This was a great post from the MIT Technology Review about things to think about when choosing new solid state lamps by Martin LaMonica. The link to the original article is here.
After years of work, LED lighting company have finally achieved their goal of producing a good replacement for the common 60-watt incandescent bulb.
Cree earlier this week released a bulb that mimics the light and shape of the conventional incandescent with aggressive pricing, ranging from just under $10 for a 40-watt equivalent to just under $14 for a 60-watt equivalent. Cree Introduces an LED Bulb Edison Would Love. But Cree is joining many other LED lighting companies targeting consumers. With inefficient traditional incandescent bulbs being phased in many countries, there is a lot of competition.
For the consumer, the main benefits of LED fixtures are clear: they’re energy efficient, can last for more than 20 years and, in many cases, give off good light. The prices have gone down steadily as well as the LED components have dropped in price and lighting companies introduce better designs. We’re now at the point where a number of companies are producing all-purpose LED bulbs with a full range of brightness. Now the question is: how do you distinguish between them? Here are some things to consider.
Qualities of light: Consumers are accustomed to measuring brightness in terms of wattage, but that’s fading away. In the last few months, lighting manufacturers have produced LED lamps that give off about 1,600 lumens, or the same as a 100-watt incandescent. (See, Bright LED Bulbs Arrive at Last.) Because these are new, 100-watt equivalent bulbs will be the most expensive, while the less-bright lamps have already gone down in price considerably over the past three years. (See, LED Lighting Riding the Price-Performance Curve.)
The next question is color, either a cooler white light at 3,000 Kelvin or a warmer, yellow light at 2,700 Kelvin, which is more like an incandescent. One feature of LEDs is that the light can be adjusted to the full spectrum of colors, which opens up some new possibilities. Philips is selling a lighting kit of four bulbs, controllable through a smart phone, where people can choose the color of light from a full palette. (See, Apple Sells Philips’ Color-Shifting Wireless Lights.) I became introduced to cooler, white light when I installed my first LED lamps. I found I prefer the white light during the day, so I use those in my office, rather than the warmer-color bulbs.
Less well known is color quality. In my experience, one is quickly spoiled by higher-quality light. I recently received a Switch LED, which has a color rendering index (CRI), a measure of light quality, of over 80. It’s perfectly acceptable. But I decided I’d rather have the Philips L-Prize bulb, which has a CRI of 93, in a spot by the front door where the light is on more often. Familiarity counts for a lot, too. The new Cree bulb has a CRI of over 80 but its filament tower, where a series of LEDs give off light at the center of the bulb, gives off an even light that resembles the glow of an incandescent filament
Function: Some consumer LED lamps have a shape only an engineer could love. To wick away heat from the LEDs themselves—the pinhole-size semiconductors that produce light—bulbs need to have heat sinks. Many have metal fins on the bottom half of the bulbs, which can make for an odd-looking light. That’s something to consider in certain fixtures where it could be obvious.
LEDs excel at giving off light in one direction, which makes them a very good choice for overhead or spot lights. Some older LED bulbs come in what’s called a “snow cone shape” and only give off light from the top. But now, there are designs for omni-directional light, meaning they can be used for table lamps, for instance. The snow cones didn’t work next to my bathroom mirror because the light was uneven, but the omni-directional LED I bought from GE works fine. Whether a light is dimmable is key feature for many people, and many LED bulbs say they are compatible with most dimmers.
One of the biggest advantages of LEDs is the long life they promise. Some are rated at 25,000 hours, which could be 25 years depending on how much they’re used. If there’s a place that’s tough to reach and you want to avoid replacing the bulb, LED is certainly a better choice than traditional incandescents or halogens, which burn out faster.
The Switch bulb has an advanced cooling system that promises long life and opens it up to new uses. Liquid silicone circulates around the LED light sources near the surface of the bulb and to a large metal heat sink at the base. Because it runs cooler, it can be used in overhead recessed cans, whereas many others can’t, a representative from the online store EarthLED told me.
LEDs are also great for places where you cycle the light on and off quickly because they provide full light right away. Compact fluorescent bulbs take a few minutes to warm up and burn out if you turn them on and off quickly within less than five minutes or so.
Price: Because they use less energy, LEDs will save money over incandescents, halogens, and, because they last longer, than compact florescent bulbs, too. The new Lighting Facts label now used on consumer lighting gives a lifetime energy savings estimate, which can be over $100.
The Philips L-Prize bulb, which costs $50 after a $10 rebate, may be the most expensive LED bulb available now. Despite its price, it gets favorable reviews, which suggests people are willing to pay more for a high-quality, durable and efficient product. At the same time, LEDs still greatly lag halogen and CFL adoption.
The LED industry thinks that $10 is the price that will get people to give this new technology a try and lead to mass adoption. Because of the limits to LED semiconductor improvements, the prices for LED bulbs in the 60-watt brightness category are expected to level off at about $5. That’s still more expensive than the alternatives so consumers will need to consider where LEDs make most sense, rather than just the purchase price.