subject: Lighting For Your Home 101 [print this page] The average American household has 28 light sockets, and about 10-20 percent of your electricity bill is from lighting.
Americans can save money and protect the environment by installing ENERGY STAR qualified lighting.
The easiest way to start saving energy is to change out the light bulbs in your current fixtures.
A common misconception is - I have the new bulbs in my closet and I'll replace them as they burn out. While it goes against the way we were raised to stop using something before it's used up this is an area where it really makes more sense. Why pay more for the electricity to power your old bulbs when you can start saving today? If you have the light bulbs, use them!
When looking at indoor lighting for energy efficiency, homeowners should consider:
-Using Cols (compact fluorescent bulbs), Cold Cathode, or LED (light emitting diodes) rather than incandescent bulbs in light fixtures
-Using CFLs Cold Cathode, or LED in portable lighting fixtures that are operated
for more than 2 hours per day
-Using ENERGY STAR-labeled lighting fixtures
-Using occupancy sensors to turn lights on and off as needed
-Painting walls and ceilings white to maximize natural light
-Using airtight UL-approved fixtures for recessed ceiling lights with an un-insulated/unconditioned space above
When looking at outdoor lighting for energy efficiency, homeowners should consider:
-Security and utility lighting does not need to be bright to be effective
-Using fluorescent or LED, high-intensity discharge, or low-pressure sodium lights unless incandescent lights are automatically controlled to be on for
just a few minutes each day
-Using LED floodlights with combined photo sensors and motion sensors in the place of other security lighting options
-Using photo sensors with fluorescent or LED, high-intensity discharge, or low-pressure sodium lights
-Using outdoor light fixtures with reflectors, deflectors, or covers to make more efficient use of the light source and help reduce light pollution
-Using timers and other controls to turn decorative lighting on and off
-Using outdoor solar lighting
Terms and Definitions
Accent lighting - Draws attention to special features or enhances the aesthetic qualities of an indoor or outdoor environment.
Ambient lighting - Provides general illumination indoors for daily activities, and outdoors for safety and security.
Ballast -
A device used with an electric-discharge lamp to obtain the necessary circuit conditions (voltage, current and wave form) for starting and operating; all fluorescent and HID light sources require a ballast for proper operation. Dimming ballasts are special ballasts which when used together with a dimmer will vary the light output of a lamp.
Btu - British Thermal Unit, the amount of heat required to raise the temperature of one pound of
water by one degree Fahrenheit.
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. 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.
Direct lighting -
Lighting by luminaries distributing 90 to 100 percent of the emitted light in the general direction of the surface to be illuminated. The term usually refers to light emitted in a downward direction.
Directional lighting - Illumination on the work-plane or on an object predominantly from a single direction.
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).
Foot-candle - A measurement of the intensity of illumination. A foot-candle is the illumination produced by one lumen distributed over a 1-square-foot area. For most home and office work, 30-50 foot-candles of illumination is sufficient. For detailed work, 200 foot-candles of illumination or more allows more accuracy and less eyestrain. For simply finding one's way around at night, 2-10 foot-candles may be sufficient.
Indirect lighting -
Lighting by luminaries distributing 90 to 100 percent of the emitted light upward.
Lamp - bulb
Lamp life -
An average rating, in hours, indicating when 50% of a large group of lamps have failed, when operated at nominal lamp voltage and current; manufacturers use 3 hours per start for fluorescent lamps and 10 hours per start for HID lamps when performing lamp life testing procedures; every lamp type has a unique mortality curve that depicts its average rated life.
Lens - A glass or plastic element used in luminaries to change the direction and control the distribution of light rays.
Lumen - A measurement of light emitted by a lamp. As reference, a 100-watt incandescent lamp emits about 1750 lumens.
Reflector -
A device used to redirect the light by the process of reflection.
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.
Watt,W -
A unit of electrical power equal to 1 joule per second.
