Haitz’s Law: The Brightness and Cost of Illumination

Chapter 13 discusses Haitz’s law, which describes the exponential improvement in LED lighting performance and cost reduction. Lighting technology evolved from Edison’s carbon-filament incandescent bulb in 1879 to tungsten filaments in 1906, followed by fluorescent lamps introduced in 1939 and compact fluorescent bulbs in the 1980s. The invention of LEDs began in 1962 with red light, progressing to efficient blue LEDs in the 1990s, enabling bright white light through color mixing or phosphor conversion. Haitz’s law, formulated in 2000, states that the luminous flux per lighting package increases by a factor of 10 every 5–8 years (doubling every 2–3 years), while the cost per lumen decreases by a factor of 10 every 8–10 years. These trends have driven widespread adoption of LED lighting for homes and businesses. Future improvements may come from technologies like quantum-dot and perovskite LEDs, continuing the trajectory of efficiency and brightness gains.