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However, ongoing Ongoing research has dramatically improved the efficiency of LEDs; although this is only starting to appear in production versions. LED efficiency improved dramatically in 2006. Nichia Corporation of Japan demonstrated white LED prototypes with an efficiency of 113 lumens per watt. The industry target is 100 lumens per watt, which is better than fluorescent tubes. The Nichia work was partly funded by the UK Department of Trade & Industry. (White LEDs are actually blue in wavelengths of 450 nm – 470 nm.) However, as of December 2015 there is still wishy-washiness in the claims for LED efficiency. <ref>https://theconversation.com/the-scientific-reason-you-dont-like-led-bulbs-and-the-simple-way-to-fix-them-81639</ref> <ref>http://www.greentechmedia.com/articles/read/can-leds-be-nearly-as-cheap-as-incandescents-by-2020</ref> In addition, LEDs produce no discernible heat and are more robust than fluorescents and incandescents. They LEDs have become the lighting of choice for many marine applications.
In the berths, galley and dinette use low-voltage white or blue LEDs as spot or reading lights. Their cooler temperature will make enclosed spaces more comfortable. For courtesy lighting in corridors and companionways, use blue LEDs.
→LED
= Lighting Design =
[[:{{TALKPAGENAME}}|Discussion/Comments]]
== Summary == To reduce energy consumption all lighting except in the engine room should be DC, fitted with dimmer switches where appropriate. The engine room can have dual DC and AC fluorescent lighting. The latter will make it easier to work in the engine room when connected to shore power, especially if the DC system must be disconnected. The long tube length of fluorescents will give more even illumination than other types of lighting. However, the DC lighting should give sufficient illumination for work at sea. The ideal daylight lamp for ambient lighting will have a colour temperature of 2700 Kelvin (K) at a wavelength of 555 nanometres (nm), a Colour Rendering Index (CRI) greater than 84, and produce 100 lumens per input watt. In the pilothouse, use blue-green (507 nm) or turquoise (495 nm) LEDs for night vision. Use dim white for reading colours on maps. == Lighting Criteria ==
All of the light types discussed below are available in low-voltage DC. Dimmer switches can be used with most tungsten and halogen lights but only certain types of fluorescent. Make sure the dimmer switch is compatible with the light and its wattage. In a marine environment, use double-pin ungrounded lamps for all types.
* Application (ambient, accent, task and utility)
It’s tempting to start by discussing the application of lights, because this is like not running out of hot water or never having the toilet plug. You don’t want to spend cruising hours pissed off because you can’t read comfortably (or whatever). But to make the best choices for different applications, we have to take the long road through the technology of lighting. Illumination and colour are the main aspects of lighting. Energy efficiency obviously affects the load on the electrical system but taken in isolation will not deliver the most comfortable living environment.
== Illumination ==
Illumination is measured in lumensusing an illuminometer such as [http://www.sekonic.com/products/i-346/overview.aspx Sekonic]. The [https://en.wikipedia.org/wiki/International_System_of_Units SI ] measurement of illumination is lux, or one lumen per square metre (about 1/10 foot-candle). A lumen is the amount of light falling on a surface. A foot-candle is one lumen distributed over one square foot.
The illumination required for casual reading is 200-550 lumens/sq metre. The standard for office desks is 500 lumens. Some general guidelines for comfortable living are given in the below table. These are generally in excess of [https://www.abycinc.org/ ABYC] standards but you should check when you build.
<table border="1" width="80%>
<caption>Recommended Illumination</caption>
<tr><th>Area</th><th> Lumens/sq metre<br>(lux)</th><th> Lumens/sq foot<br>(ft-candle)<br>(rounded up)</th></tr>
<tr><td> Heads/Companionways </td><td>200-500</td><td>19-47</td></tr>
<tr><td> Berths </td><td>550-1100</td><td>52-103</td></tr>
The colour of light falling on an object affects our perception of the colour of the object (a very complex subject in itself). The colour of a light is expressed as the correlated colour temperature (CCT) or the Colour Rendering Index (CRI).
CCT is measured in degrees Kelvin. CRI is measured on a scale of 0-100, where a light source with 100 CRI is best at producing vibrant colour in objects. A higher CRI rating typically denotes a higher quality lamp. A CRI of 84 or better gives very little shift in an object's colour. Incandescents have an index of 95-100, ; and tri-phosphor fluorescent runs 84-88. Most LEDs [http://www.cnet.com/news/shining-a-light-on-high-cri-led-bulbs/ score in the 80s], but some are [https://en.wikipedia.org/wiki/High_CRI_LED_lighting available with 90].
