HappyLite Natural Lighting Products

About Light: Glossary of Lighting Terms

Apparent Color Temperature: Used to describe the degree of "whiteness" for fluorescent and high intensity discharge lamps.

Average Rated Life: The median time it takes for a lamp to burn out. An ordinary 60 watt bulb can be expected, on the average to burn for 1,000 hours. Based upon continuous testing lamps in laboratories, the 1,000 hour rating is the point in time when 50% of the test samples have burned out and 50% are still burning.

Ballast: Electronic device that converts electrical current to the right quantity of voltage required to start the lamp safely and efficiently.

Magnetic: Least expensive option but are heavier than electronic ballasts, require a few seconds to light and often produce a low hum.

Electronic: Usually lightweight, allow the lamp to start instantly, and consume significantly less energy. Remember, you replace fluorescent lamps for the same reason you change the oil in your car (you don't want to damage the engine). A ballast can cost 11-14 times that of a fluorescent lamp, not including labor. Do not run your fluorescent lamps to the point that they damage your ballast. If a lamp is left in operation beyond the recommended lamp period, the ballast will heat up and destroy the power factor capacitor which changes all the ratings of the ballast. It will no longer operate at the designed voltage/amperage, and wattage. The ballast is damaged.

Beam Angle: Indicates the spread of the beam of light. The smaller the number, the tighter and more intense the beam. A typical 50 watt PAR30 bulb has a beam spread of 8 to 60 degrees.

CRI: Color Rendering Index (CRI) is a term used to describe the extent to which an artificial light source is able to render the "true" color of objects as seen by natural outdoor sunlight which has a CRI of 100. No artificial light source has a CRI of 100. The closer the CRI of a lamp is to 100, the more "true" it renders colors. Generally, a lower CRI indicates that some colors may appear unnatural when illuminated by a lamp.

Color Temperature: Refers to the way color groups are perceived - the psychological impact of lighting. Color temperature is a measure of the visual "whiteness" of a source and is expressed in degrees K. (Kelvin). Color temperature is how cool or warm the light source appears. Red/orange/yellow colors and light sources from this side of the spectrum are described as warm, with a low color temperature (incandescent). Colors and light sources toward the blue end with a high color temperature are referred to as cool (natural daylight).

Efficacy: The ratio of light output (lumens) to input power (watts), expressed in lumens per watt. Used in measuring the amount of light given off by a light source. The higher the lumen efficacy, the more efficient the source is at producing light.

Energy: The electric power input, measured in kilowatt-hours (kwh). Footcandle: A measurement of the quantity of light falling onto a surface or subject. One footcandle is equal to one lumen per square foot. One footcandle equals 10 lux.

Incandescent Lamp: A light source which generates light utilizing a thin filament wire (usually of tungsten) heated to white heat by an electric current passing through it.

Kelvin: A measure of how yellow, blue or white the light from a bulb will look to the human eye. Lower kelvin rated bulbs will appear more yellowish, while higher kelvin bulbs appear to be bluer. A bulb with a kelvin rating of between 5000 to 6500 is comparable to mid-day sun.

Light: Radiant energy which can be seen or sensed by the human eye. Visible light is measured in lumens.

Lumens: A lumen is a measure of the amount of light produced by a lamp, the light coming out of the lamp. A lamp's light output rating expresses the total amount of light emitted in all directions per unit time. Ratings of initial light output provided by manufacturers express the total light output after 100 hours of operation.

Lumen Maintenance: A measure of how a lamp maintains its light output over time. It may be expressed as a graph of light output vs. time or numerically. Lux: The ratio of lumens to surface. Measures the light that actually reaches the target. Lux varies depending upon how far away the target is from the light source and other environmental factors such as wall color, reflectors, etc.

Nanometer: A unit of wavelength equal to 10-9 meter.

Phosphor: An inorganic chemical compound processed into a powder and deposited on the inner glass surface of fluorescent tubes and some mercury and metal halide lamp bulbs. Phosphors are designed to absorb short wavelength ultraviolet radiation and to transform and emit it as visible light.

Parabolic Aluminized Reflector (PAR): A bulb that emits light in only one direction. These lamps control light more precisely. They produce about four times the light of standard incandescence and are used in recessed and track lighting. 30 indicates bulb diameter in eighths of an inch. A PAR30 is 3 3/4 inches (30 eights) across the widest point.

Reflector Lamp: An incandescent, compact fluorescent or HID lamp with a built-in reflecting surface. Incandescent and HID versions are made from a single piece of blow-molded soft or hard glass. CFL versions may be one piece or may be designed so that the inner lamp can be replaced.

Ultraviolet (UV) Radiation: Radiant energy in the range of about 100-380 nanometers (nm). The international Commission on Illumination (CIE) defines UV-A (315-400 NM); UV-B (280-315 nm) and UV-C (100-280).

Verilux: Latin, for true light.

Voltage: A measurement of the electromotive force in an electrical circuit or device expressed in volts. Voltage can be thought of as being analogous to the pressure in a water line.

Watt: The amount of electricity consumed by a lamp. Lamps are rated in watts to indicate their power consumption. Power consumed over time equals the electrical energy used.

More Information:

SAD (Seasonal Affective Disorder)

According to the National Institute for Mental Health, approximately ten percent of Americans currently suffer from SAD and related disorders.

SAD is a disorder characterized by drastic mood swings and depression that occur during the winter months.

SAD sufferers have the following symptoms that occur during the fall/winter months and diminish in the spring:

• Depression Feeling "out of sorts"
• Irritability
• Increased appetite
• Weight gain
• Excessive sleeping
• Decreased energy & interest
• Inability to concentrate

In 1980, Dr. Alfred Lewy discovered that bright light blocks the release of melatonin and helps relieve seasonal depression. Light therapy is the most common treatment and usually involves sitting in front of a light box for approximately thirty minutes each day. It is suggested that the brightness of the light be 10,000 lux.

More info from:

National Organization for SAD
Seasonal Studies Program
9000 Rockville Pike
Bethesda, MD 20892

National Institute of Mental Health
P.O. Box 40190
Washington, DC 20016

Disclaimer: SunriseWD makes no medical claims. Consult a physician before starting any light therapy.