Introduction:
Other day a person from eco awareness promotion group preached me to move from Incandescent bulb to CFL saying they were eco-friendly and the Incandescent bulbs where hazards. Innocently enquiring more information of the hazards materials used in Incandescent bulbs and how CFL where safer over their competitor, reveled to me that he was not aware why the CFL is called eco-friendly.
"A typical tungsten filament incandescent lamp usually convert only about 2% of its electric power to visible white light, rest of the energy is converted as heat to provide for warming up your room" – Mallickarjuna.A.S
The CFL & Tube-light are generally called energy saving light. Fluorescent lamps convert more electric power to visible light than does the incandescent lamps. A typical tungsten filament incandescent lamp usually convert only about 2% of its electric power to visible white light, rest of the energy is converted as heat to provide for warming up your room, whereas typical fluorescent lamps convert about 22% of the power input to visible white light. Clearly the CFL is far better in power to light conversation efficacy.
Eco-Safe & Eco-Friendly:
These are two distinct meaning and are always confused as given in my introduction; there are two meaning to talk about eco-bulbs.
1. Power Efficient – Less power is needed, thus less power generation in the powerhouse, so less use of fossil fuel, nuclear, water etc. the government in many countries are forcing its citizens to use CFLs to lower the Carbon Emissions.
2. Environmentally Safe – These bulbs can be disposed to earth safely without fear of chemical hazard. If large quantities of energy-saving light bulbs are allowed to go to landfill, the mercury could contaminate and cause damage to the environment.
"The warm glowing incandescent light bulb of Edison that we are familiar with for about 150 years, which is eco-safe is not talked much today unlike Florescent lamps that uses neurotoxin Mercury (Hg) is popularized as eco-friendly"- Mallickarjuna.A.S
When a bulb industry is doing its marketing talk it's generally about power efficiency, people generally confuse this with Safe Disposal. E-waste disposable or Safe Recycling is still a alien language in many countries and florescent bulb manufacturers are actually not bothered what you do with your used bulbs, because they feel it's the new owners property rights. So in this article I want to emphasis the key difference between Eco-friendly and Eco-safety of light bulbs and the other important parameters required for choosing a light bulb for home/office/shop/street/path lights etc.
The warm glowing incandescent light bulb of Edison we are all familiar with for about 150 years that is eco-safe is not talked much today unlike Florescent lamps that uses neurotoxin Mercury (Hg) is popularized as eco-friendly.
"E-waste disposable or Safe Recycling is still a alien language in many countries and florescent bulb manufacturers are actually not bothered what you do with your used bulbs, because they feel it's the new owners property rights"- Mallickarjuna.A.S
Disposing the Energy Saving Light Bulbs:
Energy Saving Light bulbs function in much the same way as a fluorescent tube. They contain a minute amount of mercury approx 5 milligram of mercury. This mercury allows them to deliver their substantial energy saving benefits. These light bulbs should not be put in the normal household waste. A more environmentally friendly and responsible way of disposal is to ensure that the light bulbs are recycled at the end of their life, either at your local authority Household Waste Recycling Centre or e-waste recycle centre.
Scientists at the Health Protection Agency have reviewed the potential health effects of mercury exposure from broken compact fluorescent light-bulbs. They found the exposure is likely to be very small - and much lower than from other broken mercury containing products such as some types of thermometer and barometers. Professor Virginia Murray, Consultant Medical Toxicologist, said: "Compact fluorescent light-bulbs contain a tiny amount of mercury - roughly enough to cover the tip of a ball point pen. A small proportion of this could be released into a room if the bulb is broken, but this does not pose a health risk to anyone immediately exposed.
"As a precautionary measure, the HPA advise that the room should be ventilated and the bulb cleaned up and disposed of properly."
The clean up should involve:
On hard surfaces wipe the area with a damp cloth, place that in the plastic bag and seal it.
