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National Lighting Product Information Program
Lighting Research Center - Rensselaer Polytechnic Institute

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Incandescent Lighting

Incandescent lighting is the most common type of lighting used in homes. It has traditionally delivered about 85% of household illumination.

Incandescent lamps operate without a ballast. They light up instantly, providing a warm light and excellent color rendition. You can also dim them. However, incandescent lamps have a low efficacy compared to other lighting options (10–17 lumens per watt) and a short average operating life (750–2500 hours).

Incandescent lamps are the least expensive to buy, but because of their relative inefficiency and short life spans, they usually are more expensive to operate.

Illustration of an incandescent lamp. The standard-shaped bulb, narrow at one end and wider at the other, has lead wires running vertically from the base into the lamp. The wires are connected by a narrow strip called a filament. Inside the bulb is nitrogen or argon gas.

The incandescent lamp is the oldest and most common type of lamp. Light is emitted when electricity flows through—and heats—a tungsten filament.

Types of Incandescent Lamps

These are the three most common types of incandescent lamps:

You can use the chart below to compare these types of lamps. If you don't already, it helps to understand basic lighting principles and terms before making comparisons.

Incandescent Lighting Type Efficacy
(lumens/watt)		 Lifetime
(hours)		 Color Rendition Index
(CRI)		 Color Temperature
(K)		 Indoors/Outdoors
Standard "A" bulb 10–17 750–2500 98–100 (excellent) 2700–2800 (warm) Indoors/outdoors
Tungsten halogen 12–22 2000–4000 98–100 (excellent) 2900–3200 (warm to neutral) Indoors/outdoors
Reflector 12–19 2000–3000 98–100 (excellent) 2800 (warm) Indoors/outdoors