Everyone is talking about LEDs for outdoor lighting applications, from architect cabinets to environmental planners. But what are the facts?
LEDs bring several advantages to the lighting industry, including high efficiency and durability, and, with superior life over other lamp sources, their required maintenance is greatly reduced. This translates into energy savings, maintenance savings and an overall reduction in cost of ownership over the product's lifetime. Those are the facts. An LED luminaire, if operational eight hours per day, will easily last 18 years without needing to be replaced, will use less electricity, and will require considerably less maintenance work over it's lifespan.
How to think about LED's.
Lumen output is only part of the story and can be misleading. LEDs are not yet as efficient as other lamps sources in terms of lumen per watt but the advantage they have over standard sources is light control. Since the LED light source is so small, it is easier to control the light beam and thusly, possible to use the light more efficiently. By controlling where the light is thrown, less power is necessary to achieve the same light levels in a required area.
The truth is, to fully evaluate an LED product one needs to review the overall system efficiency, optical control, thermal management of the LEDs, and know at what point in time the fixture will reach 30 percent lumen depreciation. Products with good optical efficiency and thermal management will be able to deliver more lumens, on average, than traditional HID products.
Challenges. It's always about the heat, isn't it?
LED fixtures must be designed with junction temperature thermal management as a key component and use the correct LEDs. These products will then be robust enough to operate in most ambient temperature applications. Unlike fluorescent sources, cold temperatures do not impact the performance of LEDs. Furthermore, the extruded aluminum heat-sinks are manufactured using 77% post-industrial recycled material.
The U.S. Department of Energy advises: "Heat management and an awareness of the operating environment are critical considerations to the design and application of LED luminaires for general illumination. Successful products will use superior heat sink designs to dissipate heat, and minimize junction temperature. Keeping the junction temperature as low as possible and within manufacturer specifications is necessary in order to maximize the performance potential of LEDs."
The conclusion speaks for itself. And the planet thanks us in advance.
One of the most common question threads regarding LEDs are their real environmental impact. How much energy can be saved with solid-state lighting? How much will these energy savings reduce CO2 emissions?
Finding the answers to these questions is not easy and the math involved is rather strenuous. So, in order to make it simple, we've done the research and the math for you.
Here are the main points. We'll use statistics from the United States Department of Energy.
A little over one-third of all primary energy is used for generation of electricity, and a little over one-fifth of all electricity is used for lighting. Hence, around one-fifteenth of all energy is used for lighting in the United States alone. Doubling the average luminous efficacy of white lighting through the use of solid-state lighting would potentially:
· Decrease by 50% the global amount of electricity used for lighting.
· Decrease by 10% the total global consumption of electricity (projected to be about 1.8 TW-hr/year, or $120B/year, by the year 2025).
· Free over 250 GW of electric generating capacity for other uses, saving about $100B in construction costs.
· Reduce projected 2025 global carbon emissions by about 300 Mtons/year.
We truly hope that this article brightened up some hazy areas in the LED field. It's a new area and we understand that solid scientific information is difficult to come by. Without doubt, more articles about this exciting field will follow in our next newsletters.
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