Light emitting diodes (LEDs), first out in the mid-1960s, are semi-conductor devices that give off illumination through an electric current. Basically, LEDs are tiny light bulbs that fit into an electrical circuit; they don’t have a filament, don’t get very hot and last as long as a standard transistor.
The light emitted comes from the movement of electrons in the semiconductor material. You can see LEDs used as “pilot” lights in electronic appliances, indicating whether the circuit is closed or not; you can see them used for outdoor lighting, signage and some indoor lighting.
In contrast to incandescent or fluorescent lighting devices, LEDs are long lasting, sometimes 50,000–100,000 hours when properly installed; very robust and don’t break easily; environmentally friendly; and energy-efficient. They do not emit much heat (heat is just wasted energy), but the electrical power they use goes directly to generating light, which cuts down on electricity demands. In addition, LEDs have a low power requirement, though they do use some.
Commercial and residential applications
LEDs are used differently in commercial building than in residential construction. Some commercial applications include:
- Cove lighting to highlight a display
- Counters in retail establishments for display-shelf lighting
- Message centers to get a message across faster and better than standard static displays
- LCD-panel backlighting (white LEDs are used on flat-panel computer displays)
- Accent lighting (colors, or where light splashes out from the object)
- Indoor and outdoor signs
Some residential applications include home-entertainment remote controls that use infrared LEDs (IREDs) to transmit data to the main unit; interior accent lighting where a built-in microprocessor can mix red, green and blue LEDs that produce extensive color ranges to bring dramatic lighting effects to white walls; and outside in the garden, on walkways and for decorative fixtures.
When a new building contract is awarded, it is a good time to explore using LEDs for R30-type lighting because an LED R30 can last longer than incandescent lighting and use fewer watts for more light.
Contractors/installers should become familiar with LED features and requirements. Since the contractors probably won’t be the drivers of LED usage, they should be able to install LEDs as part of their service offerings.
Often, a general or electrical contractor will buy a fully integrated LED system, which could include the power supply, ballast, the LED-containing fixture, proper heat sinking and optics.
If installed outdoors, LEDs must be placed in a weatherproof electrical enclosure, and damp location drivers should be used in signs or raceways where some moisture is expected. Also, know what the heat output of the LEDs will be during operation. You will need ample heat dissipation in the installation by mounting to metal or allowing for some ventilation.
Jeff Bisberg of AlbEO Technologies Inc., Boulder, Colo., gave examples of what to watch for during an installation. “Many of the LED systems on the market today are 12-volt DC. DC power is not readily available in most commercial and residential buildings, so the installer should make provisions to locate a power supply.
“Newer products, including AlbEO’s, run off low-voltage AC, which use transformers instead of power supplies, are more compact and easier to install. Of course, the transformer or the power supply needs to [be] sized properly to handle the load of the lighting system.”
When LED fixtures are used, they emit less heat and, therefore, have lower power costs. Once installed in a building, they can also contribute to lower maintenance costs, because long-lasting LEDs rarely need replacement, especially when compared to fluorescent or incandescent lamps.
The lighting quality is comparable to that of cool white compact fluorescent lamps, without the flicker, and the light is very directional in small arrays. LED strip lights can be installed under counters, in hallways and on staircases. When it comes to room lighting, concentrated arrays can be used. Waterproof, outdoor fixtures are also available.
LEDs offer a new option for customers looking for a specific solution, such as lighting in confined spaces or in an application where color, brightness and long life are critical. Many of today’s applications such as exit signs, traffic lights and indicator lights use colored LEDs.
Use of LEDs in architectural applications is becoming more prevalent, such as in the photo on page 110. White LEDs are widely used in some niche applications, such as outdoor lighting and in some small, confined indoor spaces. White LEDs can be very useful in these applications, and when mass produced, should become part of the general lighting mass market.
Specifiers can choose LEDs as a complete system solution, such as in a light fixture. Contractors can often buy and install LED products directly into the application.
White LEDs present a problem because product choices are slim, and they offer poor color rendering and a high color temperature. However, progress is continuing rapidly. As improvements are made to the technology in the lab, we can expect these problems to be corrected.
An example of the growth direction of this market comes from Philips Lighting and Hewlett-Packard. The companies have launched the joint venture LumiLEDs with the goal of rapidly developing LED technology. Many other manufacturers are also exploring this emerging technology. When looking at the architectural market, some products are available now, although it may take a while before fixture manufacturers begin to roll out a large selection of products that take advantage of this light source for general illumination.
A fully integrated LED system includes the light source, driver, heat sinks, connectors and optics, and it’s important not to overload the driver. LED drivers are rated for a maximum load. Check the environmental rating of the driver and whether it is rated for use within the particular LED system. LEDs should also have short- circuit protection, be designed for the given application, and be able to handle temperature extremes for optimal performance.
Currently, there are no performance standards for white LEDs, which causes much confusion and has been a definite barrier to the usage applications. Without performance standards, one must question maintainability—will the manufacturer keep supporting the systems with spare parts or will entire systems need to be replaced?
When looking to standardize performance of a product, there needs to be a consistency in the methods of measurement, and the LEDs’ lighting performance is measured differently than other conventional lighting systems.
This “method” needs to be a consistent and proven way of measuring an LED’s performance because traditional measurement methods simply do not apply. For example, LED lamp life is based on the useful light output, not on the mortality of the lamp.
Standards are important so that contractors can sort fact from sales claims. As LEDs are developed and marketed, contractors will be able to assess and compare product performance based on common specs. Until then, contractors should evaluate products carefully and assess and compare those with familiar lighting specs, such as ease of installation and use, dimmability, etc.
Because there are no standards set, companies have test labs that can verify meeting measurement requirements and against some safety standards, but don’t necessarily confirm reliability. The contractors can evaluate manufacturers and then decide on one or two vendors to use when appropriate.
The Light Congress Symposium from March 2006 considered LEDs something to look at for the “medium term” (rather than near term) as a more efficient and environmental light source. It’s clear that we are seeing the beginning of a new technology, and it is in the hands of contractors to make their move.
Contractors should learn about and evaluate LEDs, estimate if there will be any hassles or possible callbacks on the job, and see if their profits will be eroded. They should monitor the LED growth potential and realize that they may be called on to install these lights in residential and commercial buildings. EC
MICHELSON, president of Jackson, Calif.-based Business Communication Services and publisher of the BCS Reports, is an expert in TIA/EIA performance standards. Contact her at www.bcsreports.com or firstname.lastname@example.org.