Sticky tape (e.g. duct tape or similar) can be used to pick up small residual pieces or powder from soft furnishings and then placed in a sealed plastic bag.
The plastic bag doesn't need to be air tight, but should be reasonably sturdy. Place it in another, similar bag and seal that one as well (again, this minimises cuts from broken glass). The public should contact the local authority for advice on where to dispose of broken or intact CFLs as they should be treated as hazardous waste.
New Energy Saving Light bulbs and Fluorescent tubes sold today now carry the following informative mark as a reminder that they should be recycled separately.
Energy Saving Light Bulbs:
In the EU, CFL's are rated as either A or B in their energy rating system (i.e. the most energy efficient in their class), with halogen bulbs getting a D-rating, and the old incandescent getting and E or F-rating! They are reported to use as little as 20% of the energy of a standard light-bulb - so reducing running costs of offices and retail outlets greatly!
According to the US Department of Energy, if we all switched our five most-highly used light bulbs to compact fluorescents, we would save enough electricity to shut down 21 power generating plants which is about 800 billion KWh (kilowatt-hours). That means a lot less carbon dioxide, sulfur dioxide, and nitrogen oxides going into the air and causing problems like climate change, acid rain, ozone and contaminated fish. Not to mention the money we'd save on our monthly electric bills.
Choosing for Light Bulbs:
Choosing a light bulb/lamp with fixture requires the following careful considerations:
1. Color Rendering
2. Visible Light Spectrum
3. Color Temperature
4. Power Efficiency
5. Power Factor
6. Life expectancy
7. Start-up Time
8. Light Diffusion
9. Lumens
10. Lux
11. Heat Dissipation
12. Fixture Efficacy
13. Light Pollution
14. Bulb Shape
15. Bulb Base
16. Hazardous Area Safety Light
17. Eco Safety
Comparison of common light bulb
Kelvin color temperature scale and how it relate to the type of lamp & natural light
1. Color Rendering - Color rendering Index CRI is to measure how well light sources render the colors of an object appear to human eye, and how well subtle variations in color shades are revealed. The higher the CRI rating is, the better its color rendering ability and is expressed as a rating from 0 to 100 on the Color Rendering Index.
The test procedure involves comparing the appearance of eight color samples under the light in
question and a reference light source. In short Color Rendering Index is a way of measuring how
well a given light source will make colors appear when viewed under the light source.
2. Visible Light Spectrum - Cover the range of wavelengths from 390 - 750 nm (nanometers). The sun emits most of its radiation in the visible range, which our eyes perceive as the colors of a rainbow. Our eyes are sensitive only to this small portion of the electromagnetic spectrum. Your lighting requirement falls within this range.
3. Color temperature - Is expressed on the Kelvin scale (K), is the color appearance of the lamp itself and the light it produces. Imagine a block of steel that is steadily heated until it glows first orange, then yellow and so on until it becomes white hot. At any particular time during the heating process, if we measure the temperature our block of steel in Kelvins (Celsius + 273) and assign that value to the color being produced. This is the theoretical foundation behind color temperature.
Lamps with a lower color temperature (3500K or less) have a warm or red-yellow/orangish-white appearance. The light is saturated in red and orange wavelengths, bringing out warmer object colors such as red and orange more richly.
Lamps with a mid-range color temperature (3500K to 4100K) have a neutral or white appearance. The light is more balanced in its color wavelengths.
Lamps with a higher color temperature (4100K or higher) have a cool or bluish-white appearance.
One of the most important factors to consider is the psychological impact of a particular color render of a light sources in an environment. Warm light sources are generally preferred for the home, restaurants, hospitality to create a sense of warmth and a comfort feel, while neutral and cool light sources are generally preferred for high-activity areas such as offices, schools, sports arena, supermarkets, security to create a sense of alertness.
