Green Lighting

Glossary of Lighting Terms


All fluorescent light bulbs, including Compact Fluorescent Lights require a ballast to operate. The ballast starts the light bulb and controls it during use. Unlike tubular fluorescent lights, where the ballasts are separate, Compact Fluorescents have the ballast built into the bulb.


The threaded part of the light bulb that inserts into the socket.
Note: The incandescent bulb previously used in most applications has a Medium Base, technically an E26 base. The candelabra bulbs in many chandeliers and in both indoor and outdoor wall mounted decorative lights can have either an E26 Medium Base or a smaller E12 Candelabra base. Please check the base type you need before ordering CFLs.


Compact Fluorescent Light Bulb. Small, usually spiral light bulbs that replace incandescent bulbs and fit in the same sockets. CFLs include an integral self ballast so that no additional external ballast is required. Many Colors, Wattages, CRIs and shapes are available.

CO2 Reduction

The amount of Carbon Dioxide that is saved from being released into the atmosphere over the rated life of the Compact Fluorescent Lamp (CFL) when compared to an equivalent incandescent bulb.

Color Rendering Index (CRI)

Describes numerically how well a light source produces (renders) colors in objects. CRI uses a scale of from 1 to 100 with 100 being the optimum. Most of the newer CFL bulbs produced today have a CRI of 82 which is very good.

Color Temperature

The actual color of the light source itself in Kelvin units. 2700K is a relatively warm light source (like Incandescent), 3500K a bit cooler (like Warm White Fluorescent tubes) while 5500K is “refrigerator” cold (even “whiter” then Cool White Fluorescent tubes).

Color Explanation
Soft White 2700K – Ideal for: Living Rooms, bedrroms, family rooms and recreation rooms.
Bright White 3500K – Ideal for: Kitchen, bathroom, basement and garage.
Cool White 4100K – Ideal for: Office, commercial space and institutions.
Natural Light 5500K – Ideal for: Visual Tasks, reading, sewing and crafting.
Day Light 6500K – Ideal for: Reading and task lighting.


The amount of light, in lumens, emitted by a bulb divided by the power in watts used to operates the bulb. “Lumens per watt”, the efficacy of a bulb is similar in concept to “miles per gallon” for an automobile. [Efficiency refers to how much of the light source lumens emerges from the light fixture. Efficacy is the term applicable to light sources themselves]

Energy Savings

This measures the amount of energy the CFL lamp will save when compared to an incandescent of equivalent lumens.

Initial Lumens

The amount of light emitted by a light bulb in its first 100 hrs of use.


The amount of light emitted by a light bulb.

Mean Lumens

The amount of light emitted by a bulb at its mean lifetime or 40% of rated life.

Motion Sensors

Automatically turn lights on when they are needed (read: when motion is detected) and turn them off a short while later.


Electrical potential. Most domestic and commercial voltage supply is 120 volts. Incandescent and CFL bulbs operate when connected directly to a 120 volt supply. The higher the voltage, the greater the potential to pass along current through the circuit. (240 volts available for some heavy appliances and 277 volts often used or large installations such as Big Box stores).


The unit of power consumed to make the light bulb operate. The wattage utilized per month is the basis for the Utility power bill. Wattage is theoretically the product of Volts times Amps (Current). Light Bulbs are described by their wattage, Such as 13 W CFL, or 60 W Incandescent etc.

There are two ways of spreading light: to be the candle or the mirror that reflects it.

Edith Wharton