Recently , Our gorverment authorities, as part of a national pilot exercise on energy saving, replaced 16 unit of street " high pressure sodium lamps" with LED bulbs. The LED bulbs are said to have electricity bill " 18 % energy saving " properties saving up to one millon dollars on monthly. Subsequent plans to replace 100 K unit of street lamp. The plan is to extend replacement of lamp bulbs with LED to include fluorescent lighting used in the public housing, to a tune of 340K units. This move is said to save another five million yearly on electricity bills. I feel that this a knee jerk reaction to the energy saving properties LED lighting has. It is an abuse of the LED technolgy. What do you thinks ? Can any members commemt ? Thanks for advice and reply.
LEDs keep getting better. If they are packaged properly, they will be both efficient and very reliable. Rolling three guys in a cherry-picker truck to replace bulbs in street lights and traffic lights is terrifically expensive, too.
There is a lot of history of new lighting technologies causing disappointments. Sometimes, and especially in many cases with LED replacement lighting, the claims of gain in energy efficiency are overstated or half-truths. Also, the replacement lighting units sometimes don't produce the same quality of light, or the same light distribution pattern, as that produced by what was replaced.
Those in charge of procuring lighting units of a different technology should check out units already installed for customers who are happy with them. Preferably, a few existing units should be retrofitted on a local pilot study basis.
I have seen a lot of stories of replacing HID lighting units with LED ones that sounded to me too good to be true, especially considering the efficiency of the best *feasibly and economically available* LEDs that could have been used in units made before the times when some of these stories came out. One thing: I have not seen much in increase in claims of energy efficiency improvement by going with LED here in the past 4 years, while LED efficiency did increase significantly in that time. This makes me think that the claims "were not quite right" back then, maybe to put it mildly, and I would not count on them being "fully true" now until tested/verified.
Things to watch out for:
Comparison of brand new clean replacement units with aged/dirty existing units
Overstating energy consumption rate of existing units
Overstating light output of replacement units for any or any combination of several reasons, some of them ones of incompetence rather than dishonesty
Overstating benefits of different color or different spectrum of the light from the replacement units
LED life expectancy figures turn out to be optimistic (less likely when the LEDs themselves are by a *big name major established LED manufacturer* that publishes a datasheet, and the customer verifies that the LEDs are reliably not having LED current or relevant temperature (such as heatsinkable surface of the LEDs or adjacent heatsink) pushing or exceeding limits specified in the datasheet for good life expectancy. (Preferably the datasheet states for fading by typically no more than to 70% of "initial" light output at 50,000 hours.) Watch out for how non-contact thermometers read bare metal, and how any thermometer used by a salescritter or used in a manner recommended by a salescritter can read low for what such salescritter is selling.
However, I actually do not like HPS lamps. I like metal halide better for effectiveness of illumination, and I like LED better still when done right and done with honest and verifiable numbers, if the numbers add up to be advantageous.
It appears to me that LED may be just now becoming preferable to most currently existing HID lamp technology for most streetlighting. If not, maybe just a couple more years now!
Have a look at my previous article in this thread.
Meanwhile, I do see a major difference here between streetlights and traffic lights. For streetlights, LED replacements are competing mostly against lamps achieving 70-110 lumens per watt and mostly lasting 3-6 years before needing replacement of a lamp costing $15 or less FOB in quantities that municipalities would purchase. HPS is mostly achieving
5-plus, maybe often largely 7 years now before needing "relamping" (replacing a lightbulb). This is at 11-12 hours average runtime per day.
How non-LED traffic lights are different: They use "traffic signal" incandescents with 8,000-hour-life-expectancy. The filaments in those incandescents appear to me to be of a "vibration resistant" sort of design, which compromises efficiency in comparison to shortest-straightest-fattest with-least-supports coiled-coil that tends to be most efficient in most incandescents designed for at least 28 volts and at least 60 watts. Most of these achieve around ~10.2-11 lumens per watt at rated voltage, though mostly around ~8.6-9.3 lumens/watt for 130V ones used at 120V. This is before how roughly 94% of their usage is with red or green colored filters that block around ~66-70% of their light output. At that point, overall luminous efficacy of non-LED traffic lights is maybe 33-38% of
8.6-11 lumens/watt. That means maybe 2.8-4.2 lumens per watt for colored LEDs to compare to. The incandescent systems *probably* have some non-color-filter-related optical losses that systems based on colored LEDs can improve opon.
