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Energy and Electric Lighting

In this section are assorted materials relating to energy and electric lighting. During the past three decades rising energy costs and environmental awareness have led the lighting profession to re-evaluate what they do. This has resulted in more energy-efficient equipment and designs.

Three terms are most important when thinking about the energy efficiency of electric lighting: lumens, watts and efficacy.

Lumens: The energy of the visible rays (light) given off per second is measured in lumens.

Watts: The energy of the electrical input per second is measured in watts.

Efficacy: The energy output divided by energy input is called efficacy and stated as lumens per watt (lpw). Efficacy is a measure of the efficiency of a lamp in producing visible light.

Energy Efficiency Over The Years
-- A comparison of light sources.

U.S. Lighting Energy
-- Who turns-on the lights.

Energy In Buildings
-- Lighting and other uses.

Energy In Buildings
-- Home and work.

To 19th
Century Hall
To 20th
Century Hall
Guest Lounge