The main colour spectrum of a lamp determines how it makes us feel in an interior space. Colour spectrum is related to a lamp’s temperature. Colour temperature can be soft and comfortable for relaxing or sharp and precise for work environments. The higher the temperature, the cooler the colour of the lamp. For example, a colour temperature of 3000K is warm while 4100K is cool. Indoor lighting is typically 2700K Outdoor lighting is 6500K.
=== Daylight ===
Blue light is important during the day. Essentially we are blue-light detectors when it comes to keeping our internal clock well adjusted. This is especially important in the winter when blue-light levels might not be sharp enough to maintain our 24-hour clock.<ref>https://justgetflux.com/research.html</ref>
Light of around 555 nanometres is accepted as the most efficient level of light for daytime vision. But recent research has shown that we also have biological receptors for non-visual response peaking in the blue wavelength range of 446-477 nanometres, a range abundant in clear daylight. Researchers at Brown University in 2002 discovered that non-visual ganglion cells in the eye detect sky-blue light to set our internal clock.
Daylight has an abundance of wavelengths at 446-477 and in the 555 nanometre range, satisfying both perceptual and biological and perceptual demands. The challenge is to develop lighting solutions that will perform like daylight.
The choice of colour is controversial, in part because many colours we perceive are not interpolated but are ‘invented’ by the brain. The theory is that some colours enhance low-light vision provided by the cones in the eye. The eye also has rods, used for normal intensity light. Originally, it was believed that the cones, occupying a narrow slice in the centre of the retina, were red sensitive, so using red lighting would enhance night vision. But the cones are blue-green (507 nm) sensitive; although the fovea, an even more narrow slice at the centre of the cones is very red sensitive.
Energy efficiency is the amount of light output generated per watt of input energy consumed. This is important because it directly affects the size of our electrical system. The main choices in types of light in order of efficiency are:
* Incandescent (Tailored Spectrum)
* LEDs post-2007
* Fluorescent
* Halogen
* Incandescent(Standard)
* LEDs pre-2007
=== LED ===
LEDs have had a very high profile in the energy market for some time. But until recently they did very poorly in energy efficiencyand were very expensive. Fluorescents were best, producing about 30-100 lumens per watt, while halogens produced 10-18, and incandescents 8-15. In 2014 mid-market colour-corrected LEDs were running 53-59 lumens per watt; while uncorrected ones were in the 80s. [[File:LEDEfficiency.jpg|thumb|250px|left|© Department of Trade & Industry, UK Government]] Newer LEDs are grouped in clusters with diffuser lenses which have broadened the applications for their use. Without a difuser LEDs are very directional.
Before 2007, LEDs used less than 10% of the energy of an incandescent lamp, but did not produce as much light output per watt of energy consumed. To disguise this, some vendors rated LED efficiency as the amount of light output generated per watt of total output energy instead of the input energy.
LEDs have a long life (100,000 hours) and low heat output. They give off a soft natural directional light in white, red, green or blue. White or blue are used for reading, e.g., a reading spot lamp. Red, green or blue are used for night vision.
In a low voltage DC system, their driving system is simple and cheap compared to a fluorescent, which requires an oscillating ballast circuit. LEDs use a simple voltage-dropping resistor. They are tough and resistant to shock and vibration. They are safe near explosive gases and liquids. In a marine installation, use a dual-pin ungrounded LED. Until recently LEDs were rated in millicandela (mcd), as measured at the light source, not lumens. This made direct comparisons with other light types fuzzy. (One lumen is approximately 79.5 mcd [7].)
Now that LEDs are more competitive, manufacturers are stepping up and also rating them in lumens.<!--<ref>https://www.scientificamerican.com/article/the-scientific-reason-you-dont-like-led-bulbs-mdash-and-the-simple-way-to-fix-them/</ref>-->
=== Fluorescents ===
Prior to breakthroughs in the efficiency of LEDs, fluorescent lamps were the clear winners in energy efficiency. They last about 34,000 hours and have low heat output.
Fluorescents are humidity and temperature sensitive and may not work under -10 degrees °F (-23.3 °C) or over 120 °F (48.8 °C).
Fluorescents have electrodes at both ends of a tube coated inside with phosphor. Inside the tube, a gas contains argon and mercury vapour. A stream of electrons flows through the gas from one electrode to another. This excites the mercury atoms, giving off ultraviolet photons. In turn these excite the phosphor, giving off visible light.