4. Luminous Efficiency - Lumen/Watt is the amount of visible light that it produces for a watt of power consumed. The better efficient light-bulbs are generally called eco-friendly and it need not be eco-safe. You take the total # of lumens and divide it by the wattage of the light bulb (lumens/watt). More lumens per watt mean more light for your money.
5. Power Factor - A measure of the effectiveness with which an electrical device converts volt-amperes to watts; devices with power factors (0.90) are "high power factor" devices.
6. Life expectancy – The total life of the lamp, in many case like the CFL/Tube-light the lamp will not fail dead but the luminous intensity will fall drastically over the period of use, the life of this lamps should be declared based on 10% of its intensity lost.
7. Start-up Time – The light bulb start up time, the Incandescent, LED are best known for this, the ESL claims the same. The florescent lamps needs starts to heat the lamp before the electrons strike the florescent coating, hence a delay and difficulty in starting this lamps. The electronic ballast in CFL and Tube-light make the strike almost instantaneous, but you have to pay a premium for it.
8. Light Diffusion – How the light is spread into the room, in some case we require a down-light that just focus as spotlight and some that can give a smooth spread. The tube light gives the best spread for a given room.
9. Luminance - Lumens are a way to measure light density, these units are equal to the number of candles it takes to light a specific area. One lumen actually equals one candles worth of light per square foot of surface area when that candle is exactly one foot away. Whether you are 1 meter away or 100 meters away from a light bulb is still emitting the same amount of lumen output. In other words, Lumens is the means to measure light energy leaving the light bulb.
Lumens is measured by taking a lumen measuring device and taking the average of the lumen rating all around a light source. The lumen is used to express a quantity of light flux: total output of a source, output within a specific angular zone, amount of absorbed light, etc.
Courtesy: Thorlux Lighting
This is called an integrating sphere - and is used to measure the lumens of a bulb more precisely.
10. Lux - A lux or foot-candle (old standard) is a measurement of light at one point. It's measured with a Lux meter. It's a unit that indicates the density of light that falls on a surface. This is what light meters measure. For example, average indoor lighting ranges from 100 to 1,000 lux, and average sunlight outside in the open is about 50,000 lux.
Lux relate only to the task area, not to the lighting equipment or to the geometry of the space. For example, you could create an illumination level of 100 lux on a surface by using a single Spotlight located far away, or by using many cove lights nearby.
lux in general terms is reserved for indicating the amount of light energy actually reaching a given surface.
The higher the measurement the "brighter" the light is at the point measured.
While buying light bulb, it's very important to know the lumens and lux of it. Although it may say how many lumens it puts out, this is merely the lumen output at one foot away. This number will decrease exponentially with every foot the bulb is farther away from the given surface.
Inverse square law: The intensity of light from a point source is inversely proportional to the
square of the distance from the source, so an object twice as far away does not receive 1/2 the energy, it receives 1/4 of the energy.
1 foot = 1² = 1
2 foot = 2² = 4
3 foot = 3² = 9
4 foot = 4² = 16
etc
If you have a light bulb that produces one lumen of illumination over an area of one-square-foot hanging the light from 1 foot above the surface, then you increase the distance to two feet, the light energy reaching it will be 1/4 the intensity, resulting in less lumens, because it is not only traveling downwards, it is spreading out.
11. Heat Dissipation – The amount of heat the bulb will produce when it's operational, there are two type of heat generation one that falls on the object of illumination and the other that the lamp physical produce.
12. Fixture Efficacy – If a fixture is required as is the case for Incandescent/CFL/Halogen bulbs like in the cases of a down lighting fixtures, an LED bulb actually gives out MORE light or is more efficient than CFL bulbs. In the figure-1 below almost half the light the CFL bulb gives off is actually wasted and is reflected back into the ceiling the rest is reflected in front while the LED is directional and all the light is directed downwards where it's usable.
So in this case, the efficacy of the bulbs while they are INSIDE the fixture -
For LED's: 57 lumens per watt (lm/W)
For CFL's: is reduced from 61 lumens per watt to 30 lumens per watt (lm/W) since half of the light is wasted.
