Color Temperature is standardly expressed in kelvins (K). Standard Color temperatures for commercial settings can range from 2000K (Warm) to 6500K (Ultra White). Warmer colors, or lower color temperatures colors are often used in public areas to promote an ambience of relaxation, while cooler colors, or higher color temperatures are used to help visibility and concentration.
- Orange/Yellow (<1000K-1400K)
- Warm (1500K-2500K)
- Warm White (2600K-3200K)
- Neutral White (3500K-3900K)
- Cool White (4000K-4900K)
- Daylight (5000K-5900K)
- Ultra-White (6000K-7000K)
- Blue White (7500K-9000K)
- Blue (9500K+)
“The effect of an illuminant on the color appearance of objects by conscious or unconscious comparison with their color appearance under a reference illuminant.” (International Commission on Illumination (CIE) 17.4, International Lighting Vocabulary)
A lamp/bulb’s Color Rendering Index (CRI), or CIE Ra value, is a measurement of light’s ability to reveal colors of various objects in comparison with a natural/ideal light source. A higher or lower CRI changes the way colors of various objects are illuminated. The lower the CRI, the duller the colors will appear, and the higher the CRI, the more ‘true’ colors will appear. On the CRI scale (0-100), we recommend lighting that is 80 CRI or higher to achieve more realistic colors in your space.
How to Measure Lightbulbs
Lamp Shapes are designated a letter and a number (e.g. A21, T8, etc.) The letter denotes the shape of the bulb and the number indicates the bulb’s diameter in eighths of an inch (1/8”).
To see the list of shapes, click here.
Baffle: An opaque or translucent element of a light fixture blocks the direct light, either to absorb or impede unwanted light, or to reflect or re-direct light.
Ballast: A device used with a fluorescent or HID lamp to create the necessary circuit conditions (voltage, current, and wave form) for starting and operating the lamp.
Color: (Correlated Color Temperature?): The perceived color of the light measures by the absolute temperature of a black body radiator with the same apparent color as the light source. Warm hues (orange and yellow tinted lights) have lower CCT values, and cool hues (blues and bright whites) have higher CCT values.
CRI (Color Rending Index): a scale from 1-100 (1 being the worst, 100 the best) that measures how well an artificial light source shows the full color spectrum of the objects it illuminates compared to natural light. A lower score indicate that colors look dull and muddy, and scores of 80 CRI or above show colors well.
Cove Lighting: A type of lighting built into ledges and recesses in a ceiling or high on the walls. It directs light up towards the ceiling and down adjacent walls.
Direct Lighting: Lighting that distributes 90 to 100 percent of the emitted light on the work surface to be illuminated. The term usually refers to light emitted downward.
Direct-indirect Lighting: Lighting uses some direct light and also indirect reflection, emitting light both down at the workspace and up to the ceiling.
FL (Fluorescent) Lamp: A type of gas-discharge lamp. Within the lamp’s glass tub, electricity excites mercury vapor that emits ultra-violet light and causes the lamp’s fluorescent coating (phosphor) to glow, producing the light. Fluorescent lamps come in many different shapes:
- Linear Fluorescent (LFL): A long, thin tube available in many sizes.
- Compact Fluorescent (CFL): In these lamps, the glass tubes are folded into many different shapes to save space. These include spiral lamps, the standard lamps shaped like traditional light bulbs, globe lamps that are very round, triple tube lamps that pack lots of tubing into a small area, flood lamps shaped to fit into a recessed space with diffused light, and candle lamps that mimic the shape of a flame.
Footcandle (fc): A unit of luminescence. One footcandle is one lumen per square foot (lm/ft2)
High Bay: Interior lighting where the ceiling is more than 25 feet off the floor, designed to provide well-distributed, uniform light for open areas.
High Intensity Discharge Lamps (HID) : A type of electrical gas-discharge lamp that produces light using an electrical arc between tungsten electrodes inside a clear tube that is filled with both gas and metal salts. The gas helps the spark light, and once the electricity starts arcing between the electrodes, the metal salts heat up and form a plasma that increases the intensity of the light produced by the electrical arc. HID lamps include groups of lamps known as high-pressure mercury, metal halide, and high-pressure sodium.
Indirect Lighting: Lighting involving luminaires that distribute 90-100% of the emitted light upward, reflecting light off of the walls and ceiling to light the room to diffuse light throughout the room.
Lamp Shape: Each different lamp shape is designated with either a letter or name, such as G (for globes) and R (for reflectors). Then, the lamp size is indicated with a number, with lower numbers indicating smaller sizes. So, a G9 and a G30 both have the same shape—a globe—but the G9 is much smaller than the G30.
LED: Light Emitting Diode. A device that generates light by the recombination of electrons in the junction between two different semiconductor materials. The light emitted may be ultraviolet, visible, or infrared. LEDs are the foundation of LED lamps.
Life (Lamp Life): This will describe how this is calculated. The statistically determined estimate of the total operating time at which, under normal operating conditions, 50 percent of any large group of initially installed lamps is expected to still be operating.
Low Bay: Interior lighting where the roof trusses or ceiling height is less than 25 feet.
Lumens: an SI unit of luminous flux (luminous intensity), used to measure of the total quantity of visible light emitted by a source.
Luminaire: A complete lighting unit consisting of a lamp(s) and ballast(s) (when applicable) together with the parts designed to distribute the light, to position and protect the lamps, and to connect the lamps to the power supply.
Metal Halide (MH): A high intensity discharge lamp(HID) in which the major portion of the light is produced by radiation of metal halides and their products of dissociation—possibly in combination with metallic vapors such as mercury. Includes clear and phosphor-coated lamps.
Refractor: A device used to redirect the flow of light from a source by bending the light’s direction. Refraction occurs when light enters a material that slows down the rate the light can travel, so the light wave bends.
Task Lighting: Lighting directed to a specific surface or area that provides illumination for visual tasks.
Troffer: A long, recessed lighting unit usually installed with the opening flush with the ceiling.
Voltage: Volts measure the pressure, or force, of electricity. It measures the electrical potential energy per unit charge, or the potential difference in charge between two points in an electrical field.
Watts/Wattage: Watts measures the amount of power required the work electricity does per second, or the power output. Watts are found by multiplying the amperage (the amount of electricity) by the volts (the pressure of the electricity).