LEDs rarely blow, they fade, and that changes how you buy them

The points below about lED lifespan are ordered by how much difference they make, not by how often they get repeated.

A different kind of failure

A filament breaks and the lamp stops, which makes replacement obvious and immediate for everyone in the household. A light-emitting diode loses output slowly, and manufacturers describe life as the point at which a stated proportion of the original output remains.

That means a lamp can be technically working while delivering noticeably less light than when it was installed. Because the decline is gradual, the eye adapts to it, and a room becomes dimmer over years without anyone deciding anything. Colour can drift as well, which is why one lamp in a row of identical fittings eventually looks slightly different from its neighbours.

Heat is what kills them

Diodes produce heat at the junction, and although they run cooler than filaments, the heat is concentrated in a very small area. The metal body of a lamp or fitting is a heat sink, and its job is to move that heat away from the diode. Enclosing a lamp in a sealed fitting traps that heat, which shortens the life of both the diode and the electronics driving it.

Room to room, insulation packed around a recessed downlight does the same thing, and it introduces a fire consideration as well as a lifespan one. Lamps rated for enclosed fittings exist precisely because the standard ones are not, and the distinction is often ignored.

The driver is usually what fails first

Every mains lamp contains a small power supply, and the capacitors in it are the least durable component in the assembly. Heat degrades those capacitors, which is why the same lamp lasts longer in an open fitting than in a closed one.

This is also why premature failures cluster: a batch of lamps in the same hot fitting fails within months of each other. Flicker, buzzing and reluctance to strike are usually driver symptoms rather than problems with the diodes themselves. A lamp that fails within a fraction of its stated life is normally a driver failure, and it is worth checking whether the fitting is the cause.

What the numbers on the box mean

Lumens describe output and are the number that should replace wattage in a buying decision, since efficiency varies between products. Colour temperature describes whether the light is warm or cool, and it is a description of appearance rather than of quality. The colour rendering figure indicates how faithfully colours appear under the lamp, and a low figure makes skin, food and fabric look wrong.

Live with it a while and stated lifespan figures are laboratory estimates under specified conditions, and real fittings are usually hotter than those conditions. Switching cycles matter too, because frequent switching stresses the driver, which is relevant in cupboards and hallways.

Integrated fittings and what you give up

Many modern fittings have the light source built in permanently, so when it fails the whole fitting is replaced rather than relamped. That allows better heat management and slimmer designs, and it means the fitting has a finite life measured in years rather than decades.

Over years, it also means a discontinued fitting cannot be matched, so one failure in a row of them forces replacing all of them. A replaceable lamp in a standard cap keeps the fitting serviceable indefinitely, which is the durable choice in a house you intend to keep. Where integrated fittings are used, buying a spare at the same time is the only practical hedge against discontinuation.

Taste is not the argument here; how a room performs is.

Getting a consistent room

Buying all the lamps for one room at the same time from the same range keeps colour consistent while they age together. Mixing colour temperatures within a single sightline is the most visible lighting error in a house and the easiest to avoid. Keeping a note of what is fitted where saves discovering the mismatch when one lamp is replaced years later.

When a room begins to feel dull for no obvious reason, replacing lamps that still work is a reasonable diagnosis. Disposal of these lamps is regulated as electrical waste in many countries, so they should not simply go in household rubbish.

Everything above, in order of what to do first

1. A different kind of failure. A filament breaks and the lamp stops, which makes replacement obvious and immediate for everyone in the household.
2. Heat is what kills them. Diodes produce heat at the junction, and although they run cooler than filaments, the heat is concentrated in a very small area.
3. The driver is usually what fails first. Every mains lamp contains a small power supply, and the capacitors in it are the least durable component in the assembly.
4. What the numbers on the box mean. Lumens describe output and are the number that should replace wattage in a buying decision, since efficiency varies between products.
5. Integrated fittings and what you give up. Many modern fittings have the light source built in permanently, so when it fails the whole fitting is replaced rather than relamped.
6. Getting a consistent room. Buying all the lamps for one room at the same time from the same range keeps colour consistent while they age together.

The takeaway

Buy a room at a time, keep fittings ventilated, and prefer a replaceable lamp over a sealed fitting you cannot service.

A room that is used will always beat a room that is finished.