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A Few Thoughts About Lighting

Paul Kando

Up to 25% of the average home energy budget goes for lighting. The electricity used over the lifetime of a single conventional incandescent bulb costs 5 to 10 times the original purchase price of the bulb itself. Compact fluorescent bulbs (CFLs) are miniature versions of full-sized fluorescent tubes screwed into standard lamp sockets. And, unlike the fluorescent lighting we associate with factories and schools, CFLs give off light that looks similar to common incandescent lighting.

LED Bulb
LED Bulb
photo credit: Philips Lighting

Light Emitting Diodes (LED) are small, very efficient solid light sources. When first developed, they were limited to applications such as instrument panels, electronics, pen lights and, more recently, strings of indoor and outdoor Christmas lights, where small single bulbs could be used.

To make LEDs more useful, manufacturers have developed “clusters” of these small bulbs. The first clustered bulbs were used for such battery powered products as flashlights and headlamps, where the high efficiency of the LEDs could significantly expand battery life.

Unlike conventional incandescent bulbs and CFLs, which spread light in all directions, LEDs emit light directionally. This is an advantage with flashlights, recessed, or under-cabinet lighting, but a disadvantage for table lamps or room lighting. To overcome this directional limitation new LED bulbs include diffuser lenses and reflectors that disperse the light more like an incandescent bulb. Today’s LED bulbs use as many as 180 bulbs per cluster, encased in diffuser lenses which spread the light. They are available with standard bases that fit common household light fixtures.

LEDs are the next generation in home lighting, with many new bulb styles now available. However the high cost of producing LEDs has been a roadblock to their widespread use, until researchers at Purdue University came up with a replacement for the expensive original sapphire-based technology to produce LEDs. The latest generation of LEDs uses these less expensive silicon wafers.

Still more expensive to buy than incandescents or CFLs, LEDs exceed both in value because: (1) They last longer – up to 10 times as long as CFLs, and far longer than typical incandescents. (2) LEDs are more durable. Having no filament to break, they are not damaged under circumstances when a regular incandescent bulb would be broken or fail due to jarring and bumping. This makes LEDs ideal for motor vehicles and other transportation applications. (3) LED bulbs are cool – there is no heat build-up. LEDs produce 3.4 Btu's of heat per hour, compared to 85 or more for incandescent bulbs, which contribute to heat build-up in a room – a very expensive way to heat. LEDs prevent heat build-up, thereby helping to reduce summer air conditioning costs. (4) Unlike CFLs, LEDs are mercury-free. (5) LEDs are more efficient and reduce your electric bill – they produce the same amount of light using 1/3rd the electricity of a CFL and 1/30th the electricity of a conventional incandescent bulb. (6) LED bulbs save money on replacement costs as well, since LED bulbs last up to 50,000 hours, compared to 10,000 hours for a CFL and only 1,200 hours for an incandescent bulb. (7) LEDs also extend battery life 10 to 15 times over incandescent bulbs, in applications like emergency lighting, flashlights and or off-grid solar systems.

In terms of light output here is how LEDs compare to other bulbs:

Light Output

There are many different models and styles of LED bulbs, available in a number of colors as well as both 'cool' white light (for task lighting), and 'warm' light (for accent or small area lighting). They are available with several types of 'pin' sockets or standard "screw” (Edison) bases. Choose between standard and dimmable bulbs that will work with standard dimmer switches. But choose high quality bulbs or they will die prematurely. Cheap bulbs are “inexpensive” only because they use a low-quality chip which fails easily. It is a good idea to look for certifications, such as FCC, Energy Star and UL.

As manufacturing technology improves so does reliability. And, following the pattern of other electronic devices, LED prices have been dropping. Just as distributed solar panels are the energy source of the future, LEDs will be the mainstay of lighting. The two technologies are well matched to each other and to a world where energy efficiency, without compromising comfort and reliability, is fast becoming the key to success. Furthermore: every 7 watt LED, on 3 hours per day, consumes about 8 kWh of electricity, costing $1.20 per year, compared to every light-equivalent 60 watt incandescent that consumes 66 kWh costing $10 annually.

What’s not to like?