==== Cold Cathode Fluorescents ====
Cold cathode fluorescents (CCF) are similar in construction to neon tubes and have up to 25,000 hours of service life. They are readily dimmable. Look for models that are listed for marine, [http://ulstandards.ul.com/standard/?id=234 RV UL-234], [http://www.csagroup.org/ CSA ] and [http://ec.europa.eu/growth/single-market/ce-marking/ CE ] (Europe), and meet the Ignition Proof test requirements of the United States Coast Guard, as stated in [http://www.gpo.gov/fdsys/granule/CFR-2006-title33-vol2/CFR-2006-title33-vol2-sec183-410 Title 33 CFR 183.410]. CCFs are more efficient than other fluorescents but the tri-phosphor fluorescents have the most pleasing colour.
==== Compact Fluorescent ====
Compact fluorescent lights (CFL) are more robust than tubes. They use only a small amount of mercury, typically less than 5 mg per bulb. General Electric [http://www.gereports.com/say-goodbye-say-hello-ge-stops-making-cfls-says-go-go-go-to-leds/ will phase out CFLs] by the end of 2016.
=== Halogen ===
Sir Joseph Swann invented them in the 1870s; although most Americans credit Thomas Edison. Watch for improved versions using deposited carbon nanotube filaments by 2009. This may not matter since many governments are banning tungsten bulbs. Australia is targeting 2010, the USA 2012-2014.
An experimental proof-of-concept tailored-spectrum incandescent has shown natural light at close to maximum efficiency (40%) for a luminous device.<ref>http://www.telegraph.co.uk/news/science/science-news/12093545/Return-of-incandescent-light-bulbs-as-MIT-makes-them-more-efficient-than-LEDs.html</ref> In the device the filament is surrounded by a cold-side nanophotonic interference system optimized to reflect infrared light and transmit visible light for a wide range of angles. It could become a light source that reaches luminous efficiencies (∼40%) surpassing existing lighting technologies, and nearing a limit for lighting applications.<ref>http://www.nature.com/nnano/journal/vaop/ncurrent/full/nnano.2015.309.html</ref>
== Application ==
=== Ambient Lighting ===
For general ambient lighting throughout, use ceiling mounted, dimmable, low-voltage DC tri-phosphor or cold-cathode fluorescents will give for the best most pleasing results. Select tri-phosphor or cold-cathode depending on how you feel about natural colour. If you are not that picky use difused LEDs. Put dimmer switches everywhere except in companionways and the engine room.
=== Accent Lighting ===
For accent lighting, use small low-voltage DC LEDs or halogens with dimmers. Don’t use halogens in the berths, galley and dinette where close proximity makes their heat uncomfortable. Because of their very high heat output, ensure halogens are in proper enclosures and at least six inches away from objects.
=== Task Lighting ===
In the galley, put fluorescent DC cold cathode fluorescents or difused LED lighting under the cupboards, hidden behind a valence, to provide task lighting on a separate switch. Don’t use a dimmer here.
In the engine room, use DC LEDs in general but have a separate circuit for AC cold cathode fluorescents for use with shore power. Provide outlets for both DC and AC trouble lights. In the berths, galley and dinette use DC low-voltage white or blue LEDs as spot or reading lights. Their cooler temperature will make enclosed spaces more comfortable. For courtesy lighting in corridors and companionways, use blue LEDs.
=== Utility Lighting ===
For utility lighting such as external spotlights, use halogen. Dual-head emergency lights, with battery backup, are available in all light types. But on balance use the newer LEDs for emergency lights. Dual-head (dual lamp) provides redundancy.
In the pilothouse, use blue-green (507 nm) or turquoise (495 nm) LEDs for night vision. Eight percent of males are red-green deficient [8], and will be groping blindly with low-level red or green night vision lights. (Women have an extra strong response to red-orange.) Even a higher percentage may have temporary alterations in perception of blue under varying conditions. Most people over 45 suffer from reduced light transmission into the eye.
Red-green deficiency is the most common type of colour blindness (99% of cases). A genetic glitch causes the red and green sensing cones to overlap more than normal. This makes it difficult to distinguish between certain shades of green and brown, red and brown, and yellow and orange. Pinks can appear gray, purple and blue get mixed up a lot, and a green light may appear bright white.<ref>http://arstechnica.com/science/2016/02/seeing-in-techicolor-one-month-wearing-enchromas-color-blindness-correcting-glasses/</ref> [[Category:ElectricalLightingGeneral]] [[Category:ElectricalLightingSystemsElectricalLightingTypes]]