some typical lighting options, based on realistic values of the various specifications. The ultimate aim of Tab. 5 is to compute the annual operating costs of a lamp type.<br/>

@@ Line 563: / Line 563: @@
 <br/>
-</div>As lamps of a given wattage are available, it is possible to determine the exact amount of lighting that would reach the surface to be illuminated, with the lamp type considered using the procedure mentioned. If more illumination is required, then, it is necessary to consider the lamp types of higher power (or wattage) rating or consider a luminaire or a concentrator for the lamp. However, it is always possible to check the level of illumination on a given surface, simply by using a LUX meter.<br/></div><br/></div>
+</div>As lamps of a given wattage are available, it is possible to determine the exact amount of lighting that would reach the surface to be illuminated, with the lamp type considered using the procedure mentioned. If more illumination is required, then, it is necessary to consider the lamp types of higher power (or wattage) rating or consider a luminaire or a concentrator for the lamp. However, it is always possible to check the level of illumination on a given surface, simply by using a LUX meter.<br/></div><br/>
 == <span><span><font size="3">Opt for an Ideal Lamp Type</font></span></span><br/> ==
 Based on the procedures mentioned in the preceding paragraphs, it is easier to decide on a lamp type for a given situation. However, it should be noted that some lamps are best suited for certain applications.As a rule, fluorescents might be ideal for use in homes, work areas while Halogen lamps and LED based lamps might be ideal for focussed, task based lighting. Low pressure sodium lamps may be considered for parking areas. It is better to avoid the incandescent lamps as much as possible. It is also important to look at the availability of the lamp types in the market, for easy replacement.<br/>

@@ Line 1,032: / Line 1,032: @@
 *<span><span></span></span>Initial investment required for the lighting option.
 </div><br/>
 = Further Information<br/> =
 <div class="mw-collapsible mw-collapsed">
 *[[:File:Lighting technologies.pdf|PDF-Version]]
-*[[Light-emitting diode|Light-emitting Diode]]<br/>
+*[[Light_Emitting_Diode_(LED)|Light Emitting Diode (LED)]]<br/>
 *[[Lighting|Lighting]]
 <br/></div>
 = References<br/> =
 <references />
 [[Category:Lighting]]

@@ Line 188: / Line 188: @@
 <br/></div>
 === Light Emitting Diodes (LEDs)<br/> ===
-<div class="mw-collapsible mw-collapsed">[[Light-emitting_diode|Light Emitting Diodes (LEDs)]] are semiconductor devices similar to p-n junction diodes, specially engineered to emit visible light of a particular wavelength, giving out a specific colour.
+<div class="mw-collapsible mw-collapsed">[[Light_Emitting_Diode_(LED)|Light Emitting Diodes (LEDs)]] are semiconductor devices similar to p-n junction diodes, specially engineered to emit visible light of a particular wavelength, giving out a specific colour.On supplying electrical power to an LED, electrons are made to “fall” from a high energy level to a low energy level inside the semiconductor material, releasing some energy, which is perceived as <span>visible light.</span>
 LEDs are usually monochromatic and are very energy-efficient and therefore used extensively as indicator lamps on many electronic devices. Red, green, and orange LEDs as indicator lamps are usually well known. They are usually operated with no more than 20 – 70 mW of electrical power and not adequate for lighting purposes. However, the development of bright white LEDs advanced rapidly in recent years and is achieving fast access to the market. In 1999, the first 1 W white LEDs came on the market. In 2002, first 5 W models were available.
@@ Line 201: / Line 200: @@
 <br/>
-<p style="text-align: center">''Fig. 4: Relation between ambient temperatures and LED life''</p>[[File:LED life.png|thumb|center|305px|Relation between ambient temperatures and LED life]]
+<p style="text-align: center">''Fig. 4: Relation between ambient temperatures and LED life''</p>[[File:LED life.png|thumb|center|305px|Relation between ambient temperatures and LED life]]<br/>
 LEDs due to their construction emit light only in one direction and hence are more effective in task based or focussed lighting such as in table lamps, torch lights, etc.
@@ Line 210: / Line 207: @@
 <br/></div>
 = Synopsis of Efficiency and Costs of Various Lighting Technologies<br/> =
 <div class="mw-collapsible mw-collapsed">Having analysed the various technical factors governing the lighting technologies, both flame-based as well as electricity-based ones, it is now worthwhile to have a brief synopsis focussing on efficiency and costs of all the lighting technologies in a single table, as shown in Tab. 3. Some details are discussed in the following paragraphs.