Family: Technology
LED bulbs
Light comes from a semiconductor diode by electroluminescence, with no glowing filament.
Overview
LED bulbs create light through electroluminescence: an electrical current passes through a semiconductor diode, and electrons releasing energy emit photons directly, without heating a filament. A small driver circuit converts mains voltage to the low-voltage direct current the chip requires. Because emission comes from the material's electronic structure, the spectrum depends on the semiconductor and any phosphor coating used to produce white light. Public technical bodies describe this solid-state mechanism as fundamentally different from thermal sources. Actual behaviour varies with chip quality, driver design and heat management, so two LED products using the same basic principle can perform quite differently.
Production method
- How light is produced
Electroluminescence in a semiconductor diode; current through a chip emits light directly.
More detail
LED bulbs create light through electroluminescence: an electrical current passes through a semiconductor diode, and electrons releasing energy emit photons directly, without heating a filament. A small driver circuit converts mains voltage to the low-voltage direct current the chip requires. Because emission comes from the material's electronic structure, the spectrum depends on the semiconductor and any phosphor coating used to produce white light. Public technical bodies describe this solid-state mechanism as fundamentally different from thermal sources. Actual behaviour varies with chip quality, driver design and heat management, so two LED products using the same basic principle can perform quite differently.
Quality indicators
- Energy efficiency
Typically about 80-100+ lumens per watt; most energy becomes visible light.
More detail
LED lighting is generally described by energy agencies as among the most efficient widely available lighting, commonly delivering on the order of 80 to over 100 lumens per watt at the product level. Most of the input energy is converted to visible light rather than heat, though driver losses and thermal conditions reduce real-world figures. Reported efficacy varies considerably between products, brands and operating temperatures, and laboratory ratings may exceed everyday performance. Independent standards and testing programmes exist to verify claims. Efficiency also tends to improve across product generations, so newer models often deliver more lumens per watt than older ones under comparable conditions.
Qualitative characteristics
- Heat output
Lower radiated heat; waste heat is conducted from the chip and heatsink.
More detail
LED bulbs convert a larger share of energy to light and therefore radiate less heat forward than incandescent lamps, and they emit little infrared in the beam. However, they are not heat-free: the chip and driver generate waste heat that must be carried away by a heatsink or the housing, which is why many LED bulbs have metal or finned bases. Excessive junction temperature is a leading cause of reduced output and shortened life, so thermal design is central to performance. Enclosed fixtures can trap heat and affect rated bulbs. Overall surface and emitted heat are generally lower, but management remains an engineering concern.
Health-related indicators
- Light and the body
The same: what matters is the measured quantity, not the name of the technology
More detail
Exactly the same rule applies to LED light: the recommendations are expressed in melanopic equivalent daylight illuminance, not in the type of source. The spread between models in colour temperature and colour rendering is wide, so nothing about the effect on circadian rhythms can be concluded from the name of the technology — the characteristics of the particular lamp are needed.
Consumer experience
- Cost over time
Higher purchase price, lower running cost; payback depends on use and tariffs.
More detail
LED bulbs usually carry a higher purchase price than incandescent lamps, though prices have fallen substantially over time. Their running cost is lower because of higher efficiency and longer rated life, which reduces both electricity use and replacement frequency. Energy agencies present lifetime cost estimates suggesting savings in many typical households, but the actual payback depends on how many hours the bulb runs, local electricity tariffs, product quality and whether the rated life is achieved. Because these variables differ widely by region and usage, a single universal figure is not reliable, and published estimates should be treated as illustrative rather than guaranteed.
Regulatory notes
- Market access and efficiency rules
They took the place of the withdrawn category; efficiency requirements still apply
More detail
LED lamps took the place of a category withdrawn from the European market by regulation. The requirement itself did not go away: it applies to the efficiency of a light source rather than to its construction, and it covers the replacement products in the same way. The study tracing the incandescent phase-out describes exactly this transition.
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