Showing Luminary efficacy
13. Light Pollution – Also known as photo pollution or luminous pollution these are excessive or unused light that is emitted or reflected to the environment, typically example is the poorly designed streetlight luminary that emits unwanted or obtrusive artificial light around that distracts the driver of the vehicle. Principally, the illumination of the night sky caused by artificial light sources, decreasing the visibility of stars and other natural sky phenomena.
14. Bulb Shape – There are various bulbs shapes to choose from fig-2 gives a clear picture of what is available as standard fitment.
Courtesy Bravolight Fig-2 Shapes of bulbs to choose from
15. Bulb Base – There are various bulbs shapes to choose from fig-2 gives a clear picture of what is available as standard fitment.
Courtesy Bravolight Fig-3 Lamp Base Size of choose
Courtesy Bravolight Fig-4: The bulb size that you may need
16. Hazardous Area Safety Light – Most neglected and the most important subject. Hazardous area is an area in which an explosive gas atmosphere is present, or likely to be present, in quantities such as to require special precaution for construction, installation and use of electrical apparatus. The exposed incandescent bulb or florescent tube in open space if broken can ignite the explosive gases present in this hazardous area. There are special products manufactured for such application. Many categories of safety, classification and standard are applicable for these products, read the relevant document pertaining to this subject.
Fig-6: Hazardous Area Lamps
17. Eco Safety – No hazardous compound should be used, such lamps can be disposed without special care. CFL, Tube-light has mercury and other matters that need to be properly taken care by specialized reprocessing carried out by the WRC "Waste Recycling Centre".
Light Technologies Available in Present & in Future
Luxim Plasma: Silicon Valley's Luxim has developed this new technology LUXIM has patented a product design and production method that solves problems inherent to conventional lighting products. Where conventional bright lamps use metal electrodes to discharge electrical energy into a gas, LIFI™ perfects a technology by which RF (Radio Frequency) energy is injected into a sealed gas capsule emitter. Without degradable electrodes, unprecedented levels of lighting stability and lifetime are possible. In addition, the flexible choice of material in the emitter creates breakthrough levels of spectral quality approaching that of the sun itself by emanating red, green, blue and almost all wavelengths in between. The mechanism is as if to make a small sealed light bulb without a metal connector and instead energize it with a closely placed antenna.
In contrast with almost all other lighting sources which use electrodes for light generation, Luxim Plasma uses a different technology. Luxim Plasma light consist of three major components namely
- An RF amplifier
- Antenna
- Resonant Cavity
The radio frequency amplifier pumps RF waves to an antenna inside a resonant cavity. The interaction between the waves and the crystal cavity convert trapped gases into plasma. "The structure creates a concentrated electrical field in response to a standing wave," explains Julian Carey, Vice President of sales at Luxim. "It creates plasma inside a miniature quartz capsule."
Electron Stimulated Luminescence (ESL): Lights can last up to 6,000 hours, about three to four times the lifespan of incandescent and comparable to CFLs. They produce 50 percent less heat than incandescent.
The ESL bulbs contain an electron source that fires electrons at a proprietary luminescent phosphor, which then glows. The screw-in apparatus is encased in standard light-bulb glass. The company says its ESL bulbs would produce light that's "essentially indistinguishable" from incandescent, contrasting it with the greenish or bluish light from CFLs and LEDs. These bulbs however require electronics like in the case of CFL, Led etc. the company claims they have integrated an optimized electronics within the lamp which means that one can directly replace an incandescent bulb without any changes.
To contrast:
- Incandescent bulbs heat a filament to generate light.
- Compact Fluorescent Lights (CFL) sends a current through a mercury vapor that emits UV light to excite a phosphor.
