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Lighting Comparison Chart from the Department of Energy

LED Lighting

The light-emitting diode (LED) is one of today's most energy-efficient and rapidly-developing lighting technologies. LEDs last longer, are more durable, and offer better light quality than nearly any other type of lighting available.

Energy Savings

LED is a highly energy efficient lighting technology, and has the potential to fundamentally change the future of lighting in the United States. Residential LEDs—especially ENERGY STAR rated products—use at least 75% less energy, and last 25 times longer than incandescent lighting.

Widespread use of LED lighting has the greatest potential impact on energy savings in the United States. By 2027, widespread use of LEDs could save about 348 TWh (compared to no LED use) of electricity: this is the equivalent annual electrical output of 44 large electric power plants (1000 megawatts each), and a total savings of more than $30 billion at today's electricity prices.

How LEDs are Different

LED lighting is very different from other lighting sources such as incandescent bulbs and CFLs. Key differences include the following:

Light source

LEDs are near-monochromatic light sources. They emit various colors (except white) depending on the materials from which they are made.

Direction

LEDs are directional—much like a flashlight—which makes them ideal for applications such as recessed downlights and task lighting. With other types of lighting, the light must be reflected to the desired direction and more than half of the light may never leave the fixture.

Heat

LEDs emit almost no heat. In comparison, incandescent bulbs release 90% of their energy as heat and CFLs release about 80% of their energy as heat.

Light-emitting diodes emit light in a specific direction, reducing the need for reflectors and diffusers that can trap light. This feature makes LEDs more efficient for many home and industrial uses.

LED Products

LED lighting is currently available in a wide variety of home and industrial products, and the list is growing every year. The rapid development of LED (light-emitting diode) technology leads to more products and improved manufacturing efficiency, which also results in lower prices. Below are some of the most common types of LED products.

Industrial and Commercial Lighting

The high efficiency and mono-directional structure of LEDs makes them ideal for many industrial uses. LEDs have largely replaced incandescent bulbs in traffic signals. They are also increasingly common in street lights, automobiles (interior and exterior), walkways, computer components, and signs and displays.

You can find LEDs in recessed downlights and under-cabinet lighting fixtures for homes.

Kitchen Under-Cabinet Lighting

Because light-emitting diodes provide such strong lighting in one direction, they are ideal for lighting countertops for cooking and reading recipes. The color can appear more cool or blue than is typically desirable in a kitchen, and there can be some excessive shadowing in some fixtures, so it is important to compare products to find the best fixture for your space.

Recessed Downlights

Recessed downlights are commonly used in kitchens, hallways, and bathrooms in homes, and have largely replaced ordinary street lights. DOE estimates there are at least 500 million recessed downlights installed in US homes, and more than 20 million are sold each year. Both compact fluorescent (CFL) and LED technology can decrease downlight wattage by 75% or more.

Portable Desk and Task Lighting

The small size and directionality of LEDs make them well-suited to desk and task lighting. New LED portable lamps appear on the market frequently and performance varies widely. Be sure to evaluate products on an individual basis to check color quality, light output, and energy-efficiency before buying.

Holiday Lights

LED Holiday lights are very popular and easy to find.

Decorative light strings such as Christmas tree lights are among the most popular and most affordable LED consumer products on the market. Not only are the LED bulbs far brighter and less yellow in color than incandescent ones, but they save 90% or more in utility costs, operate at cooler temperatures, and have an operational life span of roughly 20,000 hours (enough to last for 40 holiday seasons). In addition, LED lights do not suddenly "burn out," which makes replacing dead bulbs in a string of lights unnecessary.

Advantages of LED Holiday Lights

LED holiday lights have many advantages over ordinary incandescent lights:

• Running LED holiday lights on one 6-foot tree for 12 hours per day for 40 days can save 90% or more energy when compared to traditional incandescent holiday lights:
  
  

  Type of Light	Electricity Cost *
  Standard C-7 (125 bulbs, 4 watts each)	$27.21
  Mini incandescent lights (300 bulbs, 0.4 watts each)	$6.53
  LED holiday lights (280 bulbs, 0.04 watts each)	$0.61

  *Assumes an electricity price of 11.26 cents per kilowatt hour U.S. Energy Information Administration Average Retail Price of Electricity to Ultimate Customers by End-Use Sector.

• LED holiday lights last longer; they have an operational life span of roughly 20,000 hours, enough to last for 40 holiday seasons
• LED holiday lights are cooler than incandescent bulbs, reducing the risk of fire and personal injury
• LED holiday lights are more durable than incandescent bulbs, with lamps typically made out of solid plastic rather than glass
• Because they use less power, it is safer to connect multiple strings of LED holiday lamps end-to-end without overloading the wall socket.

Lighting Principles and Terms

To choose the best energy-efficient lighting options for your home, you should understand basic lighting principles and terms.

Light Quantity

Illumination

The distribution of light on a horizontal surface. The purpose of all lighting is to produce illumination.

Lumen

A measurement of light emitted by a lamp. As reference, a 100-watt incandescent lamp emits about 1750 lumens.

Footcandle

A measurement of the intensity of illumination. A footcandle is the illumination produced by one lumen distributed over a 1-square-foot area. For most home and office work, 30–50 footcandles of illumination is sufficient. For detailed work, 200 footcandles of illumination or more allows more accuracy and less eyestrain. For simply finding one's way around at night, 5–20 footcandles may be sufficient.

Light Energy Consumption

Efficacy

The ratio of light produced to energy consumed. It's measured as the number of lumens produced divided by the rate of electricity consumption (lumens per watt).

Light Quality

Color temperature

The color of the light source. By convention, yellow-red colors (like the flames of a fire) are considered warm, and blue-green colors (like light from an overcast sky) are considered cool. Color temperature is measured in Kelvin (K) temperature. Confusingly, higher Kelvin temperatures (3600–5500 K) are what we consider cool and lower color temperatures (2700–3000 K) are considered warm. Cool light is preferred for visual tasks because it produces higher contrast than warm light. Warm light is preferred for living spaces because it is more flattering to skin tones and clothing. A color temperature of 2700–3600 K is generally recommended for most indoor general and task lighting applications.

Color rendition

How colors appear when illuminated by a light source. Color rendition is generally considered to be a more important lighting quality than color temperature. Most objects are not a single color, but a combination of many colors. Light sources that are deficient in certain colors may change the apparent color of an object. The Color Rendition Index (CRI) is a 1–100 scale that measures a light source's ability to render colors the same way sunlight does. The top value of the CRI scale (100) is based on illumination by a 100-watt incandescent light bulb. A light source with a CRI of 80 or higher is considered acceptable for most indoor residential applications.

Glare

The excessive brightness from a direct light source that makes it difficult to see what one wishes to see. A bright object in front of a dark background usually will cause glare. Bright lights reflecting off a television or computer screen or even a printed page produces glare. Intense light sources — such as bright incandescent lamps — are likely to produce more direct glare than large fluorescent lamps. However, glare is primarily the result of relative placement of light sources and the objects being viewed.

Lighting Uses

Ambient lighting

Provides general illumination indoors for daily activities, and outdoors for safety and security.

Task lighting

Facilitates particular tasks that require more light than is needed for general illumination, such as under-counter kitchen lights, table lamps, or bathroom mirror lights.

Accent lighting

Draws attention to special features or enhances the aesthetic qualities of an indoor or outdoor environment.

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