LEDs are often described in marketing materials as "cool" lighting, and in fact LEDs are cooler than halogen or incandescent. On the other hand, LEDs do in fact generate heat! Consequently, luminaire designers must be conscious of potential heat dissipation challenges and how those challenges may affect LED performance, longevity, and even lamp safety.
Without good heat sinking, the junction temperature of the LED rises, and this causes the LED characteristics to change. Heat sinks seek to transfer heat from the LED to the air, which as a more fluid medium, may naturally move the heat away from the LED, helping to keep the junction temperature lower.
High temperatures can both shorten the life and impact the brightness of LEDs. Studies have shown that decreasing the operating temperature by 10 degrees can double the lifetime of LEDs. As a result, virtually all luminaries require some type of heat-sink or other thermal management technology.
With the Palindrome RBW has worked with an advanced computer modeling software to design a Cast Aluminum heat sink to reduce the operating temperature of the LED boards. Shown below are 3D models and thermal images of the 8.5W LED board operating in our lab.
Although many LED lights offer a dimmable range, (such as 100% to 0%) there is a difference between the measured value of light and the perceived value of light.
For instance, an LED light that is dimmed to a measured value of 10% will be perceived by the human eye as a value of 31%. This difference is important to keep in mind when buying and specifying LED lights and dimmers.
To continue last week's topic of dimming, today we will discuss the difference between Leading Edge Dimming and Trailing Edge Dimming.
Leading Edge Dimming (TRIAC dimming) utilizes a current that is turned off as the AC waveform begins, right after it crosses zero. Leading Edge Dimming is typically used with incandescent bulbs, and produces a rush of voltage every half cycle, resulting in a rush of current to the light source.
Trailing Edge Dimming (electronic dimming) utilizes a current that is turned off as the AC waveform ends, right before it crosses zero. This type of dimming is typically used with electronic drivers, and does not result in a rush of voltage (and in turn, a rush of current) to the light source.
There are two main types of dimming that can be used with LED light sources. These are TRIAC (Triode for Alternating Current) dimming and 0-10 Volt dimming.
TRIAC dimming relies on adjustable timing of power at the start of each AC half cycle, which alters the voltage waveform to dim a light source. TRIAC dimming is almost instantaneous and wastes very little power.
0-10 V dimming utilizes a DC voltage that varies from 0 V to 10 V to dim a light source. 0-10 V dimming typically runs at a low current with little voltage drop.
Just like an incandescent bulb, an LED light gives off heat when it is powered. Because of this, LEDs require heat sinks to help dissipate the heat that they generate.
By examining thermal images of our fixtures (like the one of Monocle above), we can assess how well the heat is dissipated throughout the fixture to ensure the longevity of our parts.
There are four different LEED Certification levels- Certified, Silver, Gold, and Platinum. LED lighting can play a huge role in bringing a building to LEED standards.
There are three categories of LEED Certification that can be effected by the use of LED lighting. These categories are:
Innovation and Design Process- promotes the sourcing of innovative products
By understanding the guidelines behind LEED Certification, architects and designers can strive for greener and more efficient buildings.
Although the Watt is a very common unit of measurement for light sources, it does not actually measure how much light a source gives off.
Watts measure how much energy is required to power a light source, whereas Lumens measure the ammount of light emitted by a light source. The more you know!
CRI, or Color Rendering Index, is a measure of how accurately a light source is able to reveal the intrinsic colors of what it is illuminating. Established in the 1960s, CRI is an extremely important measurement for assessing the color performance of a light source.
CRI testing is achieved by comparing eight color chips (R1 to R8) to a reference source of the same color temperature.
The CRI scale runs from 0 to 100, with a rating of 80 or above typically being most desirable for indoor lighting applications.
Longevity means less maintenance. Instead of monthly bulb replacements, Mori can run for over 30,000 hours, potentially a decade, before requiring LED chip replacement (and should need arise, we've got all our RBW fixtures covered with replacement parts available at our web store).
Come check out RBW's booth at BDNY this weekend! Say hello at Booth 522.
The event runs from November 9th to November 10th.
Untill then, enjoy this candid sneak preview.