So, improvement upon pre-LED technology gets a lot easier for traffic lights than for streetlights. Non-LED streetlights tend to mostly be ballpark around 20 times as luminously efficient at converting electricity to final output light as non-LED traffic lights.
Recently , Our gorverment authorities, as part of a national pilot exercise on energy saving, replaced 16 unit of street " high pressure sodium lamps" with LED bulbs. The LED bulbs are said to have electricity bill " 18 % energy saving " properties saving up to one millon dollars on monthly. Subsequent plans to replace 100 K unit of street lamp. The plan is to extend replacement of lamp bulbs with LED to include fluorescent lighting used in the public housing, to a tune of 340K units. This move is said to save another five million yearly on electricity bills. I feel that this a knee jerk reaction to the energy saving properties LED lighting has. It is an abuse of the LED technolgy. What do you thinks ? Can any members commemt ? Thanks for advice and reply.
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My posts are not from hash smoking
SO far LED lighting is crap and very limited in usage applications.
HPS is much more efficient and the bulbs may last longer than LED lighting pushed to the new heights of luminance. The LED hype is just that, HYPE mostly. I have used them in my home and they are not up to snuff yet. They are not that efficient in white. despite the cons the promoters would have you believe. The specs are typically bare units and not encapsulated yet, the white light is not a balance spectrum and their are doubts arising regarding the health of humans under them.
There is a lot of history of new lighting technologies causing disappointments. Sometimes, and especially in many cases with LED replacement lighting, the claims of gain in energy efficiency are overstated or half-truths. Also, the replacement lighting units sometimes don't produce the same quality of light, or the same light distribution pattern, as that produced by what was replaced.
Those in charge of procuring lighting units of a different technology should check out units already installed for customers who are happy with them. Preferably, a few existing units should be retrofitted on a local pilot study basis.
I have seen a lot of stories of replacing HID lighting units with LED ones that sounded to me too good to be true, especially considering the efficiency of the best *feasibly and economically available* LEDs that could have been used in units made before the times when some of these stories came out. One thing: I have not seen much in increase in claims of energy efficiency improvement by going with LED here in the past 4 years, while LED efficiency did increase significantly in that time. This makes me think that the claims "were not quite right" back then, maybe to put it mildly, and I would not count on them being "fully true" now until tested/verified.
Things to watch out for:
Comparison of brand new clean replacement units with aged/dirty existing units
Overstating energy consumption rate of existing units
Overstating light output of replacement units for any or any combination of several reasons, some of them ones of incompetence rather than dishonesty
Overstating benefits of different color or different spectrum of the light from the replacement units
LED life expectancy figures turn out to be optimistic (less likely when the LEDs themselves are by a *big name major established LED manufacturer* that publishes a datasheet, and the customer verifies that the LEDs are reliably not having LED current or relevant temperature (such as heatsinkable surface of the LEDs or adjacent heatsink) pushing or exceeding limits specified in the datasheet for good life expectancy. (Preferably the datasheet states for fading by typically no more than to 70% of "initial" light output at 50,000 hours.) Watch out for how non-contact thermometers read bare metal, and how any thermometer used by a salescritter or used in a manner recommended by a salescritter can read low for what such salescritter is selling.
However, I actually do not like HPS lamps. I like metal halide better for effectiveness of illumination, and I like LED better still when done right and done with honest and verifiable numbers, if the numbers add up to be advantageous.
--
- Don Klipstein (don@misty.com)
Concur on all that but would like to add.
Many of the efficiency specs were issued without ballast circuitry losses
and without encapsulation losses.
Coloured LEDs win hands down over most of other lighting types but not
so-called "white" LEDs and some of the spectrum is missing which is being
blamed for health problems without a properly balanced light for humans.
Sodium bulbs are so far out front for efficiency that LEDS have a long way
to go, yet. LED's also have heat problems and require a lot of heat sinking
or their own inefficiencies burn themselves out.
mike
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