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.