- Light Emitting Diodes (LED) create light by electrically stimulating a semiconductor material
ESL Lighting Technology uses accelerated electrons to stimulate phosphor to create light, making the surface of the bulb "glow". ESL Technology creates the same light quality as an incandescent but is more energy conserving. There is no use of the neurotoxin Mercury (Hg) in the lighting process.
Safe as a lighting source, the ESL Technology fits neatly into classic light bulb shapes similar to those familiar to consumers everywhere. This eliminates the need to bend the technology into an unusual, twisted spiral shape (CFL) or have costly and heavy heat dissipation designed into the bulb housing (LED).
Fig-7: Color Temperature and guideline for use in an environment
O-LED: OLEDs are a flat light source, emitting diffuse light from a potentially large active area. They do not need light distribution elements, thus reducing the cost for the whole lighting panel. In contrast, LEDs as main competitor are a point source technology which needs light distribution elements to achieve flat panel lighting. Additionally OLEDs use low peak brightness on large area, LEDs provide very high brightness on small area. Due to this fact, LEDs are optimal for point-like light sources, OLEDs are suitable for large area flat light sources. Using large-area OLED with higher efficiency will allow complete lighting solutions based on OLED technology. OLED will substitute existing lighting technologies, but will mainly generate new applications, owing to the unique properties of large-area diffuse light generating with adjustable color. Starting in the near future, OLED lighting will boost the OLED fabrication worldwide. The market research company IDTechEx expects already for 2011 a billion dollar market.
Fig-9: O-LED Flat light
the technology has several advantages over that of conventional lighting. First among the advantages is slimness. The thickness of OLED panels for lighting applications could reach less than 1mm. Such a characteristic could allow OLED lighting placed directly on ceilings rather than hang from them. In addition, flexibility is another advantage, which may allow OLED lighting to be used when designing for spaces with limited conditions.
Conclusion:
The technology is in a fast phase and revolutionary changes in LEDs, ESLs, Luxim Plasma and many others that are on the way to the market, one as to compromise with technologies, buying cost, operational cost along with the safety of use and disposal.
"The most important criterion for the customer is cost and it's the least addressed topic today by the LED manufacturers" – Mallickarjuna.A.S
Studying the various technology's that are emerging it makes me think that LED would be used for focused application that can have vibration and mainly in all Low voltage DC sources even as we speak AC operated LEDs are under development and if these can be made to work without dedicated LED drivers than they do have a edge over others. Many LED lighting require special light fitting and are not directly retrofitted in existing luminary this require more investment from the user. The aluminum heat-sink that is very essential for removing heat from the power LEDs takes up space and add extra weight to these lamps. The most important criterion for the customer is cost and it's the least addressed topic today by the LED manufacturers maybe because of technological process or raw material cost issues or both. Right now cost/lumen ratios are very high to make any meaning full comparison with other technologies. Significant improvements are needed in the lifetime capability of LED drivers for all this to happen. "It is all very well saying that we can get LEDs with lifetimes approaching 50K OR 100K hours of operation, but the important LED drivers are getting nowhere near to that and this is especially a major issue in countries with poor power quality.
The streets may be dominated by the Luxim Plasma as its small, has higher brightness producing capability, power efficient, require luminary does not require ballast circuit to start-up (but requires other circuit to make it operate).
ESL (Electron Stimulated Luminescence)could be more appropriate for replace CFLs and tube-lights because they are almost same size, more efficient nonhazardous and dimmable with normal dimmer controls thus saving more power.
"At the time I experimented on the incandescent lamp I did not understand Ohm's law." - Thomas Alva Edison
Fig-10: Lamp type vs. Lumen/Watt comparative chart
Lumens, also known as luminous flux, is the measure of the perceived power of light from a natural or artificial light source. In simple terms it is the measurement of how bright a bulb or tube is. Whether you are 1 meter away or 100 meters away from a light source it is still emitting the same amount of lumens.
Sun: traveling 93 million miles before getting to earth, the suns lumen output still reaches 5,000 lumens per square foot.
Fig-11: Inverse Square Law
