LED lighting: the fit-and-forget saving

If any energy saving deserves the phrase fit and forget, it is LED lighting. The bulbs use a fraction of the electricity of the old incandescent and halogen ones, last for years, and the swap pays for itself quickly and then keeps paying with no further effort. This guide covers what you actually save, how to choose the right bulbs by lumens and colour, the handful of cautions worth knowing, and why there is no need to do it all at once.

What you actually save

An LED produces the same amount of light as an old incandescent or halogen bulb for a fraction of the electricity, often around a tenth to a fifth. The clearest case is the halogen spotlight, which is notorious for guzzling power. A 50W halogen downlight and its 5W LED equivalent give similar light, but one draws ten times the electricity.

Put that in money. A 50W halogen on for four hours a day uses about 73 kWh a year, roughly £19. The 5W LED doing the same job uses about 7 kWh, under £2. Across a kitchen of six or eight spotlights, replacing a roomful makes a visible dent, and the bulbs last so long that you rarely change one again.

Bulb type (similar light)	Power	Cost per year, 4h a day
Old incandescent	60W	~£23
Halogen spotlight	50W	~£19
Halogen (mains, standard)	42W	~£16
LED, standard bulb	9W	~£3.40
LED, spotlight	5W	~£1.90

At 26.11p per kWh electricity, Ofgem cap July to September 2026. Worked examples; your usage and bulb wattages will differ.

An LED bulb that costs a pound or two and saves £15 or more over its life pays for itself within months, then runs for years. The saving is modest against the heating bill, but it is one of the few changes you make once and never think about again. See where lighting sits in the wider picture in the electricity overview.

Choosing the right bulb: ignore watts, read lumens

With LEDs the old habit of buying by watts no longer works, because the whole point is that they use few watts. Buy by lumens instead, which measure actual brightness.

• Brightness. Roughly, 800 lumens replaces an old 60W bulb, 1,000 to 1,100 lumens an old 75W, and 400 to 500 lumens a dimmer 40W. The lumen figure is on every box.
• Colour temperature. This is a matter of taste, measured in kelvin. Warm white around 2,700K gives the cosy yellow light most people want in a living room or bedroom. Cool white around 4,000K to 5,000K is crisper and suits a kitchen, bathroom or workspace.
• Fitting. Check the cap matches your fixture: bayonet or screw for standard bulbs, GU10 or MR16 for spotlights. MR16 spots often run on a transformer that an LED may not like, so GU10 mains spots are the simpler swap.

If a light is on a dimmer, buy a bulb marked dimmable. A non-dimmable LED on a dimmer switch will flicker, buzz or refuse to dim properly. Even dimmable LEDs can be fussy with very old dimmer modules, which were designed for the high load of incandescent bulbs, so an LED-rated dimmer sometimes cures stubborn flicker.

One more figure on the box is worth a glance: the rated life, usually quoted in hours. A good LED is rated for 15,000 to 50,000 hours. At a few hours' use a day, even the lower figure is the better part of a decade, which is why you so rarely change one again once the house is converted.

The few cautions worth knowing

LEDs are easy, but a handful of points save you wasted money and the odd early failure.

• Avoid the very cheapest. Rock-bottom bulbs can be a false economy, dying early or giving poor, harsh light with a visible flicker. Middling quality is worth it for something meant to last years. Look for a sensible warranty and a recognised brand.
• Mind enclosed fittings. A sealed or recessed fitting traps heat, and heat is what shortens an LED's life. If the bulb sits in a fully enclosed glass shade or a tight downlight, buy one rated for enclosed use, or it may fail well before its quoted lifespan.
• Check the colour rendering. A CRI of 80 or above gives natural-looking colour. Cheaper low-CRI bulbs can make food and skin tones look slightly off, which matters in a kitchen or bathroom.

It is also worth knowing that an LED's quoted lifespan assumes reasonable conditions. Frequent switching on and off in a hallway or bathroom shortens the life of cheaper bulbs, and a bulb running on an unstable old transformer can flicker even when there is nothing wrong with the LED itself. None of these is a reason to hesitate. They are just the difference between a bulb that lasts a decade and one that quietly disappoints. If you want to check a bulb's real draw rather than trust the box, a plug-in energy monitor reads it at the socket.

Disposing of the old bulbs

What you do with the bulbs you remove depends on the type. Old incandescent and halogen bulbs are not recyclable in the usual sense and go in general waste, though they contain nothing hazardous.

Fluorescent tubes and the old curly low-energy CFL bulbs are different: they contain a small amount of mercury and must not go in the bin. Take them to a recycling centre or a shop that accepts them. Ordinary LED bulbs contain no mercury, though as electronic items they are best taken to a recycling point rather than binned where a household collection allows it.

Do it gradually, not all at once

There is no need to rip out every working bulb in one go. The saving comes from the bulbs that are on the most, so start there. Replace the kitchen and living-room bulbs first, since those burn the most hours, then swap the rest as they fail.

Working bulbs you barely use, in a spare room or a cupboard, can wait until they blow, because the electricity they save is tiny. Within a year of normal failures the house is mostly done, the lighting bill has shrunk, and you have effectively stopped buying bulbs, because an LED used a few hours a day can last a decade or more.

If you rent, lighting is one of the few energy improvements entirely within your control, since you can take the bulbs with you when you leave. See saving energy when renting for the other moves available to tenants, and quick wins under a tenner for cheap fixes to do alongside the bulb swap.