Types of Light Sources and Light Bulbs

Accent Lighting

Adds drama to a room by creating visual interest. As part of an interior design scheme, it is used to draw the eye to houseplants, paintings, sculptures and other prized possessions. It can also be used to highlight the texture of a brick or stone wall, window treatments or outdoor landscaping. To be effective, accent lighting requires as least three times as much light on the focal point as the general lighting surrounding it.

I am standing in the store looking at light bulbs; what do I need to look for?

Check the packaging for the following: •Lumens: How bright is the bulb? •Color: Is the light from the bulb a warm 2700K or a cool 4000K? •CRI: Does the bulb render colors beautifully? 80+ is good, 90+ is great! •Dimmable: Can I use the bulb with a dimmer switch? What type of dimmer is compatible?

How is the efficiency of a light bulb measured and rated?

Efficiency (or efficacy) is the light output of the bulb (lumens) divided by its power input (watts), i.e. lumens per watt. The standard household bulb of a few years ago rated for 60 watts generated 800 lumens and had an efficacy of about 13 lumens/watt. Today, an LED bulb rated for 800 lumens would draw about 8 watts, for an efficacy of 100 lumens/watt, making is significantly more efficient!

Reflectorized Incandescent Bulbs

Have a reflective coating inside the bulb that directs the light in one direction rather than all around. Reflector (R) bulbs put approximately double the amount of light (footcandles) on the subject as General Service (A) of same wattage. Parabolic Reflector (PAR) bulbs control light more precisely. They produce about four times the light of General Service (A) and are used in recessed and track lighting. Weatherproof casing makes them suitable for outdoor spot and flood fixtures.

Task Lighting

Helps you perform specific tasks, such as reading, grooming, preparing and cooking food, doing homework, working on hobbies, playing games and balancing your checkbook. It can be provided by recessed and track lighting, pendant lighting and undercabinet lighting, as well as by portable floor and desk lamps.

LUMEN

Lighting Understanding for a More Efficient Nation. Coalition of 40-plus organizations, with a Steering Committee led by the American Lighting Association, the Alliance to Save Energy, and the National Electrical Manufacturers Association.

Are there any harmful materials in LED bulbs?

LED bulbs are electronic products and the materials are similar to what is used for cell phones, TVs and other electronic devices. LED bulbs contain glass, metal and plastics that can - and should - be recycled.

How about temperature conditions - do low or high temperatures affect LEDs?

LEDs, in general, operate well at low temperatures, but check the bulb ratings to see the temperature range for which the bulb was designed. High temperatures can drastically shorten LED bulb life, and household bulbs should not be installed in tightly enclosed fixtures where heat build-up might affect the bulb performance. There are LED bulbs available, however, that are rated and marked for enclosed fixtures.

Efficacy

Lumens per watt

Tungsten-Halogen Incandescent Bulbs

Produce a brighter and whiter light than other incandescent bulbs. They also have a longer life and provide more light per watt than standard incandescent bulbs, making them a more efficient choice. Halogen bulbs are available in two types: line voltage (120 watt) and low voltage (12 volt).

High-Intensity Discharge (HID) Bulbs

Produce light when an arc passes between cathodes in a pressurized tube, causing metallic additives to vaporize. They have long lives and are extremely energy efficient, but - with the exception of metal halides - they do not produce pleasing light colors. In residential settings, HIDs are most often used for outdoor security and area lighting. There are four types of HIDs: Metal Halide High-Pressure Sodium Low-Pressure Sodium Mercury Vapor

Fluorescent Bulbs

Produce light when an electric arc passes between cathodes to excite mercury and other gases producing radiant energy, which is then converted to visible light by a phosphor coating. They use 1/5 to 1/3 as much electricity as incandescents with comparable lumen ratings and last up to 20 times longer.

Incandescent Bulbs

Produce light when an electric current passes through a filament and causes it to glow. Because they are less energy efficient than other light sources, they are best used for task lighting that demands high levels of brightness. The types of incandescent bulbs available include: General Service Reflectorized Tungsten-Halogen Xenon

Light Emitting Diodes (LEDs)

Produce light when voltage is applied to negatively charged semiconductors, causing electrons to combine and create a unit of light (photon). In simpler terms, an LED is a chemical chip embedded in a plastic capsule. Because they are small, several LEDs are sometimes combined to produce a single light bulb. LED lighting in general is more efficient and longer lasting than any other type of light source, and it is being developed for more and more applications within the home.

Ambient (General) Lighting

Provides an area with overall illumination. Also known as general lighting, it radiates a comfortable level of brightness without glare and allows you to see and walk about safely. In some spaces such as laundry rooms, the ambient lighting also serves as the primary source of task lighting.

Xenon Incandescent Bulbs

Rigid-loop, festoon and wedge base bulbs have a white light similar to that of halogen but have a much longer life rating (some up to 20,000 hours, much like fluorescent) and operate at lower temperatures than halogen. These miniature bulbs are popular for strip, under-cabinet and cove lighting applications.

Compact Fluorescent Lamps (CFLs)

Small fluorescent bulbs that can be used in most types of lighting fixtures. The screw-in types can be used to replace incandescent lamps in standard lamp sockets.

Wattage

The amount of electricity consumed by a light source

Footcandles

The amount of light reaching a subject

Lumens

The amount of light that a light source produces

General Service Incandescent Bulbs

The inexpensive, readily available light bulbs that most of us think about when we hear "light bulb." They produce a warm, yellow-white light that is emitted in all directions and are available in either a clear or frosted finish. There are three basic shapes: General (A) Globe (G) Decorative (Flame, teardrop and other shapes)

How long should I expect an LED bulb to last?

The short answer is 10-20 years for home applications where the LED bulb is normally burned for the typical 1-3 hours/day. The rated life of an LED bulb is based upon burning hours, and typically life ratings for LED household bulbs are 10,000 hours or more, with some rating as many as 40- to 50-thousand hours starting in 2017. However, LED bulbs are not likely to fail by simply burning out. It is more likely that they will just gradually get dimmer over time. To claim a rated life of 15,000 hours, for example, Energy Star-qualified bulbs must pass sample tests that require they produce no les than 93.1 percent of their initial light output after they have been burned for 3,000 hours.

T8 Fluorescent Bulbs

With electronic ballasts are commonly used in larger ceiling fixtures. Because of the electronic ballasts, they turn on instantly and do not hum. They are commonly used in commercial projects and are now being widely used in residential applications.