LED first, because that is what you will be buying. Below it, the technologies it replaced — CFL, linear fluorescent, mains and low-voltage halogen and incandescent — with what has been withdrawn from UK sale, what is still obtainable, and what to replace each one with.
Cap codes describe how a lamp fixes into the holder; the technology below describes how it makes light. UK availability is set by the Ecodesign for Energy-Related Products regulations, which have progressively removed the least efficient lamp types from sale.
LED
Current standard — buy this
UK availability: Widely available
A semiconductor emitter driven by an electronic driver, either built into the lamp or remote in the luminaire. LED now covers every domestic cap type — B22, E27, E14, GU10, G9, G4, GX53, R7s and linear battens. It runs cool at the glass but hot at the driver, which is why enclosed and insulated installations need lamps specifically rated for them.
Efficacy
80-160 lm/W
Typical life
15,000-50,000 h typical
Check three things before buying: dimmable or not, colour temperature (2700 K warm, 3000 K neutral-warm, 4000 K cool), and whether the fitting is enclosed.
Compact fluorescent (CFL)
Being withdrawn
UK availability: Sale of most pin-based and non-directional CFLs ended under Ecodesign; stock is scarce
The 'energy saving' lamp of the 2000s — a folded fluorescent tube with an integral ballast. Slow to reach full output, poor at low temperatures, unhappy with frequent switching and generally not dimmable. Contains a small amount of mercury, so spent lamps must go to a WEEE collection point, not the household bin.
Efficacy
50-70 lm/W
Typical life
6,000-15,000 h
Replace with LED as they fail. Do not put CFLs in the general waste.
Linear fluorescent (T8 / T12 / 2D)
Withdrawn from sale
UK availability: T8 and T5 fluorescent tubes ended UK/EU sale from 2023; replacements are LED tubes or new LED battens
Still very common in garages, lofts, utility rooms and older kitchens. Retrofit LED tubes exist but the fitting usually has to be modified — the starter removed or replaced with a dummy, and magnetic ballasts bypassed. That is fixed wiring alteration inside a luminaire and is electrician's work.
Efficacy
60-100 lm/W
Typical life
10,000-20,000 h
Replacing the whole fitting with a sealed LED batten is normally cheaper and safer than retrofitting.
Mains halogen (GU10, B22, E27, linear R7s)
Largely obsolete
UK availability: Withdrawn from general UK sale from September 2021; some specialist and appliance types remain
An incandescent filament in a halogen gas fill. Excellent colour rendering and instant, perfectly smooth dimming — which is exactly why people miss it — but four to six times the running cost of LED and a genuinely hot surface. Halogen downlights are a common cause of scorched ceiling fittings and failed insulation clearances.
Efficacy
15-25 lm/W
Typical life
2,000-4,000 h
A 50 W halogen GU10 replaced with a 4-5 W LED GU10 gives similar output for around a tenth of the energy.
Low-voltage halogen (MR16 / G4 capsules)
Legacy
UK availability: Lamps still obtainable, but transformers are the problem
12 V lamps fed from a wire-wound or electronic transformer. Swapping to LED MR16 often fails because the old transformer has a minimum load of 20-60 VA that three or four LEDs never reach, producing flicker or non-starting. The reliable fix is to change the transformer for an LED driver, or convert the fittings to mains-voltage GU10.
Efficacy
15-20 lm/W
Typical life
2,000-4,000 h
Never handle a halogen capsule with bare fingers — skin oils create a hot spot and shatter the quartz.
Incandescent (GLS filament)
Obsolete
UK availability: Withdrawn from UK sale in stages from 2009-2012
The original tungsten filament lamp. Around 90% of the energy left as heat. Only decorative filament-look lamps remain, and those sold today are LED filament lamps that mimic the appearance. Genuine incandescent lamps still turn up in older properties, ovens and appliances.
Efficacy
10-15 lm/W
Typical life
1,000 h
If you still have filament lamps in daily use, changing them to LED is the fastest saving in the house.
Control
Dimming LED lighting
Dimming now has a page of its own — dimmable vs non-dimmable lamps, leading-edge and trailing-edge dimmers, 1-10 V and DALI control, the load trap, and the manufacturers that allow dimming from more than one switch position.
Mains-voltage halogen GU10s and non-directional halogen lamps were phased out of UK sale from 2021 under the Ecodesign Regulations, and remaining stock has largely gone. A few specialist types remain lawful to sell, including R7s linear lamps for some fittings, certain low-voltage capsules and oven, appliance and stage lamps. In practice the domestic replacement for almost every halogen lamp is now LED.
Do LED lamps really last 25,000 hours?
The LED chip may, but the electronics and the operating conditions usually decide. Heat is the enemy: enclosed fittings, insulated ceilings, poor-quality drivers and incompatible dimmers all shorten life dramatically. Buy lamps rated for enclosed luminaires where relevant, and treat repeated early failures in one fitting as a fitting or wiring fault rather than bad bulbs.
Converting a house to LED?
Changing halogen downlights, bypassing fluorescent ballasts, replacing transformers with LED drivers and specifying the right dimmer plates are all jobs worth getting right once. Paul covers Brighton, Hove and Sussex.